32-SAIP-11

Inspection Procedure 32-SAIP-11

18 April 2009

Inspection of Air-Cooled Heat Exchangers Document Responsibility: Inspection Engineering Standards Committee

Saudi Aramco DeskTop Standards Table of Contents 1 2 3 4 5 6

Scope............................................................. 2 Purpose.......................................................... 2 References..................................................... 2 Definitions...................................................... 3 Responsibilities of Inspector.......................... 4 Corrosion Rates, Remaining Life and Inspection Interval.................................. 7 7 Recommendation for Repairs....................... 7 8 Alterations and Additions............................... 7 9 Rerating Because of Operating Changes In Temperature or Maximum Allowable Working Pressure (MAWP).................... 8 10 Records......................................................... 8 11 Safety............................................................ 8

Previous Issue: 31 August 2004 Next Planned Update: 18 April 2014 Page 1 of 8 Primary contact: Kakpovbia, Anthony E. on 966-3-8747226 Copyright©Saudi Aramco 2009. All rights reserved.

Document Responsibility: Inspection Engineering Standards Committee 32-SAIP-11 Issue Date: 18 April 2009 Next Planned Update: 18 April 2014 Inspection of Air-Cooled Heat Exchangers

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Scope 1.1

This SAIP describes the responsibilities of inspector and inspection procedures to be followed by the engineering inspection units and shop inspecting aircooled heat exchanger equipment (Fin-Fan Coolers).

1.2

This SAIP is intended to establish a standardized methodology by Saudi Aramco inspection personnel in the implementation of inspection programs within Saudi Aramco facilities. The SAIP shall not be included in purchase order or contract documents issued to outside agencies.

Purpose This SAIP provides a summary of Inspection activities for inspection of air-cooled heat exchangers. It specifies inspection techniques to be used on heat exchanger components, and defines inspector responsibility in repairing, altering, testing, and maintaining records on heat exchangers.

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References 3.1

Saudi Aramco References Saudi Aramco Engineering Procedure SAEP-20

Equipment Inspection Schedule

Saudi Aramco Engineering Standards SAES-A-004

General Requirements for Pressure Testing

SAES-A-005

Safety Instruction Sheet

SAES-A-007

Hydrostatic Testing Fluids and Lay-Up Procedures

Saudi Aramco Materials System Specification 32-SAMSS-011

Air Cooled Heat Exchangers

Saudi Aramco Forms and Data Sheets SA 2716-ENG

Specification Sheet of Air Cooled Heat Exchanger

SA 6238-ENG

Data & Operating Limits - Air Cooled Heat Exchangers

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3.2

Industry Codes and Standards American Society of Mechanical Engineers ASME SEC II, V & VIII

Boiler and Pressure Vessels

American Petroleum Institute API STD 661

Air Cooled Heat Exchangers for General Refinery Services

API Guide for Inspection of Refinery Equipment, Chapter VII 4

Definitions Alteration: is a physical change to a component described on the original Equipment Data Sheet that affects the pressure containing capability of the heat exchanger. Corrosion Allowance: is any metal thickness in excess of the minimum thickness required by pressure design. Corrosion Rate: is the amount of metal thickness loss that occurs during a fixed time period and is usually measured on mils per year (mpy). Inspector: is a member of the proponent's Operations Engineering Inspection Group or is an assigned Shops Inspector. Integrity: means soundness - i.e., freedom from flaws or defects. Equipment Data Sheet: is a document furnished by the Manufacturer certifying that materials, construction, and workmanship conform to Company and industrial requirements. Minimum Required Thickness, (Tm): as defined in ASME SEC VIII, is the calculated thickness required based on the design pressure and temperature exclusive of corrosion allowance. When the Tm limit is reached, action must be taken to repair, retire, or derate the equipment. Repair: is the work necessary to restore a heat exchanger to a safe operating condition. Rerating: refers to any change, i.e., temperature, pressure, thickness, etc., which would affect the maximum allowable working pressure. This change is to be documented by revising the Safety Instruction Sheet and the Equipment Data Sheet. Safety Instruction Sheet (SIS): gives the minimum allowable thickness based on the temperature and pressure for each component, and specifies test pressures (Refer to SAES-A-005). Page 3 of 8


Representative Specimen Tube: is a tube removed from the top or bottom row for destructive testing to evaluate corrosion damage. 5

Responsibilities of Inspector 5.1

Review the past history of the exchanger.

5.2

External Inspection

5.3

5.4

5.2.1

Look for and record any evidence of leakage around the nozzles, flanges, threaded plugs and rolled joints.

