Engineering Procedure - baixardoc

Previous Issue: 23 August 2011 Next Planned Update: 23 August 2016

Revised paragraphs are indicated in the right margin Page 1 of 54

Primary contact: Anezi, Mohammed Ali on +966-13-8809528

Copyright©Saudi Aramco 2013. All rights reserved.

Engineering Procedure

SAEP-1662 28 October 2013

Cleaning of Heat Exchangers and Unfired Plant Equipment

Document Responsibility: Materials and Corrosion Control Standards Committee

Saudi Aramco DeskTop Standards

Table of Contents

1 Scope.................................................................... 2 2 References............................................................ 2 3 Purpose................................................................. 2 4 Responsibilities..................................................... 3 5 Introduction to Cleaning........................................ 5 6 Preparations for Chemical Cleaning..................... 5 7 Criteria For Cleaning............................................. 9 8 Chemical Cleaning Treatment Selection............... 9 9 Alkaline Treatments............................................ 13 10 Acid Cleaning and Neutralization........................ 19 11 Passivation.......................................................... 30 12 Evaluating Cleaning Performance by Inspection... 31 13 Equipment Lay-Up.............................................. 31

Appendix 1 – Definition of Terms..................................... 31 Appendix 2 – Contractor Submittals................................. 32 Appendix 3 – List of Approved Inhibitors and Manufacturers.................................. 34 Appendix 4 – Chemical Cleaning Log Sheet.................... 35 Appendix 5 – High Pressure Water Jetting (HPJ)……..... 36 Appendix 6 – Onstream Cleaning of Heat Exchangers… 38 Appendix 7 – Cleaning of Twisted Tube Heat Exchangers.............................. 43 Appendix 8 – Heat Transfer Coefficients and Fouling Factor.................................. 45 Appendix 9 – Economic Evaluation TFRE Concept............ 47 Appendix 10 – Safety Hazards with Chemical Cleaning….. 50 Appendix 11 – Cleaning Chemical Compatibility Chart for Materials................................ 54

Document Responsibility: Materials and Corrosion Control Standards Committee SAEP-1662

Issue Date: 28 October 2013

Next Planned Update: 23 August 2016 Cleaning of Heat Exchangers and Unfired Plant Equipment

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1 Scope

This procedure defines the responsibilities of the various departments involved in the

pre commission and operational cleaning. It outlines methods to determine the need for

cleaning, the criteria for selecting specific cleaning procedures, and steps involved in

various cleaning procedure alternatives.

The use of high pressure water jetting is covered in Appendix 5 and on-stream cleaning

in Appendix 6. Advice is available from Materials Engineering & Corrosion

Operations Division /Consulting Services Department (ME&COD/CSD) to draft

detailed procedures for cleaning specific equipment.

The procedures listed herein are applicable to clean undesirable deposits in heat

exchangers and other unfired plant equipment such as piping, columns, vessels,

Multiple Effect Distillation (MED) units, etc.

For twisted tube heat exchangers, see Appendix 7.

For evaluation and recommendation of alternative cleaning procedures not listed herein

contact ME&COD/CSD.

2 References

The following documents apply as referenced in this procedure.

Saudi Aramco Engineering Procedure

SAEP-327 Disposal of Wastewater from Cleaning, Flushing,

and Dewatering Pipelines and Vessels

Saudi Aramco Engineering Standard

SAES-B-069 Emergency Eyewashes and Showers

Saudi Aramco Manual

SAER-2365 Saudi Aramco Mothball Manual

3 Purpose

It is necessary to clean a new equipment initially and periodically thereafter for its

efficient operation, corrosion control and prevention of fouling related failures.

This scope includes, but not limited to, coolers and condensers, DEA, MEA, MDEA,

DGA and any other amine systems, TEG, refrigerant systems, vessels, columns, towers,

storage tanks, and piping. Cleaning is accomplished by a combination of (not

necessarily in the sequence listed):

http://standards/docs/SAEP/PDF/SAEP-327.pdf

http://standards/docs/SAES/PDF/SAES-B-069.pdf

https://standards.aramco.com.sa:10009/docs/Engineering_Reports/PDF/SAER-2365.pdf




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Mechanical cleaning

High pressure water jetting (HPJ)

Hot alkaline treatment

Acid cleaning and Neutralization

Passivation

Cleaning with Solvents

For some equipment it may not be necessary to use all of the above steps since the degree

of contamination will vary from unit to unit. Scale severity, and its analysis, tube failures,

inspection and consultation with the various departments outlined in Section 4 will

determine the exact procedure to be used. This procedure does not override an equipment

manufacturer's cleaning recommendations, especially where warranty rights are involved.

