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Reference
HSE-TSSA-05-2011
Document Title
WELDING, CUTTING AND HEATING
SAFE WORK PRACTICES
Reference: SHE-TSSA-05-2011 / Rev.- 3 Date of Issue: November
2009
Title: Welding, Cutting and Heating Safe Work Practices Next
Review Date: November 2012
Printed Copy Not ControlledKUWAIT NATIONAL PETROLEUM COMPANY
Page 2 of 24
WELDING, CUTTING AND HEATING
SAFE WORK PRACTICESTABLE OF CONTENTS
PAGE
1.0 2.0 3.0 4.0
Scope and Application.... References. Definitions. Hazards,
Precautions and Safe Work Practices 4.1 4.2 4.3 4.4 4.5 Welding and
Cutting Hazards .. General Precautions .. Enclosure of Welding and
Cutting Area Fire Watch Personnel Personal Protection ... Gas
Welding and Cutting. Electric Arc Welding and Cutting Other Welding
and Cutting Techniques .
3 3 4
6 7 9 10 11 12 13 15 16 18 18 19
5.0
Welding Works Classification and Requirements 5.1 5.2 5.3
6.0 7.0 8.0 9.0
Preheating and Heat Treatment (Stress Relieving) Hot Tapping on
Live Piping and Equipment Tie-in on Hydrocarbon Contaminated Lines
Audit Requirements . APPENDIX
Appendix - A Appendix B Appendix C
: Filter Lens Shade Numbers .. : Flashback Arrestors and Hose
Check Valves : Tarpaulin Canvass Cloth Selection Criteria.
20 21 22
Reference: SHE-TSSA-05-2011 / Rev.- 3 Date of Issue: November
2009
Title: Welding, Cutting and Heating Safe Work Practices Next
Review Date: November 2012
Printed Copy Not ControlledKUWAIT NATIONAL PETROLEUM COMPANY
Page 3 of 24
1.0
SCOPE AND APPLICATIONThis document outlines the principles
involved and the precautions to be taken in welding, cutting and
heating work activities in KNPC premises. These activities are
considered safe if they are carried out in a controlled manner by
complying with the recommended safety precautions. The Safe Work
Practices covered in this document include safety issues in gas and
arc welding as well as flame cutting in detail. It briefly covers
other modern cutting techniques such as hydrojet and plasma
cutting. Reference for hot tapping and welding (including patch
work and box welding) on live lines, tie-in on contaminated lines,
and heat treatment have also been incorporated. The principles and
resources provided in this document are widely applicable. Some
activities may be subject to specific regulations or unique work
requirements which should be considered when developing welding,
cutting or heating program and activities. Personnel doing welding,
cutting and other hot work require a high degree of skill and shall
be qualified for the work they are doing. This document does not
replace a welding manual. The qualification of personnel falls
outside the scope of this document. Mandatory rules (or must) are
characterized by the word SHALL throughout the text. Advisory rules
or recommendations are indicated by the word SHOULD.
2.0
REFERENCES National Safety Councils Accident Prevention Manual
KNPC Inspection Procedure IC-18 (Inspection of Hot Tapping and
Welding on Equipment and Piping), IC-23 (Welder Performance
Qualification and Electrode Approval Procedure), IC-24 (Post Weld
Heat Treatment for Piping) and IC-25 (Welding Manual) API RP 2201
(Safe Hot Tapping Practices in the Petroleum and Petrochemical
Industries) API RP 2009 (Safe Welding, Cutting, and Hot Work
Practices in the Petroleum and Petrochemical Industries) OSHA
1910.252 Welding, Cutting and Brazing KNPC PPE Specifications KPC
Document 49: Eye and Face Protection
Reference: SHE-TSSA-05-2011 / Rev.- 3 Date of Issue: November
2009
Title: Welding, Cutting and Heating Safe Work Practices Next
Review Date: November 2012
Printed Copy Not ControlledKUWAIT NATIONAL PETROLEUM COMPANY
Page 4 of 24
3.0
DEFINITIONSAir-Tight Enclosure means that (a) sparks and molten
metal/splatters are completely contained and (b) the natural air
circulation is blocked which will contribute to an accumulation of
toxic gas emanating from the electrodes or an inert condition
caused by inert gas shielding process during welding and cutting
works within the enclosure. Fire Watch is a person assigned in
welding works to cover safety surveillance and response function on
emergency situation, including first-aid fire fighting. First-Aid
Fire Fighting is a practical training on the use of fire
extinguishers, fire hose and couplings, foam making equipment,
operation of plant paging and fire alarm call points, and use of
other first-aid fire fighting equipment available in KNPC premises.
Flameproof Tarpaulin Canvass is a cloth (glass fiber based or
silica fiber based) used for welding work fire protection which
does not burn or give off fumes when exposed to heat. Heating,
Preheating or Heat Treatment terminology used in this document is
referred to stress relieving requirements for piping, valves and
vessels before and after welding work. Stress relieving is used to
avert or relieve the detrimental effects of the high temperature
and severe thermal gradients inherent in welding of metals. Arc
Welding: A group of welding processes which produces coalescence by
heating them with an arc or arcs, with or without the application
of pressure and with or without the use of filler metal. Gas
Welding: A group of welding processes wherein a coalescence is
produced by heating with a gas flame or flames, with or without the
application of pressure, and with or without the use of filler
material. Automatic Welding: Welding with equipment which performs
the welding operation without adjustment of the controls by an
operator. The equipment may or may not perform the loading and
unloading of the work. Arc Cutting: A group of cutting processes
wherein the severing or removing of metals is effected by melting
with the heat of an arc between an electrode and the base metal.
(Includes carbon-arc cutting, metal-arc cutting, ga metal-arc
cutting, gas tungsten-arc cutting, plasma-arc cutting, and air
carbon-arc cutting).
Reference: SHE-TSSA-05-2011 / Rev.- 3 Date of Issue: November
2009
Title: Welding, Cutting and Heating Safe Work Practices Next
Review Date: November 2012
Printed Copy Not ControlledKUWAIT NATIONAL PETROLEUM COMPANY
Page 5 of 24
Oxygen Cutting: A group of thermal cutting processes that severs
or removes metal by means of the chemical reaction between oxygen
and the base metal at elevated temperature. The necessary
temperature is maintained by the heat from an arc, an oxyfuel gas
flame, or other source. Oxygen Gouging: Thermal gouging that uses
an oxygen cutting process variation to form a bevel or groove.
