GS_EP_SAF_216_EN Rev 3

Exploration & Production

This document is the property of Total. It must not be stored, reproduced or disclosed to others without written authorisation from the Company.

GENERAL SPECIFICATION

SAFETY

GS EP SAF 216

Area classification

03 10/2008 Reviewed and rewritten in accordance with IP 15 3rd edition

02 10/2005 Addition of EP root to document identification and replaced reference API RP 500 by API RP 505

01 10/2003 Change of Group name and logo

00 04/2001 Old TotalFina SP SEC 216

Rev. Date Notes


General Specification Date: 10/2008

GS EP SAF 216 Rev: 03


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Contents

1. Scope .......................................................................................................................5 1.1 Purpose .............................................................................................................................5 1.2 Applicability........................................................................................................................5

2. Reference documents & interpretation .................................................................6

3. Terminology and definitions ..................................................................................9

4. Area classification procedure ..............................................................................13 4.1 Scenarios.........................................................................................................................13 4.2 Procedure ........................................................................................................................13 4.3 Deliverables .....................................................................................................................14

5. Partition between hazardous & non hazardous areas .......................................14

6. Hazardous zones...................................................................................................15 6.1 Sub division of hazardous areas into hazardous zones ..................................................15 6.2 Hazardous Zone ranking .................................................................................................15

7. Classification of open, sheltered and enclosed areas .......................................20 7.1 Open areas ......................................................................................................................20 7.2 Sheltered areas ...............................................................................................................20 7.3 Enclosed areas ................................................................................................................20

8. Determination of the hazard radius .....................................................................23 8.1 Characteristics of petroleum fluids...................................................................................23 8.2 Hazard radius ..................................................................................................................25 8.3 Typical sources of release ...............................................................................................25 8.4 Procedure for continuous & primary grade releases .......................................................26 8.5 Procedure for secondary grade releases.........................................................................26 8.6 Particular case of sheltered areas ...................................................................................26

9. Sizing and drawings of hazardous areas ............................................................27

10. Drilling rigs, equipment and well operations......................................................27

11. Internal combustion engines and fire heaters....................................................27





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11.1 Gas turbines ....................................................................................................................27 11.2 Gas and liquid fuel engines .............................................................................................29 11.3 Fired heaters....................................................................................................................30

12. Accumulator batteries in buildings .....................................................................30 12.1 Basics ..............................................................................................................................30 12.2 Location and hydrogen detection.....................................................................................30

13. Hydrocarbon storage............................................................................................31 13.1 Under-ground or within-embankment storage tanks........................................................31 13.2 Overhead, fixed roof storage tanks..................................................................................31 13.3 Overhead, floating roof storage tanks..............................................................................31 13.4 LPG storage tanks ...........................................................................................................31 13.5 Refrigerated LPG storage................................................................................................31 13.6 LNG storage ....................................................................................................................31

14. Miscellaneous........................................................................................................31 14.1 Laboratories.....................................................................................................................31 14.2 Analyser shelters .............................................................................................................32 14.3 Small storage of flammable products ..............................................................................33 14.4 Loading and filling operations (road tanker, rail car, drum filling) ....................................33 14.5 Jetties (loading, unloading)..............................................................................................33 14.6 Air intakes ........................................................................................................................33 14.7 Air exhausts .....................................................................................................................33 14.8 Chimneys and exhausts ..................................................................................................33 14.9 Flares...............................................................................................................................34 14.10 Traffic...............................................................................................................................34 14.11 Purging ............................................................................................................................34 14.12 Classification of enclosed buildings .................................................................................35

Annex 1 Table of hazardous equipment............................................................36

Annex 2 Area classification procedure .............................................................37

Annex 3 Procedure for assessing type & degree of ventilation......................38

Annex 4 Guidelines for the determination of the level of ventilation of sheltered areas...............................................................................39





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Appendix A - Determination of hazard radii values for equipment .........................40 A1. Equipment/arrangements generally generating continuous or primary grade releases ..40 A2. Equipment/arrangements generally generating secondary grade releases ....................45

Appendix B - Sizing of hazardous zones...................................................................48

Appendix C - Drilling rigs, equipment and well operations .....................................51 C1. Foreword..........................................................................................................................51 C2. Drilling, workover and pulling operations on Non Live Wells ...........................................51 C3. Surface mud systems ......................................................................................................52 C4. Rig gas vent.....................................................................................................................53 C5. Well servicing (Wire-line - Coiled tubing - Snubbing) operations on Live Wells ..............53 C6. Wellheads in production operation ..................................................................................53

Appendix D - Gas turbines..........................................................................................62

Appendix E - Gas/liquid fuel engines & heaters .......................................................66 E1. Gas engines.....................................................................................................................66 E2. Diesel engines .................................................................................................................66 E3. Fired heaters....................................................................................................................67

Appendix F - Hydrocarbon storage............................................................................69 F1. Overhead, fixed roof storage tanks..................................................................................69 F2. Overhead, floating roof tank (Category C on release) .....................................................70 F3. LPG storage stored under pressure ................................................................................70

Appendix G - Miscellaneous.......................................................................................72 G1. Laboratories.....................................................................................................................72 G2. Small storage of flammable products ..............................................................................72 G3. Air intakes ........................................................................................................................72 G4. Air exhausts .....................................................................................................................72 G5. Chimneys and exhausts ..................................................................................................72 G6. Traffic...............................................................................................................................72 G7. Enclosed buildings:..........................................................................................................73





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1. Scope

1.1 Purpose This specification defines the method called Area classification used to classify the locations where a flammable atmosphere may occur in such frequencies as to require special precautions for the construction and use of electrical apparatus or other potential ignition sources.

Area classification consists in:

• The partition of a facility into hazardous & non hazardous areas

• The sub-division of hazardous areas into hazardous zones

• The sizing of the hazardous zones.

1.2 Applicability This specification applies to:

• New or modified installations constructed by COMPANY or affiliates both onshore and offshore including LNG & LPG plants

• All E&P operations: drilling, production, treatment, storage and bulk distribution operations.

The scope is limited only to petroleum fluids and all other flammable products that are present in the installations.

This specification does not apply to:

• Toxic gases (which on manned installations may lead to more stringent rules)

• Combustible dusts

• Ignitable fibres

• Marine facilities covered by the IMO code (International Maritime Organisation) e.g. tankers.

Particular case of F(P)SO’s:

• This specification applies to the whole production deck facilities on FPSO’s (Floating, Production, Storage and Offloading) and to utilities on FSO’s (Floating, Storage and Offloading)

• For all spaces in the hull of a F(P)SO or concerning the cargo deck, GS EP STR 651 applies, which refers to IEC 60092-502





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• The battery limits between the process areas where GS EP SAF 216 applies and marine areas where GS EP STR 651 applies is defined hereafter:

WBP WBSCOTSCOTCCOTP

GS EP SAF 216

IGS EP STR 651 ZONE 0

ZONE 1

ZONE 2

PIPE AREA

Figure 1 - Battery limits on FP(S)O's

The case of tankers at berth that generate a hazardous area on unit limits is covered in Section 14.5 of this document.

This specification is not retroactive: its application to the facilities put in operation before the issue of this specification is not mandatory.

2. Reference documents & interpretation The reference documents listed below form an integral part of this General Specification. Unless otherwise stipulated, the applicable version of these documents, including relevant appendices and supplements, is the latest revision published at the EFFECTIVE DATE of the CONTRACT.

For the classification of hazardous areas in COMPANY petroleum installations, GS EP SAF 216 can be used as a stand-alone document unless a relevant National Regulation is applicable.

It complies with IEC 60079-10 “Classification of hazardous areas”.

Since IEC 60079-10 does not provide detailed recommendations regarding the extent of the hazardous areas in specific industries and applications and allows reference to other codes, GS EP SAF 216 is mainly based on IP 15.

The general philosophy of IP 15 and a lot of its detailed recommendations are adopted.

This specification and IP 15 differ mainly in areas not adequately covered by the code or where the code requires interpretation.

In some cases reference is made to standards other than IP 15, including API RP 505, although the latter shall not be used as a general reference.

The definitions of zones comply with the requirements of the ATEX Directive 1999/92/EC.

After the hazardous zones have been determined, the compatibility of all electrical equipment or any potential ignition sources with the zoning classification shall be ensured (see the relevant General Specifications of COMPANY by discipline for the design, installation and use of equipment with potential ignition source).





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Some of the specifications issued by the COMPANY disciplines (instrumentation, electricity, mechanics, HVAC, etc.) require ATEX-certified equipment (in conformity with ATEX Directive 94/09/EC).

Standards

Reference Title

EN 1834-1 Reciprocating internal combustion engines - Safety requirements for design and construction of engines for use in potentially explosive atmospheres - Part 1: group II engines for use in flammable gas and vapour atmospheres

EN ISO 13736 Petroleum products and other liquids - Determination of flash points - Abel closed cup method (Flash point range: -30°C/70°C)

EN ISO 2719 Determination of flash point - Pensky -Martens closed cup method (for flash points > 40°C)

IEC 61285 Industrial-process control - Safety of analyser houses

IEC 60079-4 Electrical apparatus for explosive gas atmospheres - Part 4: Method of test for ignition temperature

IEC 60079-10 Idem - Part 10: Classification of hazardous areas

IEC 60079-13 Idem - Part 13: Construction and use of rooms or buildings protected by pressurization

IEC 60079-16 Idem - Part 16: Artificial ventilation for the protection of analyzer(s) houses

IEC 60092-502 Electrical Installations in ships - Part 502: Tankers - Special Features

IEC 61285 Industrial - process control - safety of analyser houses

IEC 61892-6 Mobile and fixed offshore units - Electrical installations - Part 6: Installation

IEC 61892- 7 Mobile and fixed offshore units - Electrical installations - Part 7: Hazardous areas

NFPA 59A Standard for the production, storage and handling of liquefied natural gas

Professional Documents

Reference Title

API RP 505 Recommended practice for classification of locations for electrical installations at petroleum facilities classified as class I, Zone 0, Zone 1 and Zone 2

API STANDARD 521 Pressure-relieving and Depressurising Systems

API Publ 4615 Emission factors for oil & gas operations





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Reference Title IP 15 Area Classification Code for Petroleum Installations handling

flammable fluids - July 2005 (3rd edition)

API RP 2216 Ignition Risk of Hydrocarbon Liquids and Vapours by Hot surfaces in open air (3rd Edition 2003)

Regulations

Reference Title

ATEX Directive 1994/09/EC

Directive 1994/09/EC of the European Parliament and of the Council of 23 March 1994 on the approximation of the laws of the member states concerning equipment and protective systems intended for use in potentially explosive atmospheres

ATEX Directive 1999/92/EC

Directive 1999/92/EC of the European Parliament and of the Council of 16 December 1999 on minimum requirements for improving the safety and health protection of workers potentially at risk from explosive atmospheres

Arrêté du 9/11/72 Arrêté du 9 Novembre 1972 relatif à l’aménagement et l’exploitation de dépôts d’hydrocarbures liquéfiés (J.O. du 31 décembre 1972)

Codes

Reference Title

Not applicable

Other documents

Reference Title

Statement Of Requirements (SOR)

Safety Concept

Total General Specifications

Reference Title

GS EP CIV 402 Design & construction of oil field laboratory on production installations

GS EP HVA 100 Basis of design

GS EP ELE 001 Electrical design data





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Reference Title

GS EP ELE 021 Electrical design criteria for floating units

GS EP ELE 079 Electrical apparatus for explosive gas atmosphere

GS EP INS 101 Instrumentation engineering, supply and construction general requirements

GS EP MEC 290 Rotating machines packages

GS EP SAF 221 Safety rules for buildings

GS EP SAF 222 Safety rules for machinery and equipment handling hydrocarbon in enclosed areas

GS EP SAF 227 Safety rules for fired heaters

GS EP SAF 228 Liquid drainage

GS EP SAF 253 Impacted area, restricted area and fire zones

GS EP SAF 262 Pressure protection relief and hydrocarbon disposal systems

GS EP SAF 312 Guidelines for selecting and installation fire and gas detection system

GS EP STR 651 General principles for a F(P)SO design

3. Terminology and definitions There are three types of statements in this specification, the “shall”, “should” and “may” statements. They are to be understood as follows:

Shall Is to be understood as mandatory. Deviating from a “shall” statement requires derogation approved by the COMPANY

Should Is to be understood as strongly recommended to comply with the requirements of the specification. Alternatives shall provide a similar level of protection and this shall be documented

May Is used where alternatives are equally acceptable.