Differences shall be questioned and resolved by the proponent.

4 Responsibilities

4.1 The Project Construction Agency is responsible for cleaning new equipment.

4.2 The Facility Operating Department is responsible for cleaning commissioned

equipment.

4.2.1 Maintenance

Prepares the equipment mechanically.

Provides maintenance support during the cleaning operation.

Coordinates cleaning and obtains approved contractor services.

Commentary:

Contact ME&COD/CSD for Saudi Aramco’s approved list of chemical cleaning contractors.

4.2.2 Operations Engineering

Prepares necessary operation procedures, advises the foreman of the

plant during the chemical cleaning of the equipment.

Acts as a technical representative to facility operator during the

chemical cleaning.

Ensures adequate safety procedures and precautions are taken.

Notifies Loss Prevention Department to review safety during

cleaning.




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Coordinates and obtains the approval of chemical cleaning

procedures and formulations from the ME&COD/CSD and the

Research and Development Center (R&DC).

Requests the presence of specialist personnel from ME&COD/CSD

if this service is desired.

4.2.3 Operations Inspection

Has the responsibility for inspection before and after cleaning.

Is responsible to get and keep the corrosion monitoring records from

the contractor.

Maintains history of equipment chemical cleaning. Incorporates

relevant reports and data into permanent plant records.

4.3 Loss Prevention Department

Audits cleaning operations and permits

Advises on field safety precautions on request.

4.4 Research and Development Center (R&DC)

Evaluates new chemical cleaning products and new corrosion inhibitors.

Provides specialist/consultant advice on request.

4.5 Regional Laboratories

Perform scale density, solubility, and chemical analysis, inhibitor

effectiveness testing and analyses during actual cleaning operations on

request.

Verify the purity of acids and chemicals used for chemical cleaning on

request.

4.6 Chemical Cleaning Contractor

The chemical cleaning contractor is selected from the Consulting Service

Department's approved list of chemical cleaning contractors. Contractor

responsibilities are stated in the contract. Usually this includes: submittal of

procedures and documents per Appendix 2; supply of all chemicals, inhibitors

per Appendix 3, auxiliary pumping and heating equipment as required, and the

necessary personnel for chemical cleaning, including a qualified chemist for

chemical analysis during the chemical cleaning; on line monitoring and control

of corrosion rates; disposal of all waste water and chemical solutions as




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provided in SAEP-327; and cleaning the equipment to meet or exceed the

acceptance criteria outlined in Section 12.

4.7 ME&COD/CSD

Reviews and approves the cleaning procedures and subsequent changes

necessitated by the field conditions.

Provides specialist/consultant advice on request.

Witnesses the cleaning operation on request.

5 Introduction to Cleaning

The cleaning process may involve a combination of several stages. Plan the stages of

cleaning in advance.

5.1 Mechanically remove, using power brushes or reamers as much of the deposits

as possible from the equipment.

5.2 Remove deposits if access is available with high-pressure water jetting.

See Appendix 5 for details.

5.3 Clean on-stream with acid slugging. See Appendix 6.

5.4 Remove oil, grease, and organic deposits and to neutralize pyrophoric material

with hot permanganate, alkaline treatment, or surfactants.

5.5 Removal of tarry and polymerized deposits by cleaning with organic solvents

such as heavy aromatic naphtha (HAN), kerosene, diesel, gas oil, or proprietary

solvents.

5.6 Acid clean to chemically remove, mill scale, mineral deposits from water,

process side deposits and corrosion products.

5.7 Neutralize acids and passivate to form a strongly adherent protective oxide layer

on the wetted metal surface.

6 Preparations for Chemical Cleaning

6.1 General

1. Install all necessary temporary piping, sacrificial valves and pressure,

temperature and level instruments. Do not connect equipment with

dissimilar metals into one system for circulation of acids.

2. Isolate the equipment from the process side by blinds. Install vents and





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adequately sized temporary valves to permit draining acids within

30 minutes. Use temporary plugs or slip blinds to isolate sections that do

not require cleaning.

3. Store all chemicals needed for the procedure on-site prior to commencing

cleaning, including emergency neutralizing agents and nitrogen as well as

wet lay-up chemicals.

4. Ensure that an adequate supply of water is available for flushing and

cleaning.

5. Ensure that instrument connections (except those temporarily installed) are

disconnected before acid cleaning stage.