Oxygen-Arc Cutting: An oxygen-cutting process that uses an arc
between the work piece and a consumable electrode, through which
oxygen is directed to the work piece. For oxidation-resistant
metals, a chemical flux or metal powder is used to facilitate the
reaction. Soldering: A metal joining process wherein coalescence is
produced by heating to suitable temperatures and by using a
nonferrous alloy fusible at temperatures below 427C (800F) and
having a melting point below that of the base metals being joined.
Bracing: A metal joining process wherein coalescence is produced by
use of a nonferrous filler metal having a melting point above 427C
(800F), but lower than that of the base metals being joined.
Shielded Metal-Arc Welding (SMAW): An arc welding process that
produces coalescence of metals by heating them with an arc between
a covered metal electrode and the work. Shielding is obtained from
decomposition of the electrode covering. Pressure is not used and
filler metal is obtained from the electrode. Gas Tungsten-Arc
Welding (GTAW): An arc-welding process that produces coalescence of
metals by heating them with an arc between a single tungsten
(nonconsumable) electrode and the work. Shielding is obtained from
a gas or gas mixture. Pressure may or may not be used and filler
metal may or may not be used. (This process has sometimes been
called TIG welding). Submerged Arc Welding (SAW): An arc welding
process which produces coalescence of metals by heating them with
an arc or arcs between a bare metal electrode or electrodes and the
work. The arc is shielded by a blanket of granular, fusible
material on the work. Pressure is not used and filler metal is
obtained from the electrode and sometimes from a supplemental
source (welding rod, flux, or metal granules). The terminology
welding works used in this document refers to welding, cutting and
heating activities.
Reference: SHE-TSSA-05-2011 / Rev.- 3 Date of Issue: November
2009
Title: Welding, Cutting and Heating Safe Work Practices Next
Review Date: November 2012
Printed Copy Not ControlledKUWAIT NATIONAL PETROLEUM COMPANY
Page 6 of 24
4.0
HAZARDS, PRECAUTIONS AND SAFE WORK PRACTICES4.1 Welding, Cutting
and Heating Hazards
Welding, cutting and heating (herein after referred to as
"welding work" for simplicity) activities involve many hazards as
follows; 4.1.1 Fire hazard: Open flame, electric arc, molten metal,
sparks or hot surfaces igniting flammable or combustible material.
4.1.2 Burn injuries caused by hot surfaces, sparks, slag or flame.
4.1.3 Health hazards: eye or skin exposure to ultraviolet (UV) and
infrared (IR) radiation; inhalation of dust, toxic fumes such as
oxides of Nitrogen (NOx), Carbon Monoxide (CO), Ozone, etc. and
Oxygen deficiency. 4.1.4 Exposure to ultraviolet rays initially
causes a painful and disabling but temporary form of conjunctivitis
commonly known as "Arc eye". Looking directly into a powerful arc
without eye protection can cause permanent eye damage. Ultraviolet
affects the skin like severe sunburn. 4.1.5 Infrared radiation has
the effect of heating the body tissues on contact. If the intensity
of heat due to infrared is not enough to cause a thermal burn,
there is no further hazard. 4.1.6 Hazards induced from preservative
coatings on metal surface: The toxic hazard will depend on the,
type of electrode used, the base metal being welded or cut, and
whether the base metal is coated with flammable or toxic material
(zinc, lead, paint, etc). 4.1.7 Ultraviolet rays can decompose some
chlorinated hydrocarbon degreasing agents like Trichloroethylene,
even at a considerable distance from the arc, to form highly toxic
substances such as phosgene. 4.1.8 Oxygen Deficiency: In confined
spaces, welding and cutting jobs may lead to oxygen deficient
environment by consuming oxygen or displacing oxygen by inert gas.
4.1.9 Mechanical hazards: unguarded rotating parts, flying
particles, high pressure water in hydrojet cutting, noise. 4.1.10
Compressed gas hazards (refer to relevant controlled SH&E
document on Compressed Gas Cylinders Safe Work Practices)Reference:
SHE-TSSA-05-2011 / Rev.- 3 Date of Issue: November 2009 Title:
Welding, Cutting and Heating Safe Work Practices Next Review Date:
November 2012
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Page 7 of 24
4.1.11 Electric shock (refer to relevant controlled SH&E
document on Electrical Safety) 4.1.12 Explosion Hazard: Welding of
pipeline, vessel and tanks with improper opening and/or vent could
lead to explosion due to heat generation. 4.2 General
Precautions
4.2.1 When practical, objects to be welded, cut or heated shall
be moved to a designated safe location or, if the object cannot be
readily moved, all movable fire hazards in the vicinity shall be
taken to a safe place or otherwise protected (e.g. using flame
retardant barricades, covers, blinding, etc). 4.2.2 If the object
cannot be moved and all the fire hazards cannot be removed,
positive means shall be taken to confine the heat, spark, and slag
to protect the unmovable fire hazard, from these. 4.2.3 The
following welding equipment safety shall be strictly enforced: a)
All welding equipment shall be properly maintained, regularly
inspected by using a checklist (i.e. as per operating procedure),
and shall have valid Safety Certificate. b) Two fire extinguishers
(9 kg. DCP) shall be provided with each welding equipment, one to
be kept at the work and the other at the machine. Plant
extinguishers shall not be used for this purpose c) Welding
equipment shall be parked outside the battery limit whenever
possible and when parked, it should be provided with wheel stoppers
to prevent any movement. d) Location of welding equipment and
laying of cables should not obstruct regular activities. All cables
should be joint-free. e) Earthing should be nearest to the welding
point. It should be through nearby designated pit. In case theres
no earth pit nearby, structures may be used as earthing, but in no
case a product pipeline will be used as earthing. 4.2.4 Welding
work in a Restricted Area shall be done after obtaining a Hot Work
Permit and all requirements pertaining to hot work shall be
enforced such as the Hot Work Risk Assessment for critical welding
jobs in hazardous areas.