For the purpose of this specification, the following definitions shall apply (the terms defined in this section are often in bold characters in the text of the specification):

Area For the purpose of this specification, an area is a three-dimensional region or space (as per IEC 60079-10)

Adequate ventilation Natural, artificial, or a combination of both ventilations, sufficient enough to avoid persistence of flammable atmospheres within sheltered or enclosed areas but insufficient to avoid their initial formation and spread throughout the area. This will normally be achieved by a uniform ventilation rate of a minimum of twelve air changes per hour with no stagnant areas (IP 15)





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Air-lock Two self-closing vapour-tight doors with a space in between (the “gap”) kept above the pressure prevailing in the adjacent hazardous area. The minimum pressure difference between the gap and the hazardous area shall be 25 Pa (0.25 mbar). A local alarm buzzer plus an alarm sounding and lighting in the main control room are to be provided to warn the operators and personnel if both doors are open simultaneously. Loss of differential pressure in the gap between the two doors shall also alarm in the main control room

Area classification Area classification is the assessed division of a facility into hazardous areas and non-hazardous (or not classified or safe) areas, and the sub-division of hazardous areas into zones (refer to Section 5.3) (IP 15).

Competent Person who by combination of training, experience & supervision is able to make objective judgments

Dilution ventilation Artificial ventilation sufficient to maintain generally as non-hazardous an enclosed area containing a source of release or an aperture into a hazardous area (IP 15).

In the case of a turbine enclosure, this will normally be achieved by a uniform ventilation rate of a minimum of ninety air changes per hour with no stagnant areas (COMPANY definition from IP 15)

Emergency Shutdown (ESD)

Control actions undertaken to shutdown equipment or process in response to a hazardous situation (ISO)

Emergency Shutdown System

System, activated by automatic or manual signals, which undertakes the control actions to shutdown equipment or processes in response to a hazardous situation (ISO 10418)

Enclosed area Any building, room or enclosed space within which, in the absence or failure of artificial ventilation, the air movement will be limited and any flammable atmosphere will not be dispersed naturally (IP 15)

ESD system System of manual stations and automatic devices that, when activated, initiate a shutdown of the installation

Fire and Gas system (F&G)

The Safety System which monitors the temperature or the energy flux (fire), the concentration of flammable or toxic gases (gas), and initiates relevant actions (alarm, ESD, emergency depressurisation, active fire-fighting, electrical isolation) at pre-determined levels (COMPANY)





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Fired heater A vessel in which the temperature of a fluid is increased by the addition of heat supplied by a flame within the vessel (COMPANY from API). Fired heater is a generic term that covers all type of heaters including steam boilers, reboilers (flame tube or flue gas tube), indirect heaters (hot oil or hot water), incinerators, etc.

For the purpose of this specification, fired heaters are sorted out into the following classes:

• Class A: a heater that has heat utilisation equipment operating at approximately atmospheric pressure wherein there is a potential explosion or fire hazard that could be created by the presence of flammable volatile or combustible materials processed or heated in the heater

• Class B: a heater that has heat utilisation equipment operating at approximately atmospheric pressure wherein there are no flammable volatile or combustible materials being heated

Flammable atmosphere Mixture of flammable gases or vapours with air in such a proportion that, without any further admixture, it will burn when ignited. In the context of area classification the term “flammable” is preferable to “explosive” (IP 15)

Flammable limits (upper, lower)

The limits of combustibility of flammable gases or vapours when mixed with air (IP 15)

Flash-point Lowest temperature to which a liquid must be heated to give off sufficient vapour to form a flammable mixture with air. Ignition does not occur at the flash point unless there is a source of ignition (IP 15)

FPSO Floating, Production, Storage and Offloading system includes, in addition to storage and offloading capability, facilities for receiving crude oil from producing wells and processing it for export by separating water and gas (OGP)

FSO Floating, Storage and Offloading system consisting of a ship or barge-shaped floating hull incorporating tanks for storage of produced oil, and a method of loading the oil onto off take tankers (OGP)

Fuel source Same as ISO definition of "source of release" (API)

Hazard radius The hazard radius of a source of release is the largest horizontal extent of the hazardous area that is generated by the source when situated in an open area under unrestricted natural ventilation (IP 15)





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Hazardous area and zone

A hazardous area is defined as a three dimensional space in which a flammable atmosphere may be expected to be present at such frequencies as to require special precautions for the control of potential ignition sources (IP 15). All other areas are referred to as non-hazardous areas in this context. In a hazardous area three types of zones (0, 1 and 2) are recognised (IP 15)

HVAC Abbreviation for Heating, Ventilating and Air Conditioning

Ignition source Source of temperature and energy sufficient to initiate combustion (API)

Ignition temperature (synonymous with “auto”- and “self-ignition temperatures”)

The temperature at which a substance will begin to burn without application of any source of ignition (IP 15). The test conditions shall be as per IEC 60079-4

Interceptor/coalescer Vessel open or vented to atmosphere, used to separate petroleum liquids from other non-flammable liquids, typically water, and in which the petroleum liquids are present in smaller quantity. Typically they are found on the main oily water effluent treatment system of a facility (IP 15)

Laboratory A specific closed room or building where analyses are carried out by personnel

Normal operation Operation within the plant design parameters, including start-ups, shutdowns, routine maintenance and any degraded modes of operations foreseen during design

Open area An area that is outdoors without stagnant regions, where vapour is rapidly dispersed by wind and natural convection (IP 15)

Over pressurisation Artificial ventilation of an enclosed area to maintain the area at a controlled pressure above the ambient pressure (IP 15)

Over pressure obtained by artificial ventilation is referred to as simply over pressurisation in this specification

Safe area Other term used for non hazardous or not classified area

Self-closing doors Doors that are designed to close by themselves and to remain closed if not intentionally opened or kept opened

Sheltered/obstructed area

An area within or adjoining an open area (which may include a partially open building or structure) where, owing to obstruction, natural ventilation is restricted and less than in a true open area (IP 15)

Source of release Point from which a flammable gas, vapour or liquid may be released into the atmosphere (ISO)

Sump A vessel, open or vented to atmosphere, used to collect petroleum liquids, usually as a result of deliberate draining. Other liquids, e.g. water, can enter the sump but the petroleum liquid is normally an appreciable part of the total liquid entering (IP 15)





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Under pressurisation Artificial ventilation of an enclosed area to maintain the area at a controlled pressure below the ambient pressure (IP 15)

Under pressure obtained by artificial ventilation is referred to as simply under pressurisation in this specification

Units Areas within the installation resulting from its partition into a reasonable number of geographical and functional groups of equipment having the same type (e.g. hydrocarbon, pressure, inventory or ignition) and levels (high, medium, low) of risks (COMPANY)

Ventilation (natural, artificial)

Ventilation is a general term to indicate air movement and replacement by fresh air. Natural ventilation refers to ventilation caused by wind or convection effects. Artificial ventilation refers to ventilation caused by air purges or mechanical means (fans) (IP 15).

4. Area classification procedure The objective of the area classification is to reduce as much as possible the probability of coincidence of a flammable atmosphere and an ignition source.

The area classification shall be carried out before choosing appropriate electrical equipment or any equipment generating ignition sources.

The area classification process reduces the installation overall risk level through design improvements.

Additionally, the optimisation of the equipment layout shall be carried out to decrease the risk of ignition (e.g. pertinent grouping of equipment, optimisation of ventilation).

A flow diagram summarizing the basic steps of the procedure is included in Annex 2.

4.1 Scenarios The classification of hazardous areas takes into consideration events which are "liable to occur during normal or abnormal plant operating conditions” (IP 15).

Events not considered for Area Classification:

• Large gas/vapour releases from process vents or flares. Such releases shall require appropriate dispersion calculations

• Failure scenarios which are very unlikely to occur, such as the rupture of a process vessel or pipe (IEC 60079-10). For these scenarios reliance is placed on the Emergency Shutdown System and safety distances resulting from consequence analysis calculations (refer to GS EP SAF 253) to mitigate the consequence of a failure in the installation.

4.2 Procedure Area Classification shall be carried out by competent persons1. 1 For new projects it is recommended that Area Classification is conducted by a senior safety engineer assisted by

a process engineer. For the modifications of an existing installation the team should include a member of the operating crew. It should be noted that although the results of Area Classification have direct implications on the selection of the electrical apparatus, knowledge in electrical matters is not a must for conducting or participating to an Area Classification exercise.





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Area classification shall be conducted in 5 steps (IP 15):

• Partition of the installation into hazardous and non hazardous areas by identification of all the potential release sources of flammable products

• Sub-division of hazardous areas into hazardous zones which shall be ranked according to the estimated probability of the presence of a flammable atmosphere

• Determination of the hazard radii around each potential source of release

• Sizing of the hazardous Zone around each potential source of release

• Prepare/modify the hazardous area drawings; draw the envelopes of the zones.

4.3 Deliverables The following results shall be delivered:

• The table of hazardous equipment as per Annex 1

• When relevant, the calculation notes necessary for the hazard radius determination

• The drawings of hazardous zones showing the Zone envelopes & their main dimensions, the rest of the installation being classified as non hazardous or safe2.

5. Partition between hazardous & non hazardous areas The main principles governing the partition between hazardous and non hazardous areas are as follows:

• All hydrocarbons handled at a temperature above their flash point, or whose flash point is below 21°C (69.8 °F), are liable to generate hazardous areas

• A hazardous area is generated when a flammable mixture may be created further to an equipment release

• All equipment containing flammable products (for the definition & characterisation of a flammable product, see Section 8.1) shall be considered as potential release sources where the material quantities exceed the following thresholds:

Table 1 - Capacity thresholds above which hazardous area classification is required

Gas: volume corrected to 1

bar (a) pressure Liquefied

flammable gas Flammable liquid at

a temperature above its flash point

Inside 50 litres 5 litres 25 litres

Outside 1000 litres 100 litres 200 litres

• All-welded piping, flexible hoses (without fittings such as valves, instruments and flanges) and instrument tubing designed and constructed according to COMPANY specifications shall not generate hazardous areas.

2 As a requirement regarding the number of hazardous area drawings to be provided: for onshore plant, plan view and cross

sectional view; for offshore plant plan view of each deck level and at least two elevations.





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6. Hazardous zones The extent of the hazardous area depends on the rate of release, ventilation conditions, and fluid properties.

6.1 Sub division of hazardous areas into hazardous zones GS EP SAF 216 shall be used for:

• Defining the Zones 0 and 1 inside units (see Section 6.2.2)

• Defining the Zone 2 contour around the items of equipment located at the deck/unit surface limits.

The following documents shall be available for the determination of hazardous areas:

• Equipment list

• A layout drawing showing the position of all equipment, air inlets/exhausts and main sources of ignition (e.g. furnaces, roadways, flares, etc.)

• The extent of confinement (open, sheltered or enclosed) and HVAC calculations

• A process flow diagram

• A piping & instrumentation diagram

• Material identification & process conditions (e.g. temperature & pressure).

The main following information shall be collected in the table included in Annex 1:

• The equipment type & codification

• The nature of the hazardous fluid

• The main characteristics of the hazardous fluid.

6.2 Hazardous Zone ranking The determination of the following parameters shall be made in order to evaluate the rank of the hazardous zone:

• The grade of release as per Section 6.2.1

• The type of area (open, sheltered or enclosed) as per Sections 6.2.3 & 7

• The type of ventilation as per Section 6.2.4

All the above information shall be included in the table in Annex 1.