6. Install fittings for liquid sampling, flow elements, temperature probes, pipe

spools with on-line access fittings for corrosion monitoring probes.

7. Provide adequate lighting at all operating points.

8. Plan for the disposal of wastewater and spent chemical solutions per

SAEP-327.

9. Perform checks on valve lineups as required for flushing and reversing

circulation.

10. Notify ME&COD/CSD and the Regional Laboratories of intention to

chemically clean. Request the presence of ME&COD/CSD personnel

during any stage of chemical cleaning for consultations as necessary.

11. Ensure utility water is available, or provide a temporary supply

connection.

12. Ensure sufficient supply of nitrogen at 80 psig to quickly drain using

nitrogen pressure any acid in the equipment.

13. Check and ensure that the flow design includes: flow reversal manifold

and valves, control valves and bypass to control circulation within

specified limits, blend filling of corrosive chemicals (acids and chelants)

without exposure to the atmosphere.

14. Test the cleaning circuit hydrostatically at 1.25 times the dead head

discharge pressure of the circulating pump, after installation of all

temporary piping and connections, prior to chemical cleaning.

15. Ensure that an external heat source is available to maintain the cleaning

fluid temperature, within the limits specified.

16. Ensure spare pumps are available in case of a pump failure to maintain





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circulation, and nitrogen pressure connection to drain the acid within

fifteen minutes in case of an emergency. Ensure sufficient holding tank

capacity is available for draining and neutralizing cleaning solutions if

necessary.

17. Ensure, using standard samples, that on-site chemical analytical

procedures and laboratory analytical procedures yield results within ±10%.

18. Ensure inhibitor is selected from Appendix 3.

19. Determine the volume of the equipment by filling with water and draining

it through a flow meter.

20. Be aware of the safety hazards (see Appendix 10) associated with chemical

cleaning and take adequate safety measures.

21. Ensure chemical feed lines are a minimum of 1/12th

the diameter of the

vessel or exchanger; drains and vents are clear.

22. Ensure that the chemical cleaning contractor is on-site with mixing tanks,

chemicals, flow meter, corrosion monitoring equipment, pH and

temperature probes, and pumping equipment to blend fill and circulate

chemicals.

23. Flush the equipment with water until it runs clear to remove all loose and

soluble deposits.

24. Use commercial grade quality for all chemicals except where austenitic

materials are present in the equipment to be cleaned. In this case, the total

chlorides of all the chemicals in the mixture must not yield a final solution

containing greater than 50 mg/L as chloride.

25. Install at least one corrosion probe in the circulating loop for on line

monitoring and control of corrosion rates.

6.2 Cleaning Record

1. Cleaning temperatures, time, dates of cleaning process, chemical additions,

and results of chemical cleaning analysis are recorded in a logbook by

Operations Engineering.

2. Typical log sheets include what is shown in Appendix 4, contractor's log

sheets and the on line corrosion monitoring results.

3. Operations Inspection Unit is to collect and keep as permanent plant

records, these log sheets on completion of the cleaning operation.




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6.3 Safety Precautions

1. Close all instrument connections and disconnect to protect instruments

from exposure to corrosive solutions.

2. Keep operational and tested, permanent or temporary eye wash fountains

and safety showers per SAES-B-069, within 15 meters and accessible in

10 to 15 seconds of the work site, prior to initiation of chemical cleaning.

3. Adhere to the work permit procedures. Vent flammable gases when

corrosive chemicals are used in the cleaning operation. A “Release of

Flammable Gas” Work Permit will be required. Therefore, do not permit

welding, burning, or running of welding machines or generator sets within

a 5 meter radius from the vents of the systems being cleaned. A hot work

permit will be required to operate pumps. Nitrogen is a non-toxic gas that

will not support life. Entrance by personnel into the equipment will be in

accordance with the requirements in the CONFINED SPACE ENTRY

permit procedures including oxygen tests, combustible gas tests, use of

lifelines if required, etc.

4. Keep hoses connected to an operable water supply adjacent to the

equipment being cleaned to dilute any chemical spills.

5. Rope off the area where the blending and heating of chemical solutions is

performed and post “DANGER” signs. Do not let unauthorized personnel

enter the roped off area.

6. Keep at cleaning site chemical hazard bulletins on various chemicals or

materials from the Environmental Protection Department. These bulletins

provide information on storage, handling, and protective measures for

these chemicals.

7. Ensure all nitrogen cylinders if in use, have individual regulators and are

adequately secured. Also, ensure the nitrogen manifold has a safety relief

valve attached.