Reference: SHE-TSSA-05-2011 / Rev.- 3 Date of Issue: November
2009
Title: Welding, Cutting and Heating Safe Work Practices Next
Review Date: November 2012
Printed Copy Not ControlledKUWAIT NATIONAL PETROLEUM COMPANY
Page 8 of 24
4.2.5 The welder shall not work alone. The welder and helper
must be trained on First-Aid Fire Fighting by KNPC / Contractor
Fire Fighting Trainers. A training card (similar to Fire Watch
card) shall be issued. 4.2.6 When welding work is carried out in a
workshop or any similar location classified as a permit free area,
which is approved by KNPC Safety, a work permit is not required but
the work shall be adequately supervised. The requirement for Fire
Watch shall be mandatory unless exemption is defined from a Risk
Assessment Report. 4.2.7 Degreasing operation and other works using
chlorinated solvents shall be located away from welding work area.
Protective coating other than weldable primers on metal shall be
removed before start of welding or heating. 4.2.8 Welding work on
any tank, vessel or piping shall only be undertaken when it has
been positively isolated from all sources of flammable hazards and
established that it is free of flammable vapors or substances.
(Refer to related procedures and guidelines on Blinding, Work
Permit, Entry, and Gas Test requirements). 4.2.9 While welding on
positively isolated short pipes, wedge opening should be provided
towards the pipe to be welded or nearer to the welding joint.
4.2.10 When cutting a long process pipe, where a gas test cannot be
performed close to the point of cut, a cold cut test hole shall be
drilled from top of pipe and flammable gases tested. If trapped
liquid is suspected, a second hole may be drilled from the bottom.
Similarly, before cutting the bottom plate of a tank, gas test
shall be made through test holes. 4.2.11 Steps shall be taken to
contain and/or quench the sparks. Welded components retain heat for
a period of time after the job is completed. Such components shall
be marked hot and kept cordoned off until sufficiently cooled to
avoid burn injury or fire. 4.2.12 Above or nearby surfaces
contaminated by hydrocarbons or other potential fuels (including
wrapping, coating or other combustible materials) shall be (a)
wiped clean and flushed with water, or (b) steam cleaned, or (c)
covered with clean dirt or sand, or (d) protected by other
precautions which isolate fuel contaminated surfaces from ignition
sources. 4.2.13 Holes in the ground or open sewers or cracks in
pavement should be protected in a manner similar to hydrocarbon
contaminated surfaces by flushing and covering. 4.2.14 All sewers
and catch basins on 15 meters from the work area shall be covered,
plugged, isolated or secured (a) to prevent hydrocarbon vapors from
exiting the sewer or drain and reaching an area of hot work and (b)
to preventReference: SHE-TSSA-05-2011 / Rev.- 3 Date of Issue:
November 2009 Title: Welding, Cutting and Heating Safe Work
Practices Next Review Date: November 2012
Printed Copy Not ControlledKUWAIT NATIONAL PETROLEUM COMPANY
Page 9 of 24
sparks/molten metal from getting into the sewer . A catch basin
equipped with a trap should be flushed continuously with water.
4.2.15 Good housekeeping shall be maintained at work site. The
welding work area shall at all times be kept clean of combustible
and flammable material. Used welding rods, grinding discs, etc.
shall be collected and not thrown around. 4.2.16 Welding works
shall be stopped immediately as and when instructed by the area
custodian of concerned operating personnel or during any other
emergency / MIPP situation. 4.2.17 Every possible precaution should
be taken with jacketed vessels, tanks or containers to vent them
sufficiently before doing any hot work. 4.3 Enclosure of Welding
and Cutting Area
Welding and cutting works at KNPC premises generally require the
protection of equipment and surrounding area from damage or fire
ignition from the hot work activity. This activity includes
oxy-fuel metal cutting, light duty welding, heavy duty welding and
arc gouging. The following requirements shall be strictly enforced:
4.3.1 The welding and cutting area must be totally enclosed, using
a flameproof tarpaulin canvass in a manner to contain sparks,
molten metal/splatters, block the view of the welding/cutting arc
from passerby, and isolate any nearby combustible fuel source from
the hot work activity. 4.3.2 The material of flameproof tarpaulin
canvass shall be made from silica or glass fibers which have low
off gassing and which may melt (but not burn) when contacted by
flames, welding slag or splatter. Refer to Appendix-C for the
guidelines in the selection criteria for flameproof tarpaulin
canvass. 4.3.3 Regular checks shall be carried out (by the Work
Permit Executor) to determine the condition of the flameproof
tarpaulin canvass (e.g. if charred, ripped, torn, melted areas with
holes, etc.). The canvass shall be replaced when the damage is
sufficient enough to potentially exposed equipment surfaces or
whenever molten metal / sparks can not be totally contained. 4.3.4
For heavy and extreme duty operations of arc gouging and flame
cutting in the running process units and piping, sheet metal shall
be placed under the fire stream to lessen the chances of the molten
metal melting through the flameproof tarpaulin canvass. The sheet
metal should be supported 51 mm (2 inches) above the flameproof
tarpaulin canvass. 4.3.5 The tarpaulin canvass enclosure, whenever
required to be air-tight particularly in the running process units
and piping, shall be categorized as aReference: SHE-TSSA-05-2011 /
Rev.- 3 Date of Issue: November 2009 Title: Welding, Cutting and
Heating Safe Work Practices Next Review Date: November 2012
Printed Copy Not ControlledKUWAIT NATIONAL PETROLEUM COMPANY
Page 10 of 24
confined space wherein all terms and conditions related to
Confined Space Entry Safe Work Practices must be applied. 4.4 Fire
Watch Personnel
Work Permit Executor shall provide properly trained and equipped
fire watch personnel for welding and cutting works in running
process units, pipe rack or in any product pipe area. The person
assigned as a fire watch shall have no other duties that would
distract from the primary safety surveillance and response
function. The fire watch person may do other safety-related task if
the primary fire watch responsibility is not compromised. The fire
watch personnel must wear a special vest (orange with FIRE WATCH
print at the back) with their name and employee number written in
the Work Permit. 4.4.1 The fire watch personnel equipment and
knowledge shall include: (a) Understands and capable to recognize
hazards.