6.2.1 Grades of release (or types of source) Three grades of release3 are defined in terms of their likely frequency and duration.

6.2.1.1 Continuous grade release A release which is continuous or expected to occur for long periods: the cumulative duration of release exceeds 1000 hours per year.

3 For releases not considered for Area Classification see Section 4.1.





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Example: Gaseous atmosphere in a hydrocarbon storage tank.

6.2.1.2 Primary grade release A release which can be expected to occur periodically or occasionally during normal operation: the cumulative duration of release is in the range of 10 to 1000 hours per year.

Examples: Sampling connection (for regular, open to atmosphere sampling), operating purge, drain.

6.2.1.3 Secondary grade release A release which is not expected to occur in normal operation and, if it does, is likely to do so only infrequently and for short periods: the cumulative duration of release is less than 10 hours per year4.

Examples: Flanges, pump seals.

6.2.2 Zones Hazardous areas shall be identified and classified into Zones 0, 1 or 2 based on the frequency of the occurrence and duration of a flammable atmosphere.

The classification in zones or “zoning” is the partition of the installation into volumes in which a flammable atmosphere may be present (see Section 3).

The following definitions are from IP 15:

• Zone 0 That part of a hazardous area in which a flammable atmosphere is continuously present, or present for long periods.

• Zone 1 That part of a hazardous area in which a flammable atmosphere is likely to occur in normal operation.

• Zone 2 That part of a hazardous area in which a flammable atmosphere is not likely to occur in normal operation, and, if it occurs, will exist only for a short period.

For further guidelines refer to IP 15.

"Type of sources" and "zones" are not synonymous as the type of a Zone depends on the level of ventilation in the considered area and for enclosed areas, the pressure relative to the surrounding areas and their Zone classification.

4 Where releases are likely to be present for 1 to 10 hours per year but are anticipated in normal operation (e.g.

routine sampling points) they should be regarded as primary grade releases unless carried out under permit-to-work circumstances (IP 15).





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Throughout this specification, the zones are represented as follows:

Zone 0 Zone 1 Zone 2

6.2.3 Confinement (types of location) An area can be classified in three categories with respect to confinement:

• An open area (basically no roof/ceiling, no walls and floor made of grating) or

• A sheltered, partially enclosed, partially confined area (various combinations of solid floor, ceiling and walls or equivalent obstructions to natural draft) or

• An enclosed area.

The extent of confinement governs the determination of the level of ventilation.

The level of ventilation achievable for the three categories is described below (Section 6.2.4).

6.2.4 Ventilation The openness of an area is an important factor in determining the effectiveness of ventilation and the extent and severity of a hazardous area.

• Two boundary cases (open area, enclosed area) and an intermediate case (sheltered or obstructed area) are defined in Section 6.2.4.3

• The degree of ventilation (unrestricted, restricted, adequate or inadequate) is a key factor in determining the Zone classification of an area

• The level and extent of hazardous area classification depends on the ventilation of the zones where flammable vapours are likely to be present and to accumulate

• Conditions of ventilation and likelihood of detecting the leak may change the Zone definition for each grade of release.

• This specification defines only the functional requirements for ventilation or pressurisation systems to effectively dilute flammable gases or prevent the ingress of flammable gases in areas not suitable for the presence of a flammable atmosphere

• It is not a specification for the design and operation of ventilation and pressurisation systems. It does not cover in particular HVAC requirements for human comfort; temperature control and the extraction of smoke during/after a fire (refer to GS EP SAF 221 for ventilation in buildings and to GS EP HVA 100 for basis of HVAC design)

• Ventilation can either be natural when it is caused by wind or convection effects or artificial when it has to be provided to dilute and remove flammable gases or vapour released within a room or a building

• Pressure differential with respect to surrounding areas can only be achieved for enclosed areas and in conjunction with artificial ventilation





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• For all artificial ventilation systems, the ventilation air shall be taken from a non-hazardous area and shall not, by virtue of any chemical products or impurities which it may contain produce harmful effects or introduce a reduction of the safety level.

6.2.4.1 Types of ventilation The different types of ventilation are as follows:

6.2.4.1.1 Adequate/Inadequate ventilation Adequate ventilation is defined as ventilation sufficient enough to prevent the accumulation of concentrations of flammable gas-air. This will normally be achieved by a uniform ventilation rate of at least 12 volumetric air changes per hour with no stagnant areas.

Open areas are considered as adequately ventilated and typically, air velocities will frequently be above 2 m/s and rarely less than 0.5 m/s.

By definition, any ventilation that does not match the above criteria will be considered as inadequate which normally results from natural draft less than 0.5 m/s or artificial ventilation rate less than 12 volumetric air changes per hour (sheltered areas or loss of ventilation of an enclosed area for example).

6.2.4.1.2 Dilution ventilation Dilution ventilation shall be sufficient to immediately bring the flammable gas concentration below 20% of the Lower Flammability Limit (LFL) and keep it so all the time.

Typical ventilation rates covering all scenarios for dilution ventilation cannot be proposed. A calculation shall be carried-out to estimate hydrocarbon leaks5. This can only be achieved by a very large number of air changes (well in excess of 12 per hour).

It shall be based on the largest secondary grade release.

Should simultaneous releases from more than one secondary grade releases be likely, then the cumulated release shall be considered.

Ventilation rates higher than those required for dilution ventilation may be required in case ventilation also serves other purpose than dilution to prevent flammability (e.g. in case toxic fluids are involved or in case high cooling requirements).

6.2.4.2 Loss of artificial ventilation in enclosed areas Loss of artificial ventilation can cause the level of ventilation of the area to be less than dilution ventilation or even less than adequate. In such event:

• The Zone classification is temporarily down graded

• All potential sources of ignition incompatible with the downgraded zoning shall be isolated (electrically or else, with or without delay).

5 Methods to calculate minimum introduction rates to achieve adequate ventilation are proposed in API RP 505

(Appendices B, first edition 11/1997, reaffirmed 11/2002). Unless otherwise specified, the default values for gas leaking rates should be those of API Publ 4615, assuming the equipment is in poor condition (leaking rates) but there is no failure (e.g. pipe rupture).





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6.2.4.3 Ventilation assessment A method included in Annex 3 of this specification will help to assess the type & level of ventilation for each type of area (open, sheltered or enclosed).

The level of ventilation available in a location shall be established in order to allow Zone classification:

• Open areas shall be deemed adequately ventilated (natural draft exceeding 2 m/s)

• For sheltered areas (or obstructed areas), the level of ventilation shall be established on the basis of API 505 (see Annex 4)

• For enclosed areas, ventilation is inadequate; it can be made adequate or better (e.g. dilution) by providing artificial ventilation to disperse any flammable atmosphere

6.2.4.4 Pressurisation Pressurisation shall be provided to ensure the protection of a room or building6:

• Containing electrical equipment or other potential sources of ignition and located in a hazardous area where flammable gases or vapours may enter (over pressurisation)

• Containing sources of release and surrounding by a safe area containing electrical equipment or other potential sources of ignition (under pressurisation)

The ingress of gases or vapours into a room is prevented by maintaining inside it a protective gas at a higher pressure than that of the outside atmosphere.

The egress of gases or vapours from a room is prevented by maintaining inside it a protective gas at lower pressure than that of the outside atmosphere.

This section does not deal with the electrical apparatus for which protection by pressurisation in hazardous areas follows the electrical codes (the protection of the electrical apparatus in hazardous areas shall comply with COMPANY specification GS EP ELE 079).

The protection by pressurisation of rooms and buildings containing electrical equipment shall comply with IEC 60079-13 and with this specification (some of the requirements of this section exceed the requirements of IEC 60079-13).

The types of pressurisation and associated construction requirements for buildings are addressed in IEC 60079-13.

The pressurizing gas shall not, by virtue of any chemical products or impurities which it may contain, produce harmful effects or introduce a reduction of the safety level.

6.2.4.4.1 Over pressurisation protection Protection by over pressurisation is achieved when artificial ventilation or static pressurisation controls the pressure inside an enclosed area sufficiently above that of the surrounding hazardous area to prevent ingress of a flammable atmosphere from an outside fuel source.

The difference in pressure to be maintained shall be greater or equal to 25 Pa (0.25 mbar). Overpressure should be monitored or detected by a pressure switch as a minimum.

Loss of overpressure shall initiate an alarm.

6 A room or building is an enclosure of sufficient size to permit the entry of a person.





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Pressurised enclosed areas shall be provided with fixed gas detection as per GS EP SAF 312 to immediately and automatically isolate all ignition sources not suitable for Zone 17.

6.2.4.4.2 Under pressurisation protection Protection by under pressurisation is achieved when artificial ventilation keeps the pressure inside an enclosed area sufficiently below that of the surrounding area to prevent possible egress of a flammable atmosphere to an outside less or non hazardous area.

The difference in pressure to be maintained shall be greater or equal to 25 Pa (0.25 mbar). Under pressure should be monitored or detected by a pressure switch as a minimum.

Loss of under pressure shall initiate an immediate alarm, and isolate all ignition sources located in the vicinity of the enclosed area and not suitable for Zone 1.

Isolation of these ignition sources on loss of under pressure may be delayed to allow the loss to be investigated.

7. Classification of open, sheltered and enclosed areas

7.1 Open areas Where a facility is categorized as an open area (provided with adequate natural ventilation), the following classification applies:

• Zone 0 is generated by a continuous grade release

• Zone 1 is generated by a primary grade release

• Zone 2 is generated by a secondary grade release.

7.2 Sheltered areas For a sheltered or obstructed area, the natural ventilation may be restricted. The level of ventilation may then be adequate or inadequate (see definitions in Section 6.2.4).

When the level of ventilation of a sheltered/obstructed area is assessed as adequate, the classification rules for open areas shall apply (see Section 7.1).

When the level of ventilation of a sheltered/obstructed area is assessed as inadequate, the area shall be classified as an enclosed area (see table in Section 7.3 - “inadequate” column).

7.3 Enclosed areas An enclosed area is any building, room or enclosed space within which, in the absence or breakdown of artificial ventilation, the ventilation will be regarded as inadequate (refer to Section 6.2.4).

The Zone classification of the outside areas shall be taken into account when classifying the enclosed areas in contact (via an aperture) with them unless the enclosed walls, ceilings, floors and any ducting are vapour-tight by construction.

7 If gas detection is not provided or if a source of primary grade of release is installed in the building (each of them

requiring derogation to this specification approved by COMPANY), loss of overpressure shall automatically and immediately isolate all ignition sources not suitable for Zone 1.





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A vapour-tight door or hatch, locked in normal operation and opened only under a permit to work procedure, and air-locks should not be considered as apertures. One ordinary door or one door of a vapour-tight design (self-closing or not) shall be considered as an aperture.

The outside areas in contact through an aperture with the enclosed area shall be considered for classification.

Areas having a direct opening onto another area:

• Shall take the Zone classification of adjacent areas if they are more stringent

• Shall extend their own classification to adjacent areas of openings if they would otherwise be less stringent.





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Zone classification of enclosed areas Type of ventilation Grade of

internal release

Internal ignition sources Inadequate Adequate Dilution (2) Dilution +

overpressure Dilution + under

pressure Overpressure (4) Under pressure (4)

Continuous (1) (3) yes Not allowed Not allowed Not allowed Not allowed Not allowed Not allowed Not allowed Continuous (1) (3) no Not allowed Not allowed Not allowed Not allowed Not allowed Not allowed Not allowed Primary (1) (3) yes Not allowed Not allowed Not allowed Not allowed Not allowed Not allowed Not allowed Primary (1) (3) no Not allowed Not allowed Not allowed Not allowed Not allowed Not allowed Not allowed Secondary (3) yes Zone 1 if

surrounded by a safe zone

Zone 2 Not classified if surrounded by a safe zone

Not classified if surrounded by a Zone 0, 1 or 2.