8. Ensure all personnel handling chemicals wear protection equipment

required by the chemical hazard bulletins of the materials involved.

9. Ensure the contractor is equipped with adequate portable fire extinguishers

for its equipment.

10. Be aware and prepared for safety hazards with equipment deposits, noted

in Appendix 10.

http://standards/docs/SAES/PDF/SAES-B-069.pdf




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7 Criteria for Cleaning

Use any one of the following criteria to determine when to schedule cleaning.

1. Inspection: On every T & I, check inside the tubes and shell for corrosion and

scale. Note down the location and amount of scale buildup and check tube ends

for pits, and deposit. Scrape off deposits to determine its composition. Low flow

rate areas, boots, drains are particularly susceptible to heavy deposit buildup.

Visual inspection will indicate the condition of the equipment and will be one of

the primary factors in determining the need for cleaning. Inspect tubes inside and

on shell side for total blockage. Blocked tubes cannot be chemically cleaned until

a flow path is made for chemical circulation.

2. Clean whenever the actual heat transfer coefficient (Uactual) drops to 60% of the

Udesign at heat exchanger design operating conditions. (See Appendix 8).

3. Clean when the ten-day average Rf reaches twice of Rfdesign value. Rf is

independent of the fluctuations in the flow rates during the service period.

(See Appendix 8).

4. Clean when the total fouling related expenditure (TFRE) is at the minimum.

(See Appendix 9).

5. Clean whenever the drop in heat duty is unacceptable to Plant Operations.

6. Clean during T&I or unplanned shutdown to take advantage of down time.

7. Using scale monitoring or based on recorded rate of scale or corrosion products

build up, schedule cleaning before fluid flow is obstructed inside or outside the

tubes.

8 Chemical Cleaning Treatment Selection

8.1 General Criteria

8.1.1 Primarily select chemicals that: a) are safe to use, b) are compatible with

the materials of construction (see Appendix 11), c) will remove > 70% of

the undesired deposits, d) will achieve the desired degree cleaning.

8.1.2 With these criteria satisfied, make the final selection, with due reference

to other constraints including cost, environmental restriction on disposal

of waste solutions, and cleaning time available. Responsibility for the

final procedure of the treatment(s) is defined in Section 4. For on stream

cleaning see Appendix 6. Off stream chemical cleaning will involve one

or more of the following steps: Hot alkaline degreasing (see Section 9),

acid cleaning (see Section 10), followed by neutralization and




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passivation treatment (see Section 11). Laboratory analyses of deposit

samples will determine the above sequence.

8.1.3 High pressure water jetting (HPJ) may precede or follow to remove

loosened scale (see Appendix 5). HPJ is very effective to remove most

brittle deposits. The use of HPJ is recommended alone, or before

chemical cleaning.

8.2 Analysis of Scale

8.2.1 General - Fouling composition, quantity, and distribution, will vary

considerably between one equipment and another, or even within the

same equipment at various time intervals during its life. It is therefore

necessary in each case, to select a specific treatment, or series of

treatments, which will be most effective in achieving thorough and safe

cleaning, to restore its operational efficiency. Determine the

composition of the scale or deposit and the suitable acids or organic

solvents to remove them before any chemical cleaning. Take a sample

or samples carefully representative of the deposit.

8.2.2 Solubility in Dilute HCl - This figure represents the weight percent of the

deposit, which will dissolve in boiling 7.5% wt., inhibited hydrochloric

acid.

8.2.3 Loss on Ignition - This figure represents the weight percentage of the

deposit that can be removed by heating the insoluble residue from 8.2.1

above to 315°C in a laboratory furnace. The result is indicative of the

organic content of the deposit in the forms of oil, grease, degraded

polymers and carbon. If the figure is high (greater than 10%) further

definition of the organic content can be determined by refluxing the

sample with a suitable organic solvent, which will indicate the relative

proportions of oil and grease, and carbon. These proportions assist in the

selection of a suitable hot alkaline or permanganate treatment.

8.2.4 Insoluble Residue - This figure represents the insoluble complexes of

other cations and, if the quantity is significant (i.e., greater than 2%)

further treatments with more concentrated hydrochloric acid may be

required to render the material soluble.

8.2.5 Metals - The metal ions present in the deposit, are analyzed for iron (Fe),

copper (Cu), calcium (Ca), magnesium (Mg), nickel (Ni), zinc (Zn),

manganese (Mn) and sodium (Na). These results are useful to determine

the number of cleaning stages that are likely to remove all the deposits

from the system.

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