(b) Have appropriate functional fire extinguishing equipment
readily available. (c) Trained and certified in the equipments use
and first-aid firefighting. Respective KNPC / Contractors Fire
Fighting Trainers shall train and certify the fire watch.
(d) Familiar with facilities for sounding an alarm in the event
of a fire. (e) Capable to communicate effectively with the
workforce.
4.4.2 The fire watch personnel should understand his duties
which include the following: (a) (b) (c) (d) (e) (f) (g) Shall
continuously monitor and watches for fires in all exposed areas.
Shall remain within 8 meters radius of work vicinity during welding
/ cutting until relieved by another fire watch. Shall maintain
assigned suppression equipment within close proximity Shall be
aware on the location and how to activate the nearest fire alarm.
Shall activate the fire alarm when available equipment is not
sufficient to suppress minor fire. Shall try to extinguish a fire
only when obviously within the capacity of the available equipment.
Shall maintain a watch for at least hour after completion of
welding and cutting works until the area has been inspected and
found to be free of leaks and ignition sources (fires, hot spots or
smoldering materials).Title: Welding, Cutting and Heating Safe Work
Practices Next Review Date: November 2012
Reference: SHE-TSSA-05-2011 / Rev.- 3 Date of Issue: November
2009
Printed Copy Not ControlledKUWAIT NATIONAL PETROLEUM COMPANY
Page 11 of 24
4.5
Personal Protection
The items and requirements included in this document are
described in more detail in other Company SH&E guidelines and
Safe Work Practices such as the Respiratory Protection Program
under Occupational Health, Safety Guidelines for Personal
Protection Equipment, PPE Specifications, etc. 4.5.1 Respiratory
Protection (a) In confined spaces such as tanks, pressure vessel,
large diameter pipelines, confined enclosures, etc., local exhaust
or general ventilation system shall be provided to remove toxic
gases, fumes, etc. and to maintain oxygen concentration above
19.5%. Pure oxygen shall not be used for ventilation. Local exhaust
hoods shall be provided in welding shops or indoor enclosures.
Local exhaust should be achieved by means of movable hood placed as
near as possible to the welding job, and provided with an air flow
rate sufficient to maintain a velocity of 100 fpm (ft./minute) at
the point of welding in the direction of the hood. General
ventilation can be achieved by providing mechanical ventilation at
a minimum rate of 2000 cfm (cu. ft./ minute) of air per welder, or
four air changes per hour, whichever is greater. (c) Where gases,
dust and fumes cannot be maintained below TLV or for any other
reason, welders shall wear canister/cartridge mask suitable for
fumes. In confined spaces where hazard of oxygen deficiency may
exist, airline mask shall be used.
(b)
4.5.2 Eye Protection (a) Goggles or shields fitted with correct
filter lens shall be used during welding and cutting operations to
protect the eyes from light and ultraviolet / infra red radiation.
(see Appendix-A for lens selection). During welding eye protection
shall be used by welder and his helper. Welder's Goggles shall be
used when grinding, chipping, de-slagging and during gas welding
(KNPC Spec PPE/WP/03). Arc welder shall wear welder's shield.
Safety glasses without side shield shall not be worn in any case.
Screens (refer Appendix-C for the Tarpaulin Canvass Cloth Selection
Criteria) shall be provided around welding and cutting jobs to
protect other persons from exposure to direct or reflected
ultraviolet rays.Title: Welding, Cutting and Heating Safe Work
Practices Next Review Date: November 2012
(b) (c)
(d)
Reference: SHE-TSSA-05-2011 / Rev.- 3 Date of Issue: November
2009
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Page 12 of 24
4.5.3 (a)
Protective Clothing and other PPE Fire retardant coveralls (KNPC
spec. PPE/PC/02) and apron (KNPC spec. PPE/WP/05) shall be worn by
welders and fabricators. These protective clothing shall be kept
free of oil and grease and shall have the sleeves and collars kept
buttoned up for protection against ultraviolet and infrared
radiation. Sleeves and collars of coveralls shall be kept buttoned
up for protection against Ultraviolet and Infrared radiation.
Gauntlets or gloves made of leather or flame resistant material
shall be used to protect hands from burns (KNPC spec. PPE/WP/04).
Welders safety boots (KNPC spec. PPE/HP/04) shall be used for
protection against heavy objects and sparks. For overhead work,
caps or shoulder cover and skullcaps made of leather or suitable
flame resistant material shall be used to prevent burn injuries.
During overhead welding, ear protection is recommended against
falling sparks. In plant areas and when the hazard of head injury
exists due to falling objects, etc., Welder's hood (KNPC Spec
PPE/WP/02 - a safety hat fitted with welding mask) shall be
used.
(b) (c) (d) (e)
(f)
5.0
WELDING WORK CLASSIFICATION AND REQUIREMENTS5.1 Gas Welding and
Cutting
5.1.1 Gas welding and cutting operations utilize the heat of the
flame obtained from the combustion of a fuel gas with oxygen.
Oxygen is normally supplied in cylinders containing 244 cu. feet of
oxygen at a pressure of 2200 psig at 70F. Acetylene is supplied in
cylinders and dissolved in acetone over a porous material at a
pressure of 250 psig at 70F. Acetylene cylinders normally contain
300 cu. ft. of acetylene. Acetylene is explosive in a concentration
range of 2% to 82% in air and therefore requires careful handling.
5.1.2 Refer to Compressed Gas Cylinders Safe Work Practices for the
safety precautions related to storage, handling and use of
cylinders and its fittings (regulators, gauges and hoses). 5.1.3
Acetylene gas becomes unstable at pressures above 15 psig and
therefore acetylene regulator pressure shall not be allowed to
exceed 15 psig.Reference: SHE-TSSA-05-2011 / Rev.- 3 Date of Issue:
November 2009 Title: Welding, Cutting and Heating Safe Work
Practices Next Review Date: November 2012
Printed Copy Not ControlledKUWAIT NATIONAL PETROLEUM COMPANY
Page 13 of 24
5.1.4 Acetylene cylinders shall be stored, handled and used in
vertical position to avoid liquid acetone from escaping and
damaging down-stream equipment. If LPG is used as a fuel gas for
cutting purpose, industrial type cylinders shall be used. 5.1.5 All
cylinders shall be kept vertical and secured either in a cylinder
trolley or floor support or lashed to a fixed support. Cylinders
shall not be located in any enclosed space where welding or cutting
job is taking place. Oxygen and acetylene cylinders shall be kept
at least 15 ft. away from the blowtorch or any other source of
ignition. 5.1.6 Flash back arrestors and hose check valves shall be
fitted to both oxygen and fuel gas regulators (see Appendix-B).