Not classified if surrounded by a safe Zone containing an ignition source

Zone 1 or 2 depending on the ventilation rate, if surrounded by a safe zone


Secondary (3) no Zone 1 if surrounded by a safe Zone or a Zone 1 or 2.

Zone 2 Not classified if surrounded by a safe zone

Not classified if surrounded by a Zone 0, 1 or 2.

Not classified if surrounded by a safe Zone containing an ignition source



No source yes Zone 0 if surrounded by a Zone 0 or 1 Zone 1 if surrounded by a Zone 2

Zone 0 if surrounded by a Zone 0 Zone 1 if surrounded by a Zone 1 Zone 2 if surrounded by a Zone 2

Not classified if surrounded by a safe zone

Not classified Not classified if surrounded by a safe zone

Not classified Not classified if surrounded by a safe zone

No source no Zone 0 if surrounded by a Zone 0 or 1 Zone 1 if surrounded by a Zone 2

Zone 0 if surrounded by a Zone 0 Zone 1 if surrounded by a Zone 1 Zone 2 if surrounded by a Zone 2

Not classified Not classified Not classified Not classified Not classified

(1) With the exception of accumulator batteries (see Section 12.1), continuous or primary grade sources shall not be located within an enclosed area. Such design shall require formal derogation to this specification.

(2) An area within a larger enclosure subject to local artificial ventilation, i.e. by extractor fan, shall be classified according to the local ventilation rate in that local area, i.e. either dilution or adequate ventilation depending on which is met.

(3) With a source of small hazard radius, e.g. a sample point, the local ventilation may be high enough to prevent the source from influencing the classification of the whole enclosure. There should still be a local Zone 1 or 2 around the source and the extent of this Zone should be greater than in the open air, typically about twice the extent.

(4) Typical case of living quarters where ventilation rate is low. General Note: In the above table, ‘If’ to be taken as a restrictive condition





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8. Determination of the hazard radius This section provides the general requirements for the determination of the hazard radius.

Hazard radii may be determined by either:

• Direct examples limited to common facilities given in Sections 10, 11, 12, 13 and 14, or

• A point source method developed in present Section 8, or

• A risk based method for secondary grade release equipment or when the release rate (hole size & pressure) is unknown (IP 15).

Hazard radii depend on the following parameters:

• The grade of release (determined in Section 6.2.1)

• The fluid category (determined as per Section 8.1)

• The release pressure

• The hole release size

For the determination of hazard radii, see Appendix A.

8.1 Characteristics of petroleum fluids For Area Classification in petroleum installations, the classification of petroleum fluids shall be done in two steps, first in classes then in categories:

• The Class of liquid hydrocarbons relates to their flash point and handling temperature at actual storage or process conditions

• The Category is derived from the class and indicates to which extent a fluid on release can form a flammable mixture with air. This is a determining factor in the calculation of the hazard radius (see Section 8 & Appendices A & B).

8.1.1 Classification of petroleum fluids based on closed cup flash points (IP 15)

Class 0 I II III

Fluid LPG Liquid hydrocarbon with TF < 21°C

Liquid Hydrocarbon with 21°C≤TF<55°C

II(1): TH < TF

II(2): TH≥ TF

Liquid Hydrocarbon with 55°C≤TF<100°C

III(1): TH < TF

III(2): TH≥ TF

Where: TF is the flash point of the fluid in °C.

TH is the temperature at which the fluid is handled in °C.

Unclassified are liquid hydrocarbons with a flash point above 100°C. However, they should be considered as class III (2) when handled at, or above, their flash point temperature8.

8 For further guidance on petroleum fluids classification refer to IP 15, Annex A.





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8.1.2 Fluid Categories Following are guidelines for application of Categories to the oil and gas production installations9.

• Unstabilised crude oil should be put in Category B because of the wide boiling temperature range involved

• Stabilised crude oil should be put in Category C. Crude oil may be regarded as stabilised when separation from gas has been at a pressure at or below 1.1 bar(a).

Category Definition

G(ii) Refinery hydrogen

G(i) A typical methane-rich natural gas.

A Any flammable liquid that, on release, would vaporise rapidly or substantially. Includes LPG and lighter flammable liquids e.g. LNG. Also includes any flammable liquid at a temperature sufficient to produce, on release, more than 40% vol vaporisation with no heat input other than from the surroundings.

B Any flammable liquid, not in Category A, but at a temperature sufficient for boiling to occur on release.

C Any flammable liquid, not in Category A or B, but which can be at a temperature above its flash point or form a flammable mist or spray.

8.1.3 Relationship between fluid classification & fluid category The following table may be used to convert classification to fluid category:

Classification of petroleum based on closed cup flash points Fluid category

Class Description Handled above flash point

Handled above boiling point

Can be released as mist

Handled below boiling point and

cannot be released as mist

0 LPG Yes A A A(2)

I Flash point less than 21°C Yes B C C

II (1)

II (2)

Flash point 21-55°C


No

Yes

N/A(1)

B

C

C

N/A(1)

C

III (1)

III (2)



No

Yes

N/A(1)

B

C

C

N/A(1)

C

Unclassified (1)

Unclassified (2)

Flash point > 100°C

Flash point > 100°C

No

Yes

N/A(1)

B

C

C

N/A(1)

C

(1) Not applicable because liquids not handled above their flash point cannot be above their boiling point.

(2) Cryogenic fluids need special consideration.

9 For further guidance on petroleum fluids classification refer to IP 15, Annex A.





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8.2 Hazard radius The hazard radius of a source of release is the largest horizontal & vertical extents of the hazardous area that is generated by the source when situated in an open area under unrestricted natural ventilation.

The hazard radius is not the result of a fully deterministic approach. It should be regarded as a standard to be used when no better method is available. It is not a substitute for good engineering judgement. For example one may consider that a particular item of equipment gives rise to a critical risk and decide to enlarge the associated hazardous area.

The hazard radius does not take into consideration all the actual physical properties of the gas, characteristics of the environment and conditions of release. Gas dispersion calculations, if necessary, shall be carried out as per GS EP SAF 253, using codes (computer programs) approved by COMPANY.

8.3 Typical sources of release The typical grades and sources of release for the current standard equipment/arrangements are included in the following table:

Type of equipment Sources of release Typical release Grade

Pumps (1) Seals, vents, drains, valves, piping flanges, filter/strainers

Secondary

Drains & sample points Drain sampling point Primary or secondary (depends on the frequency of sampling)

Compressors Seals & joints Secondary

Process vents (includes degassing & cold vents)

Discharge point assuming that all welded collecting piping = safe area

Continuous, primary or secondary (depends on the frequency of venting)

Instrument vents Discharge point Continuous, primary or secondary (depends on the frequency of venting)

All welded piping None Safe area

Flanges & valves (2) Seals & joints Secondary

Pig receivers Door Primary

Sumps Ventilated concrete slab/metal grill

Continuous or Primary

Interceptors or coalescers Ventilated concrete slab/metal grill

Primary

(1) In case of frequent seal failure in “normal operation”, should be considered as primary source of release

(2) In case of frequent failure in “normal operation”, should be considered as primary source of release.





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8.4 Procedure for continuous & primary grade releases The hazard radii may be determined using the generic hazard radius values included in the tables in Appendix A1; however, a more accurate value of hazard radius may be determined using dispersion models when data for the equipment are available.

8.5 Procedure for secondary grade releases The hazard radii may be determined using the generic hazard radius values included in the tables in Appendix A2; however, a more accurate value of hazard radius may be determined using dispersion models when data for the equipment are available.

8.6 Particular case of sheltered areas There are many cases of natural ventilated situations where there is some restriction to free air circulation:

• Some associated with an otherwise open area layout but where there is an obstruction in the form of a wall, adjacent structure or open-sided roof

• Others where a partial restriction to natural air flow is in-built by design in the form of a structure that has pierced openings or louvers to provide weather protection.

Note 1: R1 is the hazard radius obtained from Section 8.

Note 2: The wall should extend to at least the full vertical height of the hazardous area if it is to be used as a deflection wall.

Note 3: S is the shortest distance from the source to the edge of the retaining wall.

Figure 2 - Extent of hazardous area around wall producing sheltered area (gas or vapour lighter or heavier than air)





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9. Sizing and drawings of hazardous areas The extent of hazardous areas shall be conducted in two steps:

• First the hazard radius around each potential release source is determined as per Section 8

• Then this hazard radius is used to set up the three dimensional envelope of the hazardous area taking account of the type of zone, the ventilation in the area, the natural or artificial obstacles in the gas path, and the buoyancy of the release.

Hazardous zones sizing is detailed in Appendix B.

To draw the line between hazardous areas and non hazardous areas, the following rules apply:

• For skid mounted equipment (e.g. packages), it shall be assumed that secondary grade release sources (see Section 6.2.1) can be anywhere at the periphery of the equipment skid. A detailed study of each single secondary grade release is not required. It is only in case of difficulty that the exact location of the sources of release shall be considered. This would require input from the equipment VENDOR

• For non skid mounted equipment e.g. vessels, it shall be assumed that sources of secondary grade release are located at a distance of 0.8 m from the equipment external limits (e.g. vessel shell)

• The accurate location of each primary or continuous grade releases shall be considered for drawing the hazardous areas they generate

• Two adjacent hazardous areas shall be merged in any point where their distance does not exceed 3 m

• Generally a whole offshore deck or a whole onshore unit containing essentially hydrocarbon processing or storage equipment should be classified as Zone 2 after identifying the Zones 0 & 1 if any

• Extension of Zone contours at unit borders should be considered on a case by case basis.

10. Drilling rigs, equipment and well operations See Appendix C for the classification of drilling rigs, equipment and well operations.

11. Internal combustion engines and fire heaters Reference is also made to GS EP SAF 222, GS EP SAF 227 and GS EP MEC 290.

11.1 Gas turbines

11.1.1 Main principles for classification Gas turbines are potential sources of ignition and release.

Gas turbines shall not be installed in Zone 0 or Zone 1. As a consequence, gas turbines shall drive equipment that is either a source of secondary grade release (hydrocarbon gas compressor, oil pump) or not a source of release (alternator, water pump).

Gas turbines shall be installed in an enclosed area (called turbine enclosure) in order to reduce the noise level and make the area safe by dilution ventilation.





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It may happen that the turbine enclosure, the driven equipment and all the auxiliaries are enclosed in a bigger enclosure (called unit room).

The main justification of a unit room is to provide a safe environment to the driven equipment (e.g. generator, compressor or pump) if it has to be installed in a hazardous area (e.g. offshore).

In cases where the driven equipment does not require a safe environment or is installed in a safe area of the plant (e.g. onshore), the unit room is not mandatory.

For the classification of gas turbines, see Appendix D.

11.1.2 Turbine enclosure principles The turbine enclosure shall be provided with a ventilation system for cooling and dilution purposes.

The turbine enclosure ventilation system shall be independent from the ventilation system of the unit room, if any.

Turbine enclosure ventilation is ensured by a “main” ventilation system backed up by a “stand by” ventilation system.

The stand by ventilation shall automatically start on loss of main ventilation.

Stand-by ventilation shall be supplied by an emergency power source independent from normal power and shall be suitable for Zone 1.

After the turbine is shutdown, the auxiliary power source shall be capable of keeping the ventilation running until hot surfaces have been cooled down below the auto-ignition temperature of the gas/air mixtures that may be present in the enclosure.

Differential pressure shall be provided as applicable:

• Under pressure where the turbine enclosure is surrounded by a safe area

• Overpressure where the turbine enclosure is surrounded by a hazardous area.

In both cases (under pressure and overpressure), an alarm shall be initiated in the control room if the differential pressure drops below 25 Pa (0.25 mbar). The electrical equipment within the enclosure shall be certified for use in Zone 2 as a minimum.

The turbine enclosure shall be ventilated before energizing of any electrical equipment not suitable for Zone 1. The purge ventilation shall be suitable for operation in Zone 1 and shall ensure a minimum of 5 air changes.

11.1.3 Unit room principles Any electrical equipment outside the turbine enclosure (power generator or auxiliaries) shall be suitable for use in the type of hazardous area that prevails, either Zone 2 or safe area.

Where provided, the unit room of the totally enclosed type, shall be rendered safe as follows:

• A unit room containing a secondary fuel source and surrounded by an external hazardous area shall be adequately ventilated

• A unit room containing a secondary fuel source and surrounded by an external safe area shall be adequately ventilated and under-pressurised at a minimum of 25 Pa





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• A unit room containing no fuel source and surrounded by an outside Zone 2 hazardous area shall be maintained at a minimum overpressure of 25 Pa with respect to all surrounding classified areas with potential openings to the room including the turbine enclosure itself

• In both cases, an alarm shall be provided in the control room if the differential pressure drops below 25 Pa.

See Figures D1 to D3 in Appendix D.

11.1.4 Hot surfaces in areas not provided with dilution ventilation (e.g. exhaust pipes) When located in hazardous area, hot surfaces shall be thermally insulated. Their surface temperature shall not exceed 80% of the ignition temperature (in °C) of any flammable gas mixtures likely to be present. By default the surface temperature shall not exceed 200°C (corresponding to ATEX requirement for T3 skin temperature). For more details refer to API 2216.

11.2 Gas and liquid fuel engines Spark ignited gasoline-fuelled engines shall not be installed in hydrocarbon plants.

A diesel fuel engine and its fuel circuit are not considered as a source of release, i.e. they do not generate a hazardous area10. The quantity of hydrocarbon vapour involved is small enough to be disregarded. A diesel fuel engine is a source of ignition, mainly due to its high skin temperature and the possibility of spark emission.

Gas engines, as gas turbines, are sources of ignition and release.

Diesel and gas engines:

• Shall not be installed in Zones 0 or 1

• Shall not be installed in a Zone 2 where a category G(ii) gas (e.g. Hydrogen, acetylene) may be present

• Shall not be installed in areas where liquid hydrocarbon spillage or liquid mist may occur and result in the release of vapours with an auto-ignition temperature lower than 135°C

• Should not be installed in a hazardous area.

Diesel and gas engines, their auxiliaries and driven equipment, shall in any case be adequately ventilated even if driving equipment that does not constitute a fuel source.

Offshore Diesel and gas engines installed in Zone 2 shall conform to EN 1834-1 or be installed in an enclosure, protected by internal overpressure which complies with the requirements of Section 6.2.4.

The above requirement11 is not mandatory for onshore gas engine or Diesel engine if their driven equipment and their “auxiliaries” are installed at a distance specified in Appendices E1 & E2.

For the classification of gas and liquid fuel engines, see Appendices E1 & E2.

10 When fed with crude oil, such an engine shall be considered as a source of release. 11 Conformity to EN 1834-1 or installation in an enclosure, protected by internal overpressure complying with the requirements of

Section 6.2.4.





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11.3 Fired heaters Fired heaters themselves do not generate hazardous area.

Main burners, igniters and pilots do not generate hazardous area.

As a consequence of what precedes, air intakes for natural draught fired heaters can be located in the immediate vicinity of the burner, as long as they are outside the Zone 2 hazardous area generated by the fuel or the process lines.

For the classification of fired heaters, see Appendix E3.

12. Accumulator batteries in buildings

12.1 Basics With the exception of small capacity sealed batteries which are outside the scope of this specification, accumulator batteries are regarded as primary sources of release: they release hydrogen when they are being charged.

The purpose of ventilating a battery location or enclosure is to maintain the hydrogen concentration below the 4% volume hydrogen Lower Flammability Limit (LFL) threshold. Battery locations and enclosures are to be considered as safe from explosions when, by natural or forced (artificial) ventilation, the concentration of hydrogen is kept below the LFL limit.

Particular attention shall be given to the fact that the gas emitted is lighter than air and will tend to accumulate in any pockets at the top of the space. When batteries are arranged in two or more tiers, all shelves shall have not less than 50 m space, front and back, for circulation of air. Reference is made to international standard IEC 61892-6 and IEC 61892-7 for the installation of accumulator batteries in enclosures/buildings. This Section 12 sets out the basic safety requirements for the design of installations designed by or on behalf of COMPANY.

Two types of accumulator batteries shall be considered:

• Open batteries which include recombination type or vented batteries

• Sealed batteries.

Refer to GS EP ELE 001 for the classification of accumulator batteries, and GS EP ELE 021 for the electrical design of floating units. Refer also to GS EP HVA 100 for the dilution ventilation criteria for accumulators.

When dilution ventilation is achieved by artificial means, the battery charge shall be stopped on loss of ventilation.

12.2 Location and hydrogen detection Accumulator batteries and their charger may be located in the same cubicle only if this cubicle is provided with natural or artificial dilution ventilation as per the requirements of this Section.

The requirements set out in Section 12.1 shall apply to all batteries liable to release flammable gases. This section addresses additional requirements that depend on the capacity and discharge voltage of the accumulator batteries.

• Sealed batteries: can be located in the same room as electrical equipment and no hydrogen detection is required





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• Open batteries shall be located in a dedicated battery room. The safety of personnel handling the acid fluids associated with open batteries in this room shall be considered: provision of an eye wash station. The fans in this battery room shall be suitable for operation in Zone 1 for category G(ii) gases. Hydrogen detection shall be installed. On hydrogen detection the battery charge shall be switched off (in order to stop hydrogen release) and all ignition sources in the room shall be isolated, with the exception of the electrical equipment certified for Zone 1 category G(ii) gases.

13. Hydrocarbon storage For storage containing Category C or non-hazardous fluids on release, IP 15, Section 3 shall be complied with. This is illustrated in Sections 13.1, 13.2 and 13.3. As part of this specification, IP 15 recommendations shall apply even if the ambient temperature exceeds 30°C.

13.1 Under-ground or within-embankment storage tanks For under-ground or within-embankment storage tanks containing liquids of Class I, II (2) or III (2), the extent and classification of hazardous areas around the surface vents depend on whether the tank is pump or gravity fed. Refer to IP 15, Section 3 for more details.

13.2 Overhead, fixed roof storage tanks For the classification of overhead, fixed roof storage tanks, see Appendix F1.

13.3 Overhead, floating roof storage tanks For the classification of overhead, floating roof storage tanks, see Appendix F2.

13.4 LPG storage tanks The extent and classification of hazardous areas around storage vessels containing Class 0 liquids (LPG) shall be based on French regulation, namely the "Arrêté du 9 ovembre 1972" for liquefied hydrocarbons stored under pressure at more than 0°C ambient temperature (Category A2 under French classification).

For the classification of LPG storage tanks, see Appendix F3.

13.5 Refrigerated LPG storage LPG stored at atmospheric pressure (below 0°C) is outside the scope of this specification. Refer to the local regulations and standards prevailing in the country of application.

13.6 LNG storage NFPA 59A or more stringent national regulations shall be followed.

14. Miscellaneous

14.1 Laboratories A laboratory contains potential sources of release such as hydrocarbon gas samples, and vapours from heated hydrocarbon liquids. Some of the equipment used for hydrocarbon gas and liquid analysis cannot be made suitable for use in a hazardous area (e.g. chromatograph) and therefore shall be considered as ignition sources. Also some leak sources may be toxic for





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health. Adequate ventilation (refer to Section 6.2.4.1.1) shall be implemented in laboratories to ensure that they can be continuously and safely occupied by personnel.

All products contained in laboratories shall be checked for toxicity and flammability. Dilution ventilation rates shall be determined on a case by case basis to take into consideration the hazards specific to each case. The following dilution rates apply only in the laboratories containing no toxic materials and no sources of primary grade of release. They shall be considered by default until the leak rates of secondary grade releases are assessed:

• A laboratory handling flammable gases or liquids shall be provided with an exhaust fan certified for Zone 1, which will achieve adequate ventilation

• A fume cupboard shall also be provided, with an exhaust fan certified for Zone 1 which will achieve a ventilation rate of at least thirty air changes per hour.

Electrical equipment such as fixed lighting, sockets, junction boxes, lighting switches inside the laboratory shall be certified for Zone 2 and defined as per GS EP ELE 079. The inventory of flammable products in laboratories shall be minimised: flammable products other than the minimum quantities necessary for the day-to-day work shall be stored outside the laboratory, in suitable locations.

A laboratory should be a separate building, located in a non-hazardous area. If incorporated in a larger building, it should be completely isolated from other parts of the building. For laboratories where a pressure below that of the surrounding area is maintained, air-locks may be permitted between the laboratory and the remainder of the building. The laboratory ventilation system should be independent from the ventilation of the remainder of the building12.

The doors of a laboratory should be self-closing and of a vapour-tight design.

For the classification of laboratories, see Appendix G1.

14.2 Analyser shelters An analyser shelter or house is a specific closed room or building containing one or more analysers for sampling of flammable fluids which are or may be connected to a process installation together with electrical equipment and auxiliary devices (IEC 60079-16).

The design of analyser shelters shall comply with the requirements of IEC 60079-16, IEC 61285 & present specification. In particular:

• The analyser shelter shall be a separate building or shall be completely isolated from other parts of the building

• If the analyser shelter is located in a hazardous area the ingress of the external atmosphere into the shelter shall be prevented by an internal overpressure produced by forced ventilation (refer to Section 6.2.4.4.1)

• The analyser shelter containing ignition sources (e.g. electrical apparatus not suitable for operation in Zone 2) and secondary grade of release sources shall be provided with dilution ventilation (see Section 6.2.4.1). The dilution ventilation shall ensure thirty air changes per hour as a minimum (IP 15).

12 In certain cases, air inlets may be common to two ventilation systems.





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Continuous or primary grade of release sources shall be vented. Sampling operations which involve the intentional release of flammable substances shall be carried out in a suitable location outside the shelter13. Hydrocarbon vent lines shall be fitted with a flame arrester.

Air intakes for ventilation of analyser shelters should also be taken from outside the hazardous area.

False ceilings and floors shall not be used in analyser shelters. Blowout panels should be provided to minimise the consequences of an explosion.

14.3 Small storage of flammable products This section addresses the case of portable containers with small volumes of flammable products e.g. cylinders containing liquefied hydrocarbons or hydrocarbon gases under pressure (acetylene, LPG). Storage locations shall be identified and designated on layouts during the design of an installation for this equipment such that the hazard of ignition or explosion associated with such storage be minimised.

For the classification of small storage of flammable products, see Appendix G2.

14.4 Loading and filling operations (road tanker, rail car, drum filling) Refer to IP 15, Section 3.

14.5 Jetties (loading, unloading) Refer to IP 15, Section 3.

14.6 Air intakes Air intakes shall be located to prevent ingress of flammable gas or vapour in areas containing ignition sources: e.g. air intakes to heating and ventilation systems and to combustion chambers.

For the classification of air intakes, see Appendix G3.

14.7 Air exhausts For the classification of air exhausts, see Appendix G4.

14.8 Chimneys and exhausts Exhausts and chimneys releasing hot gases shall not be located in hazardous areas Zone 1 or Zone 0.

They may be installed in Zone 2 hazardous areas only if their external skin temperature does not exceed 200°C.

The external skin temperature limits as given above apply to all hot exhaust chimneys and exhausts within the restricted areas of all petroleum installations (for the definition of the restricted area refer to GS EP SAF 253).

For the classification of chimneys & exhausts, see Appendix G5. 13 If a primary source cannot be vented outside the shelter, dilution ventilation shall be provided even if there are no

ignition sources in the shelter (this shall require a derogation to this specification approved by COMPANY and an assessment of the dilution rate).





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14.9 Flares Flares shall be installed in a non-hazardous area.

Flares shall be designed in accordance with GS EP SAF 253 and GS EP SAF 262.

14.10 Traffic

14.10.1 Roads and railways (onshore) For railways, refer to IP 15.

In case requirements of the relevant section of Appendix G6 are not applicable, traffic restrictions shall be implemented based on fixed gas detection which initiates visual and audible alarms (design and risk mitigation measures shall be approved by COMPANY). The safe distances should be materialised by signs wherever an access road enters a hazardous area.