5.1.7 Spark lighters shall be used to light torches. Matches and
smoldering rags shall not be used. 5.1.8 Cylinders shall not be
transported with the regulators and hose attached, except on a
purpose made trolley. 5.1.9 Oxygen and acetylene hoses shall be of
different colors or otherwise identified and distinguished from
each other. Maroon is generally used for acetylene and black for
oxygen. 5.1.10 The blowtorch when lighted shall not be placed on or
near cylinders, regulators and hoses. Before changing the torch,
shut-off the gas at the pressure reducing regulators (not by
crimping the hose). 5.1.11 When extinguishing the flame, shut-off
the acetylene first by closing the torch control valve. Only
exception to this is when a backfire occurs in the mixing chamber
where oxygen to be shut off first to stop burning internally.
5.1.12 The blowtorch and hose, when not in use, shall not be left
unattended in any confined space even for short period, e.g., lunch
break. Torch shall be taken out or alternatively, oxygen and
acetylene connections shall be disconnected from the cylinders
located outside confined space. Closing of cylinder valves shall
not be treated as disconnection. 5.1.13 Cylinder valve wrench
should be left in place on the cylinder when in use. 5.2 Electric
Arc Welding and Cutting
5.2.1 Engine of welding machine shall be stopped during
refueling. Guards of rotating parts shall be kept in place. Welding
machine shall be kept 15 meters away from sources of flammable
hazards. Exhaust shall not be allowed to enter confined spaces. It
shall be provided with reflective sticker or warning light if left
by roadside during dark hours.
Reference: SHE-TSSA-05-2011 / Rev.- 3 Date of Issue: November
2009
Title: Welding, Cutting and Heating Safe Work Practices Next
Review Date: November 2012
Printed Copy Not ControlledKUWAIT NATIONAL PETROLEUM COMPANY
Page 14 of 24
5.2.2 All welding leads and returns shall consist of flexible
tough rubber covered cables, robust enough to withstand normal
treatment over rough ground and pedestrian traffic. Where feasible,
cables should be additionally protected by stringing overhead or by
using cable covers. 5.2.3 The insulation of cables, electrode
holders, plugs and sockets shall be regularly inspected for visible
damage and discarded if necessary. If cables are to be joined
together for additional length, proper cable connectors shall be
used ensuring that no live conductor is exposed. 5.2.4 Each welder,
in addition to earth bonding, shall have a separate return lead to
his set. The protective earth connection shall not be used to carry
welding current. The lead shall be connected to the job as near to
the point of welding as possible. It shall not be hooked to other
process lines or structure of pipe rack. 5.2.5 Testing of the
welding rod should be done using a testing plate and not by arcing
on the existing structure or piping. 5.2.6 Welding grounds and
returns shall be securely attached to the work by cable lugs, (or
clamps) in case of stranded conductor or by bolts for strip
conductors. Bolts shall not be used for stranded conductors. 5.2.7
When butt welding of two items is to be done and neither item is
permanently attached to any structure, both items shall be
connected to the welding return. This is necessary to prevent stray
current causing sparks at a distance away from welding point. 5.2.8
Handle of electrode holder shall be made of non flammable
insulating material and be free of joints or holes. A guard disc of
similar material shall be fitted between electrode holder and
handle or similar material covering of electrode holder shall be
provided to prevent live elements from being touched. Electrode
holders shall be suitable to accommodate all sizes of electrodes
and should have an ejector for spent stubs. 5.2.9 Electrode holders
shall not be placed on the ground when not in use, Instead, it
should be hanged or secured to prevent sparking. Cooling hot
electrode holders by dipping in water shall be prohibited. 5.2.10
The cable shall have adequate current carrying capacity to meet the
job requirement. 5.2.11 Welding return lead shall be provided from
the neutral terminal of each phase of an arc welding transformer,
or the negative terminal of a DC Generator to the work piece.
5.2.12 When more than two welders are using the same welding
machine, the polarity of each welding lead and return shall be the
same.Reference: SHE-TSSA-05-2011 / Rev.- 3 Date of Issue: November
2009 Title: Welding, Cutting and Heating Safe Work Practices Next
Review Date: November 2012
Printed Copy Not ControlledKUWAIT NATIONAL PETROLEUM COMPANY
Page 15 of 24
5.2.13 When welding work is not in progress, even for a short
period, the power source of the welding circuit shall be
disconnected. 5.2.14 For all AC welding transformers low voltage
winding shall not be earthed, but the transformer case shall be
effectively bonded to an earthing system adjacent to the equipment.
5.2.15 For all AC driven DC welding generators, no earth connection
shall be applied to either pole of the DC welding output. The
machine frame shall be effectively earthed. 5.2.16 For engine
driven DC welding generators earth connections shall not be applied
to generators output terminals. 5.2.17 In case of gas-shielded arc
welding and when water is used for cooling, the water supply line
shall be equipped with a strainer to keep out impurities which
might get into the torch and plug the water cooling passages.
5.2.18 The power supply plugs, receptacles and extension cords
shall meet standard requirement such as KNPC Intrinsic Safety for
hazardous area locations, GFCI protection, correct polarity, having
approved voltage and ampere ratings that are compatible with their
intended use, protected against physical damage, etc. 5.2.19
Welding transformers shall not be attached to lighting circuits
under any circumstances. 5.3 Other Welding and Cutting
Techniques
5.3.1 Soldering should be done in a well-ventilated areas.
Workers shall wear safety glasses. The major hazards of soldering
are heat, fumes, and the lead content of the solder. The soldering
iron or gun will have a temperature range of 180 340 C (360 to 650
F). This can cause severe localized burns if handled improperly.