14.10.2 Helidecks, helipads and air strips In case requirements of the relevant section of Appendix G6 are not applicable, traffic restrictions and control procedures shall be implemented based on fixed gas detection which initiates visual and audible alarms, presence of a HLO (Helicopter Landing Officer) or other personnel qualified to authorise landing and take-off (design and risk mitigation measures shall be approved by COMPANY).

14.10.3 Boats In case requirements of the relevant section of Appendix G6 are not applicable, traffic restrictions shall be implemented based on fixed gas detection which initiates visual and audible alarms (design and risk mitigation measures shall be approved by COMPANY).

This requirement covers not only the ship hull and decks but also its chimney, radio aerials and radar antenna and other appurtenances regarded as sources of ignition.

14.11 Purging Purging is the operation of passing a quantity of air through an enclosure and its associated ducts in order to reduce to a safe level any concentration of flammable gas or vapour within the enclosure and its associated ducts (from IEC 60079-16).

The purging process shall last long enough to keep the flammable gas content under 25% of the lowest flammable limit in the worst conditions. In any case the minimum volume of sweeping air shall be five times the total volume of the enclosure/premises. Purging shall be done with air being totally free of flammable gas. This shall be established with flammable gas detectors, fixed or portable. For the precautions specific to the operation of fired heaters refer to GS EP SAF 227.

Care shall be taken that all areas have been effectively purged, particularly the confined areas such as:

• Pits, if heavier than air gas or vapour is present

• Ceiling recesses if lighter than air gas or vapour is present

• Blind corners.

Flammable gas detectors shall be used to check all spots where gas is likely to accumulate.





Page 35/73

14.12 Classification of enclosed buildings The classification of the enclosed buildings shall be based on the rules defined in present specification (refer to Section 7.3), with due consideration for ventilation and pressurisation (as per Section 6.2.4) and in conformity with the relevant section of Appendix G.




Annex 1


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Annex 1 Table of hazardous equipment

Hazardous equipment Flammable fluid Area Source of release Classification Remark

Tag number

Description Phase MW T

°C

P

bar(a)

Flash

Point °C

Cate-gory

Den-sity

Auto ignition

T°C

Explosive limits

% LFL

% UFL

Type Ventilation Nature Grade Flow

m3/h

Zone Hazard radius

m

Gas group

Temp class

V 110 Separator Vapor

(5)

22

(1)

50

(2)

75

(2)

-

(3)

G(i) L 502 4%

16%

Shel-tered

Adequate Instru-ment vent

2 -

(4)

2 7.5 II A T3

(1) Range of MW to cover all situations.

(2) Design pressure and design temperature or the most critical combination of P and T for hazardous releases.

(3) For liquids only.

(4) Only for vents that are covered by this specification (see Appendix A).

(5) Vapours from a release are to be considered either heavier (H) or lighter than air (L).




Annex 2


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Annex 2 Area classification procedure

This procedure shall be followed at each stage of a development project and whenever there is a modification to an existing installation.

Equipment

Zone ranking- § 6.2

Location - Open, sheltered, enclosed area -§ 6.2.3, 6.2.4 & 7

Ventilation - § 6.2.4

Hazard radius - § 8.2 to 8.4 & Appendix A Direct example method - § 10, 11, 12, 13 & 14 & Appendices A & B gives hazardous radius &

envelope at once

Hazardous area envelope - § 9 & Appendices A & B

Grade of release - § 6.2.1

Fluid category - § 8.1




Annex 3


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Annex 3 Procedure for assessing type & degree of ventilation

This method for assessing type and degree of ventilation applies in areas where sources of flammable gases are present. Where toxic gases may be released, the ventilation rates given in the figure are not relevant.

Determine openness of region to be classified by inspection of installation layout

Open AreaOpen air conditions (wind speed rarely

< 0,5 m/s and frequently > 2 m/s

Enclosed Area

Are there any significant obstacles

to natural wind ventilation?

Does enclosed area contain internal source of release?

If external source exists is enclosure

pressurised to > 25 Pa

Consider general or local artificial

ventilation

Does ventilation system give >12 air changes per hour?

Are there sufficient air changes to give

dilution ventilation at all ignition sources?

Open area:

Adequate

Natural ventilation

Over pressurized

enclosed area:

Non hazardous

Enclosed area:

Dilution ventilation

Enclosed area:

Adequate ventilation

Enclosed area:

Inadequate ventilation

No Yes No

No

Yes

Yes

Yes

No

Yes No Sheltered

or obstructed

area:

Restricted natural

ventilation




Annex 4


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Annex 4 Guidelines for the determination of the level of ventilation of sheltered areas

Guidance from this table is broadly in line with API RP 505 (Section 6.6, first edition 11/1997, reaffirmed 11/2002).

The buildings described below are regarded as sheltered areas and may be used as weather protection for equipment handling flammable fluids:

• Buildings where walls height is less than 2.5 m above ground, and the space under the roof is adequately ventilated

• Buildings where the walls are provided with louvers or other types of slits purposely designed for ensuring that natural ventilation will be adequate. As a minimum the louvers should be present on three (out of the four) sides of the building: two strips of louvers, each with a minimum vertical width of 1 m, shall run along the full length of the wall, one at the top i.e. close to the roof/ceiling, the other at the bottom i.e. close to the floor/ground. It should also be checked that these buildings offer a sufficient free area of inlet openings as per the formula given in Section 6.6.2.4.6 of API RP 505.

Walls (% surface) (2)

> 0 to 25 > 25 to 50 > 50 to 75 > 75 to 100

Top & bottom parts Type of ventilation

Floor + ceiling Adequate Inadequate (3) Inadequate Inadequate

No floor (1) + ceiling Adequate Adequate Inadequate Inadequate

Floor, no ceiling Adequate Adequate Adequate Inadequate

No floor (1), no ceiling Adequate Adequate Adequate Adequate

(1) Gratings are regarded as no floor

(2) Plain walls (no louvers)

(3) In some cases may be regarded as adequate.




Appendix A


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Appendix A - Determination of hazard radii values for equipment

For further guidance, see Section 5 & Annex C of IP 15 - 3rd Edition - July 2005.

All distances in this section are given in metres.

The maximum hazard radii for categories A, B, C and where appropriate G(i) & G(ii) are given in the following tables.

Hazard radii are given using dispersion calculation methodology applied to particular fluid compositions; however, a more accurate value of hazard radius may be determined using dispersion models which take into consideration all the actual physical properties of the gas, characteristics of the environment and conditions of release.

Gas dispersion calculations, if necessary, shall be carried out as per GS EP SAF 253, using codes (computer programs) approved by COMPANY.

Where appropriate, a risk based approach may be used to determine release hole size (see Appendix A2).

The risk based methodology provides a means of adjusting release frequency and hence hazard radii, to fit specific process scenarios.

A1. Equipment/arrangements generally generating continuous or primary grade releases

A1.1 Drains & liquid sample points This section applies to process equipment drains, instrument drains and liquid sample points that discharge directly to atmosphere.

Drains and sample points should be graded based on the expected frequency of use.

If used more than once a day they should be regarded as primary sources as a minimum.

The following rules shall apply:

• Draining and sampling of Category A liquids shall not be done directly to atmosphere.

• They shall require a closed collection system, designed to be safely vented to an appropriate disposal system such as a flare (refer to GS EP SAF 262 for the design of hydrocarbon disposal systems, and GS EP SAF 228 for the design of closed drain systems).

• Draining and sampling of Category B liquids directly to atmosphere should be avoided: Wherever feasible, draining should be done to a closed drain system. Samples should be taken in a sealed container designed to be connected to the drain point for the duration of the sampling. There shall be a hazardous area resulting from the flanges and the valves (see Appendix A2.3).

• Equipment drains (with the exception of the instrument drains) shall be designed as per GS EP SAF 228. As such they are normally blinded and used only after the equipment is isolated and depressurised. They generate a hazardous area as for valves and flanges (see Appendix A2.3). If for any reasons equipment drains were not blinded they would generate hazard radii as per Table A1 and in this case the possibility for draining category B liquids shall be considered.




Appendix A


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• Sampling of gases to an open system, i.e. with a release to atmosphere, shall generate a hazard radius equivalent to an instrument vent (Appendix A1.4 applies).

• Sampling to a closed system with normally no release to atmosphere shall generate a hazard radius as for flanges and valves (Appendix A2.3).

In all other cases, in particular the instrument drains and sampling of liquids to an open system, Table A1 gives the maximum hazard radius for fluid categories A, B & C for the “worst case” discharge pressure. The hazardous area will extend from the point of draining/sampling.

Table A1 - Drains (not blinded) and liquid sample points

Hazard radius R1 (in m) Fluid

category Pressure (Bar(a)) Diameter (2)

2 mm Diameter (2)

5 mm Diameter (2)

10 mm Diameter (2)

20 mm

A 100 (3) (3) (3) (3)

B 100 4 10 20 (1)

C 100 5 12 22 (1)

(1) For this diameter the radius exceeds 30 m. The size of the potential release is greater than normally considered for area classification and should be avoided. Alternative design options should be considered such as a closed collection system (refer to the text of this section), or a smaller diameter (e.g. a restriction).

(2) This is the diameter of the smallest item on drain or sample line i.e. line, valve or restriction orifice.

(3) Draining and sampling of Category A liquids directly to atmosphere shall not be allowed.

A1.2 Tank vents (category C fluid) Freely vented tanks will allow vapour /air mixtures to be released in normal operation.

Table A2 gives the hazard radii from the storage tank vent of a typical category C fluid:

Table A2 - Tank vents

Hazard Radius R1 (in m)

Vent Diameter (in mm) Vent rate (Nm3/h)

50 80 100 250

250 2 2 2 3 500 3 3 3 4

1000 3 4 4 6 2500 4 5 5 6

A1.3 Process vents Permanent or occasional outflows of combustible vapour shall be collected and discharged away from possible sources of ignition.

All vent flow-rates in this section are given at Normal conditions.




Appendix A


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Material that could condense shall not be vented directly to atmosphere.

Vents shall be classified as continuous, primary or secondary grades of release depending on the frequency of operation. Vents used frequently (e.g. daily) should be classified as primary grade as a minimum.

For some vents there may be a small continuous or primary grade release flow (generating a Zone 0 or 1) with a larger secondary grade release occasional flow (generating a Zone 2) for example during abnormal or emergency operation. In this case, the Zone 0 or 1 hazardous area shall be surrounded by a larger Zone 2 area defined by the larger flow (refer to Appendix B).

The hazard radii for process vents have been calculated for a matrix of venting rates and vent diameters for a lighter and a heavier than air release and are given in Table A3.

The peak venting flow rate of the release is to be considered for determining the hazard radius.

These recommended distances are based on unrestricted upward discharge and dispersion of vapour without condensation.

Table A3 - Process vents

Hazard Radius R1 (in m)

Vent diameter (mm) Vapor Emission rate (Nm3/h)

50 100 250

10(1) (3) 3 5 6

100(1) (2) 3 5 6

250(2) 3 5 6

500(2) 4 5 7

1000(2) 5 5 9

(1) For vents with flow rates kept below 100 Nm3/h and where the velocity of all the releases are above 150 m/s, the distance to LFL given in API STANDARD 521(Section 6.3 fifth edition 01/2007) should be adopted.

(2) For vents with flow rates exceeding 200 Nm3/h a dispersion calculation shall be carried out to check if the distances of this table are adequate (gas dispersion calculations shall be carried out as per GS EP SAF 253). A dispersion calculation is also recommended for vents with flow rates exceeding 100 Nm3/h.

(3) Gaseous sample points should be designed so that the flow rate is less than 10 Nm3/h at ambient conditions. It may be necessary to fit a flow restrictor on high pressure systems.

A1.4 Instrument vents The maximum hazard radii from vents on instrument systems shall be based on Table A4 which gives the maximum hazard radius for fluid categories A, B, C, G(i) & G(ii) for the “worst case” discharge pressure of 100 bar(a).