The molten metal can also be a potential hazard. The fumes produced
during the soldering process can be a health hazard depending on
what materials caused the fumes. Some materials used as insulation
around conductors, when subjected to high heat, will produce toxic
fumes. When the soldering task has been completed, hands should be
washed thoroughly with soap and water. 5.3.2 Brazing is the process
of joining metals using non-ferrous filler metal such as copper.
Adequate ventilation, goggles and other protective for hot
materials are required. 5.3.3 Thermit(e) Welding is used to attach
electrical cables anodes, etc. This reaction process joins metals
by heating with superheated liquid metal with orReference:
SHE-TSSA-05-2011 / Rev.- 3 Date of Issue: November 2009 Title:
Welding, Cutting and Heating Safe Work Practices Next Review Date:
November 2012
Printed Copy Not ControlledKUWAIT NATIONAL PETROLEUM COMPANY
Page 16 of 24
without pressure. Personnel should wear face shield and other
welder clothing to protect from hot metal particles or sparks.
5.3.4 Plasma Cutting uses a 'plasma' (a gas heated until ionized)
to conduct current. Molten metal is blown away by the hot gas.
Plasma cutting generally requires the precautions similar to Arc
Cutting. The crew shall wear hearing protection. Plasma arc cutting
torches are typically designed with safety interlock systems that
turn off the machine if operators loosen the shield cup or if the
tip touches the electrode inside the nozzle. However, plasma arc
cutting requires higher voltages than welding to start and maintain
the arc, typically 110 to 400 V DC, and touching live electrical
parts can cause fatal shocks or severe burns. Poor connections and
bare spots on cables increase the possibility of electrical shock.
These items shall be inspected daily and replace, not repair, any
worn cables or broken connections. Machine Operators must routinely
inspect for effective ground connections. Connect the frames of all
electrically powered machines to a properly grounded disconnect
switch, receptacle or other appropriate ground. Always double-check
the installation and verify proper grounding. 5.3.5 Hydrojet
Cutting. Personnel shall be protected from direct or indirect hit
by high-pressure water jet. Area around the cutting nozzle shall be
barricaded with metal sheets. Personnel shall wear face shield.
Hoses and couplings shall be checked before each job. Wastewater
contaminated with abrasive metal shall be disposed properly.
6.0
PREHEATING AND HEAT TREATMENT (STRESS RELIEVING)Safe work
practices herein defined shall be cross-referred to terms and
conditions on IC-24 (Inspection and Corrosion Procedure for Stress
Relieving). Preheating and Heat Treatment requirements for piping,
valves and vessels before and after welding are used to avert or
relieve the detrimental effects of the high temperature and severe
thermal gradients inherent in welding of metals. Precautionary
measures on possible electric shock, moving parts, and hot parts
hazards shall be appropriately addressed, which include but not
limited to the following: 6.1 Electric Shock Hazard Precautions
Touching live electrical parts can cause fatal shocks or severe
burns. The power circuit and output bus bars or connections are
electrically live whenever the output
Reference: SHE-TSSA-05-2011 / Rev.- 3 Date of Issue: November
2009
Title: Welding, Cutting and Heating Safe Work Practices Next
Review Date: November 2012
Printed Copy Not ControlledKUWAIT NATIONAL PETROLEUM COMPANY
Page 17 of 24
is on. The input power circuit and machine internal circuits are
also live when power is on. The machine should be correctly
installed or properly grounded. 6.1.1 All connecting bus bars and
coolant fittings should be enclosed to prevent unintentional
contact. 6.1.2 Dry, hole-free insulating gloves and body protection
shall be worn. 6.1.3 Employee shall be insulated from work and
ground by the use of dry insulating mats or covers big enough to
prevent any physical contact with the work or ground. 6.1.4
Nonconductive coolant hoses with a minimum length of 457 mm (18
inches) to provide isolation shall be used. 6.1.5 Equipment shall
be properly installed and grounded. Equipment operator shall always
verify the supply ground and ensure that input power cord ground
wire is properly connected to ground terminal in disconnect box or
that cord plug is connected to a properly grounded receptacle
outlet. 6.1.6 All panels and covers shall be securely kept in
place. 6.2 Fire or Explosion Hazard Precautions
6.2.1 The unit shall not be operated in explosive atmosphere
6.2.3 The unit shall not be installed near flammables. All
flammable materials shall be kept away (15 meters) from work area.
6.2.4 The unit shall not be located on, over, or near combustible
surfaces. 6.2.5 Fire Watch shall be assigned along with a standby
fire extinguisher 6.3 Fumes and Gases Hazard Precautions
6.3.1 Heating of certain materials, adhesives, and fluxes can
produce hazardous fumes and gases. Appropriate respiratory
protections should be used. Always refer to Material Safety Data
Sheet (MSDS) and the manufacturers instruction for adhesives,
fluxes, metals, consumables, coatings, cleaners, and degreasers.
6.3.2 Heating shall not be permitted near degreasing, cleaning, or
spraying operations. The heat can react with vapors to form highly
toxic and irritating gases. 6.3.3 During heat treatment work in a
confined space, fumes and gases from heating can displace air and
lower the oxygen level causing injury or death. Safe work practices
for confined space entry shall be followed with continuous gas
monitoring.
Reference: SHE-TSSA-05-2011 / Rev.- 3 Date of Issue: November
2009
Title: Welding, Cutting and Heating Safe Work Practices Next
Review Date: November 2012
Printed Copy Not ControlledKUWAIT NATIONAL PETROLEUM COMPANY
Page 18 of 24
6.3.4 Coated metals should not be overheated, such as the
galvanized, lead or cadmium plated steel, unless the coating is
removed from the heated area, the area is well ventilated, and if
necessary, while wearing an air-supplied respirator. The coatings
and any metals containing these elements can give off toxic fumes
if overheated. Whenever required, refer to relevant coating MSDS
for temperature information.