Appendix A


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Table A4 - Instrument vents

Hazard radius R1 (in m) Fluid

category Diameter 1 mm

Diameter 2 mm

Diameter 5 mm

A 2.5 4 9

B 2 4 9

C 2.5 4.5 9

G(i) <1 <1 1

G(ii) 1 1 2

A1.5 Sumps in oily water treatments units The typical layout of a sump is shown in Figure A1.

The hazardous area above ground and outside the sump walls should be drawn as shown from the periphery of the sump using the appropriate hazard radius obtained from Table A5 in cases when it can be assumed that entry of only Category C fluids can occur.

Generally this assumption can be made only in the case of storage and tank areas, including installations and depots.

This area should be classified as Zone 1 or Zone 2 depending on whether the source is primary or secondary grade of release.

When there is a possibility that hot material could enter the sump in sufficient quantity to produce appreciable quantities of gas, or that Category A or B material could inadvertently enter, then a hazard radius of 15 m should be used with an increased vertical distance of 3 m.




Appendix A


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Note 1: The Zone 2 is applicable where there is a possibility of a secondary grade release and

the hazard radius R, for the primary grade release is less than 15 m.

Note 2: Dimension from table 5.

Note 3: h depends on the temperature of release and the volatility of the material released. For Category C fluids up to 50°C, h is nominally 1 m; for volatile fluids or at elevated temperatures, a nominal height, h, of at least 3 m should be applied. However it is recommended that this height is verified by calculation.

Note 4: For a secondary grade release, the area shown as Zones 0 and 1 would be Zones 1 and 2 respectively.

Figure A1 - Open sump - Zoning shown for primary grade source

Table A5 - Sumps (all distances in meters)

L R1

Less than 5 5 to less than 10 10 or greater

3

7.5

15

Note 1: This table should be used only for Category C liquids.

Note 2: L is width of the sump. The hazardous area should extent from the edge of the pool.

A1.6 Pig receivers and launchers Pig receivers and launchers are likely to be opened frequently and should normally be regarded as sources of primary grade release. The hazardous area should be classified as Zone 1.

The design of the pig traps shall be such that they cannot be opened while under pressure; this is normally achieved by a mechanical interlock between the door mechanism and the drain or vent systems. A pressure gauge shall be provided with a range suitable for checking zero pressure before opening the door.




Appendix A


Page 45/73

On this basis, the doors of the pig traps should be regarded as sources with a hazard radius (Zone 1) of 3 m around the trap door.

This distance may be reduced to 1.5 m if the equipment is purged with nitrogen and water washed through before opening.

On pig receivers and launchers without an interlock between the door mechanism and the drain or vent systems, there should be an additional Zone 2 area from the trap door with a hazard radius of 6 m.

Vents and drains should discharge to a safe location and the hazard radius they generate shall be estimated using Appendices A1, 2, 3 & 4.

A2. Equipment/arrangements generally generating secondary grade releases

A2.1. Pumps LNG pumps, for which motor and pump are submerged in a “can” or in a storage tank, do not generate a hazardous area.

Sources of release on pumps include their seals, vents, drains, valves, piping flanges and filter/strainers.

They are normally all secondary grade sources because flanges are broken, filters opened and vents and drains operated infrequently. Likewise a seal failure resulting in an appreciable release of liquid is unlikely. Should any of these events be part of “normal operation” (as defined in Section 3) or occur frequently then the item should be regarded as an individual primary grade source.

The hazardous area generated by the pump should be drawn from the periphery of the pump. For this purpose the term "pump" should include the associated equipment which can be source of release.

Vents and drains which are not blinded in normal operation generate their own hazardous areas, independently from the pump they are associated with.

Hazard radii may be read off Table A6 that gives the maximum hazard radii for fluid categories A, B & C for the “worst case” discharge pressure of 100 bar(a):

Table A6 - High Integrity Pumps

Fluid category Hazard Radius (in m)

A 6

B 5

C 6

The term "high integrity" refers to a pump for which the design reduces significantly the probability of release. The pumps of glandless type, or fitted with a double mechanical seal system with a means of detecting leaks through the inner seal should be regarded as “high integrity pumps”.

For non high integrity pumps (single seal with or without throttle bush), refer to IP 15 3rd edition -Annex C - Calculation of hazard radii.




Appendix A


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A2.2 Compressors Sources of release on compressors include seals, glands and joints. The hazardous area should be drawn from the periphery of the unit.

Vents and drains which are not blinded in normal operation generate their own hazardous areas, independently from the compressor they are associated with.

Hazard radii may be read off Tables A7 & A8 that gives the maximum hazard radii for fluid categories G(i) & G(ii) for the “worst case” discharge pressure of 100 bar(a):

Table A7 - High Integrity (dry gas seals) compressors

Fluid category Hazard radius (in m)

G(i) 1

G(ii) 2.5

Table A8 - Non dry gas seals reciprocating compressors

Fluid category Hazard radius (in m)

G(i) 2

G(ii) 3

For non dry gas seals centrifugal compressors (purged labyrinth or floating ring seals), refer to IP 15 3rd edition - Annex C.

A2.3 Piping, instrument tubing, flanges & valves Hazard radii are from the periphery of flanges and valves in piping and instrument tubing.

All-welded (without fittings such as valves, instruments and flanges) piping and instrument tubing designed and constructed to COMPANY specifications should not be considered as sources of release.

Flanges routinely broken in normal operation e.g. with a frequency greater than once a week, should be considered as primary grades of releases.

All valves shall be considered as sources of release.

Blow out of part of a gasket has not been considered since it is regarded as an incident with a low probability that is considered in consequence analysis for the determination of fire zones (refer to GS EP SAF 253).




Appendix A


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Hazard radii may be read off Table A9 that gives the maximum hazard radii for fluid categories A, B, C, G(i) & G(ii) for the worst case discharge pressure and a release hole diameter of 1 mm:

Table A9 - Flanges and valves

Fluid Category Hazard radius (in m)

A 3

B 3

C 3

G(i) 1

G(ii) 2




Appendix B


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Appendix B - Sizing of hazardous zones

The relationship between the hazard radius R1 and the full 3-dimensional envelope of the hazard Zone is determined using the following figure:

(c) Releases where H > R1 +1

Figure B1 - Shape factors for pressurised releases The shape factor depends upon the height and orientation of the release and the hazard radius.

The key features are:

• Releases below (H) of 1 m are influenced by the ground and have a hazard radius R2

• Releases above 1 m, but at heights below the hazard radius R1 + 1 m are influenced by the ground if the release is directed downward and passes below 1 m

• Releases at height above the hazard radius R1 + 1 m are independent of the ground.




Appendix B


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The ground effect R2 can be estimated from the hazard radius R1, directly using Table B1:

Table B1 - Hazard Radii at ground level R2

Hazard radius R2 (m)

Release hole diameter Fluid category

Release Pressure

(bara) 1 mm 2 mm 5 mm 10 mm A 5

10 50

100

2 2.5 3 3

4 4.5 5.5 6

16 20 20 20

(1)

(1)

(1)

(1) B 5

10 50

100

2 2.5 2.5 3

4 4 5 5

14 16 17 17

(1)

(1)

(1)

(1) C 5

10 50

100

2.5 2.5 3 3

4 4.5 5.5 6

20 21 21 21

(1)

(1)

(1)

(1) G(i) 5

10 50

100

<1 <1 <1 1

<1 <1 1.5 2

1 1.5 3.5 5

2 3 7

11 G(ii) 5

10 50

100

<1 <1 1 2

<1 1 2 3

2 2.5 6 8

4 5

11 14

(1) For this diameter the radius exceeds 30 m. The size of the potential release is greater than normally considered for area classification and should be avoided.




Appendix B


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Note 1: Vent pipe opening should have at least R1 metres of free space around it in all

directions to allow dispersal of vapour, and be away from open windows, doors, etc.

Note 2: To avoid placing a working platform in a Zone 1 area, h should be measured from any working level within R1 metres of the vent stack.

Note 3: In (c), R1 for Zone 1 should be for the primary grade release and R1 for Zone 2 should be for the secondary grade release.

Figure B2 - Typical hazardous areas around vents




Appendix C


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Appendix C - Drilling rigs, equipment and well operations

C1. Foreword This section sets out onshore and offshore COMPANY requirements for the area classification of:

• Drilling, workover and pulling operations on Non Live Wells

• Well servicing operations on Live Wells

• Wellheads in production operations.

It does not cover the production equipment located downstream of the wellheads.

C2. Drilling, workover and pulling operations on Non Live Wells Classification of areas for drilling, workover and pulling operations on Non Live Wells, on single and clustered wells for an onshore or offshore location is shown on Figures C1 to C4, based on the potential sources of hydrocarbon release at:

• The rig substructure (from rig floor to main platform deck - offshore - or ground level - onshore-) in which the bell nipple, diverter and blow out preventers are located

• The wellhead area down to the cellar

• The upper works of the rig, above the rig floor

• The circulating surface mud system

• Tanks, flanges, vents or drains

• Gas vents from any of the above.

In an open area a spherical hazardous area (Zone 1) of 3 m radius shall extend from the centre of the bell-nipple.

A hazardous area (Zone 2) surrounding the spherical 3 m radius hazardous area shall extend 7 m vertically and horizontally from the spherical area envelope and down to ground or sea level.

Hazardous areas from miscellaneous sources such as vents, drains, valves and flanges on the BOP, its stack and the riser assembly will conservatively be within the hazardous area shown on Figures C1 to C4. Alternatively, they can be determined as per the relevant sections of Appendices A & B.

The occurrence of a blow-out or a ‘kick’ is not considered in this area classification specification. Kicks are regarded by COMPANY as rare and accidental events because mud degassing equipment, continuous monitoring of pit level, hydrocarbon gases level and gas extraction is mandatory on its drilling and work-over rigs.

On drilling installations, the "dog house" and all other technical facilities shall be classified as Zone 2.

Generally, sheltered areas shall generate a hazardous area extending 3 m outside the shelter (beyond the 10 m from the bell-nipple if necessary). Any apertures from an enclosed area containing a source of release should be regarded as a secondary grade source and the resulting hazardous area should be drawn from the apertures.




Appendix C


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If the derrick is enclosed, and if it contains a secondary grade source of release (e.g. flanges, valves in hydrocarbon pipes) the internal space shall be classified as Zone 1, with a Zone 2 extending 3 m outside the enclosure.

If the sub-structure is enclosed and if it contains a secondary grade source of release (e.g. flanges, valves in hydrocarbon pipes), the internal space should be classified as Zone 1 with a Zone 2 extending 3 m outside the enclosure or 10 m from the bell-nipple whichever is greater. All electrical equipment on the drilling mast shall be suitable for Zone 2 as a minimum (sufficient if the derrick is adequately ventilated).

All electrical equipment needed for controlling drilling operations in an emergency (i.e. kick, blow out) shall be suitable for Zone 1.

C3. Surface mud systems Open tanks should be regarded as sumps. The larger of the distances indicated in Appendices A & B and those defined in this chapter shall be used to define the hazardous zones.

The surface mud system includes the mud circulating pumps, the shale shaker area and the setting tank, together with any mud degassing equipment.

The possibility of the mud being itself hazardous shall be considered. A mud shall be considered hazardous whenever its temperature may reach its flash point or the auto-ignition temperature during:

• Storage or

• Circulation (as a result of high subsurface temperature and/or mixing with reservoir hydrocarbons) or

• Upon release (e.g. heated by sun radiation, other hot objects or when spray atomisation leading to mist formation can occur).

Advice from geologist should be obtained to estimate the maximum operating temperature of the mud.

Mud pumps and manifolds in the surface mud system should normally not be regarded as sources of release.

Typical hazardous areas around mud tanks and shale shakers located in open areas are shown on Figures C5 & C6.

In an open area, the space within the mud tank walls shall be classified Zone 1 with a Zone 2 area outside (See Figure C5).