7.0
HOT TAPPING AND WELDING ON LIVE PIPING & EQUIPMENTIn certain
circumstances, welding is allowed on live lines and tanks due to
difficulty in depressurizing and getting freed of flammable
material. Welding work on live pipelines and equipment includes
welding of stubs on lines or vessels prior to drilling for hot tap,
welding brackets on tanks, patchwork and box welding. Such work
requires extra precautions in addition to normal hot work
precautions. Risk assessment shall be carried out for all hot
tapping and welding on live piping and equipment. Inspection
Procedure IC-18: "Hot Tapping & Welding on Equipment and
Piping" Procedures and requirements shall be strictly enforced. Hot
tapping shall be considered as a last resort and every effort shall
be made to weld the tie-ins during shutdown. Immediately prior to
commencement of welding on live equipment, the issuing authority
shall ensure that safe conditions for carrying out the job have
been established. Hot tapping and/or Welding Authorizations (as per
IC-18) shall be available with the permit. Issuing authority shall
himself be present at the start of the job and thereafter keep in
close touch at frequent intervals. Executing authority shall
continuously supervise the job.
8.0
TIE-IN ON HYDROCARBON CONTAMINATED LINESA tie-in on hydrocarbon
contaminated line involves the hazard of hot work on lines which
have been taken out of service but cannot be entirely freed of gas
or oil. This type of work includes work on flare lines or long,
large diameter lines which cannot be easily cleaned. This work is
normally carried out on open-ended lines, which will need to be
blinded and possibly plugged by means of an expanding plug to
isolate a small portion of the line near the point where the hot
work is to be done. A plug should be fixed at a minimum distance of
meter from the point of hot work and should be of an expanding type
so as to make a tight seal. If possible the space above the plug
should be filled with water before welding. The space behind the
plug shall be vented to a safe location to avoid a pressure
build-up.
Reference: SHE-TSSA-05-2011 / Rev.- 3 Date of Issue: November
2009
Title: Welding, Cutting and Heating Safe Work Practices Next
Review Date: November 2012
Printed Copy Not ControlledKUWAIT NATIONAL PETROLEUM COMPANY
Page 19 of 24
Other normal welding precautions for hazardous area, as
described in previous sections, shall be followed.
9.0
AUDIT REQUIREMENTSCompliance on the complete implementation of
this guideline shall be regularly audited through the existing
audit and inspection programs such as in the Safety Performance
Audit and Work Permit Compliance Audit that is being carried out by
the management team and Safety Section.
Reference: SHE-TSSA-05-2011 / Rev.- 3 Date of Issue: November
2009
Title: Welding, Cutting and Heating Safe Work Practices Next
Review Date: November 2012
Printed Copy Not ControlledKUWAIT NATIONAL PETROLEUM COMPANY
Page 20 of 24
APPENDIX-A GUIDE FOR SELECTION OF LENS SHADESHADE NUMBERS ARE
GIVEN AS A GUIDE ONLY AND MAY BE VARIED TO SUIT INDIVIDUAL NEEDS
PROCESS Shielded (SMAW) Metal Arc Welding ELECTRODE SIZE inches
(mm.) Less than 3/32 (2.4) 3/32-5/32 (2.4-4.0) 5/32-1/4 (4.0-6.4)
More than (6.4) ARC CURRENT (Amperes) Less than 60 60-160 160-250
250-550 Less than 60 60-160 160-250 250-500 Less than 50 50-150
150-500 (Light) (Heavy) Less than 500 500-1000 Less than 20 20-100
100-400 400-800 Less than 20 20-40 40-60 60-80 80-300 300-400
400-800 PLATE THICKNESS inches mm Oxyfuel Gas Welding (OFW) Light
Medium Heavy Oxygen Cutting (OC) Light Medium Heavy Under 1/8 1/8
to Over 1/2 Under 1 1 to 6 Over 6 Under 3 3 to 13 Over 13 Under 25
25 to 150 Over 150 Minimum Protective Shades 7 8 10 11 7 10 10 10 8
8 10 10 11 6 8 10 11 4 5 6 8 8 9 10 * Suggested Shade No. (Comfort)
10 12 14 11 12 14 10 12 14 12 14 6 to 8 10 12 14 4 5 6 8 9 12 14 3
or 4 2 14 * Suggested Shane No. (Comfort) 4 0r 5 5 or 6 6 or 8 3 or
4 4 or 5 5 or 6
Gas Metal Arc Welding (GMAW) and Flux Cored Arc Welding (FCAW)
Gas Tungsten (GTAW) Arc Welding
Air Carbon Arc Cutting (CAC-A) Plasma Arc Welding (PAW)
Plasma Arc Cutting (PAC)
Torch Brazing (TB) Torch Soldering (TS) Carbon Arc Welding
(CAW)
* As a rule of thumb, start with a shade that is too dark to see
the weld zone. Then go for a lighter shade which gives sufficient
view of the weld zone without going below the minimum. In oxyfuel
gas welding or cutting where the torch produces a high yellow
light, it is desirable to use a filter lens that absorbs the yellow
or sodium line in the visible light of the (spectrum) operation.
Reference: SHE-TSSA-05-2011 / Rev.- 3 Date of Issue: November 2009
Title: Welding, Cutting and Heating Safe Work Practices Next Review
Date: November 2012
Printed Copy Not ControlledKUWAIT NATIONAL PETROLEUM COMPANY
Page 21 of 24
APPENDIX-B: FLASH BACK ARRESTORS AND HOSE CHECK VALVES
Acetylene (Maroon Color Cylinder)
Oxygen (Black Color Cylinder)
Gas welding equipment showing positions of flashback arrestors
and hose check valves
1 Normal gas flow from regulator 2 To hose and blowpipe 3
Back-fed gas 4 Two-way cut-off halts flow in both directions and
remains closed even if pressure increases 5 Cut-off opens lever
revealing red indicator 6 Pressure relief valve allows gases to
escape 7 Sintered metal flame trap
Normal Flow
Back Pressure
Operation of Flash Back Arrestor
Reference: SHE-TSSA-05-2011 / Rev.- 3 Date of Issue: November
2009
Title: Welding, Cutting and Heating Safe Work Practices Next
Review Date: November 2012
Printed Copy Not ControlledKUWAIT NATIONAL PETROLEUM COMPANY
Page 22 of 24
TARPAULIN CANVASS CLOTH SELECTION CRITERIAThis reference
provides generic guidelines on the cloth selection and typical
applications of flameproof tarpaulin canvass that is generally
required in the protection of equipment and surrounding area from
damage or fire ignition from the hot work activities. C.1 Tarpaulin
Canvass Cloth
APPENDIX - C
Basically, there are two classes of cloths used for welding fire
protection today. One is glass fiber based (fiberglass) , the other
is silica fiber based. The difference between the two is
temperature rating. Fiberglass is rated at 538 C (1000 F) whilst
silica is rated at 982 1093 C (1800 2000 F), plus a 538 C (3000 F)
melting temperature. Coatings are used to enhance the cloths duty
performance or its resistance to moisture. Some coatings such as
neoprene will burn and give off fumes (off gassing). It is usually
best to not use coated materials as the coatings can also char
making the cloth brittle to handle and create air-borne fibers. All
cloths will become brittle to handle given enough exposure to heat.
As the cloth can be woven into different weave patterns and use
different size strands, the cloth can highly varied in thickness or
closeness of weave pattern. The thickness and how tightly the cloth
is woven affects its performance to resist tearing., abrasion,
molten metal sprays and droppings, or thermal protection from
radiant energy of the welding arc or torch. Typical cloth thickness
ranges from 0.017 inch to 0.6 inch and can be supplied in roll or
blanket or canvass forms. Blankets / canvass are cut to size from
rolls and may be hemmed and grommets installed for hanging the
blankets / canvass. Rolls are typically 40 inches to 60 inches wide
(some can be 120 inches) by 50 yards in length. Thickness and
weight give an indication of robustness, but are not the only
factors in choosing the correct cloth for the application. Some
cloths abrade easily, others do not. The coated products do better
than the non-coated under abrading conditions such as heavy traffic
floors or scaffolding. Coated products can be used to protect
vertical surfaces where any weld splatter will tend to bounce off.
Vermiculate is used in the coating to raise the temperature rating
of fiberglass cloths. Neoprene and silicone rubber coatings impart
strength and stiffness as well as capturing the fibers when cut or
abraded. Some cloths are very slick and can cause a slipping
hazard. Other cloths are easily cut when placed over sharp metal
edges. The many grades of cloth are manufactured by several textile
mills around the world. The cloth is usually sold by distributor
under brand names rather than mill identification and product
number. The same mill product may have several different brand
names, making it difficult to specify for purchase. It is best to
examine and test the cloth beforeReference: SHE-TSSA-05-2011 /
Rev.- 3 Date of Issue: November 2009 Title: Welding, Cutting and
Heating Safe Work Practices Next Review Date: November 2012
Printed Copy Not ControlledKUWAIT NATIONAL PETROLEUM COMPANY
Page 23 of 24
purchasing to assure good performance in practice. Testing can
be as simple as exposing the cloth to an open flame to see if it
will burn. Other tests can be arc gouging steel and directing the
molten metal at the cloth in the position the cloth will be used
(e.g. down flat, vertical, etc.). C-2 Tarpaulin Canvass Cloth
Selection Criteria Per ApplicationMINIMUM THICKNESS MINIMUM
LAYERS
DUTY
DUTY DESCRIPTION
CLOTH TYPE
Light
GTAW, GMAW, FCAW and SMAW welding at 150 amps or less. Light
grinding to remove weld crown or defects. No arc gouging or flame
cutting. No open flame preheating. SMAW, GMAW and FCAW welding at
more than 150 to 250 amps. Light grinding to remove weld crown or
defects. No arc gouging or flame cutting. No open flame preheating.
GMAW, FCAW and SMAW welding in excess of 250 amps. Heavy grinding
to remove weld crown or defects. Light limited arc gouging. Molten
metal spray directed away from the tarpaulin canvass cloth unless
two (2) layers are used. Limited flame cutting with molten metal
and hot parts restricted to falling on steel sheet to protect the
cloth from seeing high temperatures. No open flame preheating. Arc
gouging or flame cutting such that molten metal will fall or be
blown onto the cloth. Heavy grinding to remove dross or to cut
through existing piping or structural. Open flame preheating such
that the flames could contact the cloth or be exposed to the heat
for long periods.
Fiberglass (Non-coated)
0.03 inch
1
Medium
Fiberglass (Non-coated)
0.03 inch
1 for vertical surfaces 2 for surfaces flat
Heavy
Silica
0.03 inch
1 for vertical surfaces 2 for surfaces flat
Extreme
Silica
0.05 inch
1 for vertical surfaces 2 for surfaces flat
Reference: SHE-TSSA-05-2011 / Rev.- 3 Date of Issue: November
2009
Title: Welding, Cutting and Heating Safe Work Practices Next
Review Date: November 2012
Printed Copy Not ControlledKUWAIT NATIONAL PETROLEUM COMPANY
Page 24 of 24
Notations: (a) It is preferable that two (2) layers should be
used at 90 degrees to each other with 2 inches minimum laps to
lessen the chances of the laps opening up during welding, grinding
or cutting operations which will subsequently expose the equipment
surfaces or a means for molten metal or sparks escaping out of the
work enclosure. Several layers of thinner material can be used in
lieu of one minimum thickness cloth. Top layers shall be monitored
closely for replacement, especially those applied to flat surfaces
which see a lot of splatter or falling slag. For the heavy and
extreme duty operations of arc gouging and flame cutting, sheet
metal shall be placed under the fire stream to lessen the chances
of the molten metal melting through the multi-layer tarpaulin
canvass thickness. The sheet metal shall be supported about 2
inches above the tarpaulin canvass. Once the tarpaulin canvass has
been installed, regular checks shall be made to determine its
condition (charred, ripped, torn, melted areas with holes, etc.).
Replace the tarpaulin canvass when the damage is sufficient enough
to potentially expose equipment surfaces or when molten metal or
sparks can not be totally contained.
(b) (c) (d)
(e)
Reference: SHE-TSSA-05-2011 / Rev.- 3 Date of Issue: November
2009
Title: Welding, Cutting and Heating Safe Work Practices Next
Review Date: November 2012