In an open area, a shale shaker should generate a horizontal Zone 1 area and an additional Zone 2 extending from Zone 1 (See Figure C6).

When a shale shaker or a mud tank is located in an enclosure with adequate artificial ventilation, the enclosure should also be classified as Zone 1 extending 3 m from any opening.

Enclosures containing a mud tank should, unless there is adequate (artificial) ventilation, be classified as Zone 1, with an additional Zone 2 area extending 3 m from any openings in the enclosure.




Appendix C


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C4. Rig gas vent Primary grade sources of release such as vent line outlets shall not be allowed within an enclosed area (derrick or the shielded portion of a derrick).

Vents should not be released directly to atmosphere i.e. they should be collected in a purposely designed system discharging at a safe location (away from ignition sources, refer to Appendices A & B).

The gas vent outlet of the main mud system shall be located at the top of the derrick (outside the enclosure if the derrick is enclosed) or be remote from the drilling area.

When the maximum anticipated vent rate can be estimated, then the extent of the hazardous area should be based on the recommendations on process vents given in Appendices A & B.

When this information is not available, the hazardous area shall extend at least 15 m in all directions from the vent.

With a vent at the derrick top, any area within the derrick less than 15 m from the vent shall be considered hazardous.

The gas vent should normally be considered as a source of primary grade release.

C5. Well servicing (Wire-line - Coiled tubing - Snubbing) operations on Live Wells Area classification for well servicing operations (wire-line - coiled tubing - snubbing) on Live Wells is shown on Figures C7 and C8 based on the potential sources of hydrocarbon release on surface and at the source point of release.

C6. Wellheads in production operation Area Classification for production operations are shown on Figures C9 and C10.

For an onshore well, the ground cellar is classified as Zone 1 for all servicing and production operations.




Appendix C


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Figure C1 - Offshore single wellhead during operations on Non Live Wells

(drilling, workover & pulling)




Appendix C


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Figure C2 - Offshore cluster wellhead during operations on Non Live Wells

(drilling, workover & pulling)




Appendix C


Page 56/73

Equivalent diameter of pool L(m)

Hazard radius R1(m)


3

7.5

15

Figure C3 - Onshore single wellhead in operations on Non Live Wells (drilling, workover & pulling)




Appendix C


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Equivalent diameter of pool

L(m) Hazard radius

R1(m)


3

7.5

15

Figure C4 - Onshore cluster wellhead in operations on Non Live Wells (drilling, workover & pulling)




Appendix C


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Figure C5 - Hazardous area around mud tanks

Equivalent diameter of pool

L(m) Hazard radius

R1(m)


3

7.5

15

Figure C6 - Hazardous area around a shale-shaker in an open area




Appendix C


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Note 1: For a non eruptive well, the Zone generated by the wellhead and the well service

equipment can be considered Zone 2

Note 2: Source point of release is at stuffing box for wireline, head injection for coiled tubing and bowl stripper for snubbing

Figure C7 - Offshore wellhead during well servicing operations on Live Wells (wireline-coiled tubing - snubbing)




Appendix C


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Note 1: For a non eruptive well, the cellar remains classified Zone 1 but the Zone generated by

the wellhead and the well service equipment can be considered Zone 2.

Note 2: Source point of release is at stuffing box for wireline, head injection for coiled tubing and bowl stripper for snubbing

Equivalent diameter of pool L(m)

Hazard radius R1(m)


3

7.5

15

Figure C8 - Onshore wellhead during well servicing operations on Live Wells (wireline - coiled tubing - snubbing)




Appendix C


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Figure C9 - Offshore wellhead - Production or injection (open area)

Note: In the case of a beam-pumped well, the release source to be considered is the stuffing

box.

Equivalent diameter of pool - L(m) Hazard radius - R1(m)


3

7.5

15

Figure C10 - Onshore wellhead - Production or injection (open area)




Appendix D


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Appendix D - Gas turbines

This section sets out the COMPANY specific requirements for the classification of gas turbines.

The following figures (Figures D1 to D3) give details for each typical case:

• Ventilation and pressurisation requirements

• Hazard radii around the vents outlets.

Figure D1

• Gas turbine driving a compressor within a safe area

• Gas turbine driving a generator within a safe area.

Figure D2

• Gas turbine driving a compressor in a unit room within a Zone 2 hazardous area

• Gas turbine driving a generator in a unit room within a Zone 2 hazardous area.

Figure D3

• Gas turbine driving a compressor in a unit room within a safe area

• Gas turbine driving a generator in a unit room within a safe area.




Appendix D


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Figure D1 - Turbine enclosure without unit room in a safe area




Appendix D


Page 64/73

Figure D2 - Turbine enclosure within a unit room in a hazardous area




Appendix D


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Figure D3 - Turbine enclosure within a unit room in a safe area




Appendix E


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Appendix E - Gas/liquid fuel engines & heaters

E1. Gas engines Offshore, gas engines shall be installed in a pressurised enclosure with dilution ventilation in accordance with the requirements of Section 6.2.4. Onshore, the above requirement is not mandatory if a package comprising one engine, its driven equipment and their “auxiliaries”14 is installed at a distance d of:

• At least 30 m or more from the hydrocarbon process and storage facilities and their technical rooms, and

• At least 45 m or more from LPG units, and

• At least 45 m or more from the installation main control room, and

• At least 60 m or more from the living quarters, offices and workshops.

Ignition sources should be made suitable for Zone 2.

E2. Diesel engines Onshore, a diesel fuel engine installed in Zone 2, not in conformity with EN 1834-1 and not installed in an overpressurised enclosure, its driven equipment and their “auxiliaries” shall be installed at a distance d of:

• At least 30 m or more from the hydrocarbon process and storage facilities and their technical rooms, and

• At least 45 m or more from LPG units, and

• At least 45 m or more from the installation main control room, and

• At least 60 m or more from the living quarters, offices and workshops.

Ignition sources should be made suitable for Zone 2.

Process vessels shared by several diesel engine driven compressors or pumps shall be considered as a separate unit, distinct from the diesel engines' and associated driven equipment.

All diesel engines and driven equipment shall be grouped together in one functional unit separated from other units (process or utility) by minimum distances as per GS EP SAF 021.

Diesel engines in hazardous areas driving different type of equipment (e.g. compressors and pumps) shall be grouped in different units segregated as per GS EP SAF 021.

14 Process facilities and technical rooms shared by several gas engines such as the fuel gas treatment unit are not

regarded as “auxiliary” and shall be installed at the distance specified above. Several engine driven packages of the same type and function may be grouped in the same unit (refer to Figure E1).




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Unit edge

ENGINE

ENGINE

ENGINE

Unit edge

Haza

rdous area boundary encroaching onto enginesd

d = defined in Appendix E Sections 1 & 2

Figure E1 - Diesel and gas engines in a hazardous area onshore

E3. Fired heaters The extent and classification of hazardous areas around fired heaters and other fuelled utilities shall be based upon the following principles:

• Any fuel gas line (s) and appurtenances (flanges, filters, valves, instrument tapping) shall generate a Zone 2 with a radius of 3 m

• Any valve, set of flanges on the liquid-fuel network shall generate a Zone 2 of a radius of 3 m

• Main burners, igniters and pilots shall be located at least 3 metres off of the closest joint pertaining to the fuel gas system and from any process flanges

• Any equipment within a radius of 1.5 metre around the main burners, igniters and pilots shall be suitable for use in Zone 2.




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Non hazardous area but material suitable for Zone 2 required

Figure E2 - Hazardous areas around fired heaters




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Appendix F - Hydrocarbon storage

F1. Overhead, fixed roof storage tanks For fixed roof storage tanks containing liquids of Classes I, II (2) or III (2) that are normally of Category C on release, the extent and classification of the hazardous areas shall be as shown below:

Zone 0 2 m

3 m

3 m

Zone 1

Zone 2

Pit, if any, Zone 1

Figure F1 - Fixed roof storage tank (Fluid class I, II (2) and III (2))

Liquids of Classes II (1) or III (1) or unclassified are normally non-hazardous on release. Considering however the possible changes in ambient temperature, and that the flash-point of heavy fuels or bitumen in heated storage is not reliable, it is recommended to classify the ullage space as Zone 0, with a small Zone 1 around roof vents and openings.

Zone 0

1 mZone 1

Figure F2 - Fixed roof storage tank (Fluid class II (1), III (1) or unclassified)




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F2. Overhead, floating roof tank (Category C on release) For floating roof storage tanks containing liquids of Classes I, II(2) or III(2) that are normally of Category C on release, the extent and classification of hazardous areas shall be as shown below:

Zone 1

2 m

2 m

Zone 2

Pit, if any, Zone 1

Figure F3 - Floating roof storage tank (Fluid class I, II(2) or III(2))

F3. LPG storage stored under pressure

5 m

7.5

m

7.5 m 7.5 m

Ground

Storage vessel Capacity < 200 m3

PSV dischargeassumed to be at this location

Zone 2

Zone 1

7.5

m

Figure F4 - LPG storage vessel < 200 m3




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Ground

Storage vessel Capacity > 200 m3

PSV dischargeassumed to be at this location

10 m0.6 m

Zone 2

Zone 1

15 m

Figure F5 - LPG Storage vessel > 200 m3

Notes on figures F4 and F5:

• The figures are the cross-sections of the LPG storage vessel which contain the Pressure Safety Valve (PSV) discharge point. The Zone 1 envelope is a sphere centred on the PSV discharge point, and the Zone 2 envelope is made of cylinders with a vertical axis containing the PSV discharge point

• The size and shape of the hazardous areas are determined by the location of the storage vessel and the volume of the vessel containing LPG under pressure (less or more than 200 m3). They do not depend on the shape of the storage vessel (sphere, cylinder)

• The hazardous areas generated by piping connections, sample points, instrument vents and all other equipment shall be determined as per the standard rules given in Appendices A & B.




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Appendix G - Miscellaneous

G1. Laboratories The hazardous areas generated by the doors (vapour-tight or not) and the fan exhausts shall extend to 3 m as shown in Figure G1.

3 m

Adequate ventilation

Laboratory

3 m

Self-closing airtight door

ZONE 2

Exhaust fan creating under pressure

Figure G1 - Laboratories

G2. Small storage of flammable products Since a leak from properly designed containers can only be accidental, such containers should generate a hazardous area Zone 2, extending X m from the envelope of the containers(s). X should be determined as per Table A9 of Appendix A2 - Flanges and valves.

G3. Air intakes Air intakes shall be located at least 2 m away from the border of any hazardous area.

G4. Air exhausts Air exhausts from a classified enclosed area should generate a hazardous area of 3 m radius with the same classification as the enclosed area.

G5. Chimneys and exhausts Chimney outlets shall be at least 2 m away from the border of any hazardous area Zone 2 and 9 m away from the border of any hazardous areas Zone 1 or 015.

G6. Traffic

G6.1 Roads & railways The main roads of a plant (peripheral roads) shall be kept no less than 2 m away from the border of any Zone 2 and 9 m away from the border of any Zone 1 and Zone 0.

G6.2 Helidecks, helipads and air strips Any point of these areas as well as any area being part of a helicopter/plane approach Zone shall be no less than 2 m away from the border of any Zone 2 and 9 m away from the border of any Zone 1 and Zone 0.

15 Vents from turbine lube oil tanks, although generating a Zone 1 hazardous area, may exit into the outlet of the turbine main

exhaust chimney. This standard design is regarded as safe considering the risk specific to this situation.




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G6.3 Boats The boat landing and/or the mooring facilities shall be such that tugs or supply boats are kept 2 m away from the border of any hazardous area Zone 2 and 9 m away from the border of any hazardous areas Zone 1 and 0.

G7. Enclosed buildings: This section is intended to provide examples of the application of these rules, as shown in Figure G2.

Note 1: Zone classification and extent to be defined according Appendices A & B assuming the

door is wide open. Installation of self-closing airtight door is recommended.

Figure G2 - Classification of enclosed buildings