5.2.2

Check for signs of nozzle pipe strain and external corrosion.

5.2.3

Ultrasonically gage the thickness of header boxes and nozzles.

5.2.4

Establish the corrosion rates and check the remaining thickness against the tm (Refer to Safety Instruction Sheet)

5.2.5

Recommend repairs as necessary.

Exterior of Finned Tubes 5.3.1

Note the condition of the fins and the possible need for cleaning or straightening.

5.3.2

Check the exterior of the tubes for any mechanical damage, discoloration that may indicate leakage, or corrosion attack.

5.3.3

Look for any evidence of vibration.

5.3.4


Housing 5.4.1

Inspect the light gage steel housing enclosing the tubes for general condition.

5.4.2

Inspect the top and bottom structural retaining members.

5.4.3

Inspect all bolting for tightness and that the shroud is not vibrating against the tubes causing fretting.

5.4.4

Insure the shipping bolts between the housing and both header boxes are removed. The unit cells shall be allowed to expand freely when put in service.

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5.4.5 5.5


Internal Inspection 5.5.1

5.5.2

Header Boxes and Nozzles 5.5.1.1

A minimum of 10% of plugs should be removed from each end of the tube sheets. The sample should include representative plugs from each row of tubes.

5.5.1.2

If any fouling or corrosion is evident remove all plugs from the tube sheets.

5.5.1.3

Check the headers and nozzles, before cleaning, and determine whether there is any evidence of corrosion, erosion, or scale deposits.

5.5.1.4

Check the nozzle gasket surfaces, if possible.

5.5.1.5

Examine the plug sheet holes, plugs and gasket surfaces for stripped threads and/or galvanic corrosion.

5.5.1.6

Inspect plugs and plug sheets for impingement damage by the process stream.

5.5.1.7


Tubes 5.5.2.1

Check the rolled joints at the tube sheet for leakage.

5.5.2.2

Inspect the tubes inlets at the tube sheet for signs of erosion or corrosion.

5.5.2.3

Inspect the interior surfaces of the tubes with a boroscope for cleanliness, general corrosion and pitting. If corrosion is a problem, request Magnetic Flux Leakage (MFL) testing, Eddy Current testing or any other applicable Non Destructive Testing (NDT) from Operation Inspection Division (OID) to get accurate measurement of pitting depth, cracks and average wall thickness.

5.5.2.4

If NDT MFL results indicate the need for additional tube bundle evaluation, remove specimen tubes) for corrosion evaluation.

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5.5.3

5.5.2.5

Before plugging any tube, make sure it has been cut. The difference in thermal expansion between the plugged tube and the operating tubes may damage the rolling joint of the plugged tube resulting in a leak.

5.5.2.6

Observe the number of tubes already plugged and record it in the equipment inspection records.

5.5.2.7

Consider retubing the bundle when 10% of tubes in any one pass or a total of 10% of the tubes in the bundle have been plugged.

5.5.2.8


Fan, Driver and Housing 5.5.3.1

Insure the motor start/stop buttons are locked out before entering the fan housing area.

5.5.3.2

Insure the fan and driver guards are intact.

5.5.3.3

Inspect the fan blades for general condition, cracking, checking and chipping. Commentary Note: Fan blades must be installed as balanced pairs to maintain a balanced fan.

5.6

5.5.3.4

Inspect the fan belts for excessive wear, cuts and general condition.

5.5.3.5

Inspect the clearance between the fan blade tip and the housing corrugated filler strips. Clearance should meet the manufacturer's recommendation for best efficiency.

5.5.3.6

If present, inspect the condition of the corrugated filler strips and retaining bolts.

5.5.3.7

Inspect the hub assembly for possible cracking. If dismantled, hubs should be penetrant tested.

5.5.3.8


Hydrostatic Test 5.6.1

Witness hydrostatic tests. Page 6 of 8


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5.6.2

Obtain test pressures from SIS sheets. Hold test pressures for a minimum of 1 hour.

5.6.3

Hydrotest bundle and inspect for leakage. Test media should either be sweet water or condensate to prevent corrosion of tubes prior to startup (Refer to 32-SAMSS-011, paragraph 7.3.4 and SAES-A-007).

5.6.4

Plug all leaking tubes with tapered plugs of the same material as the tube. Drive a plug into each end of the leaking tube. Do not seal weld plugs.

Corrosion Rates, Remaining Life and Inspection Interval 6.1

Establish the corrosion rates of all the component parts of the heat exchanger.

6.2

Use the established corrosion rate and calculate the remaining life of all the components and tm for structure.

6.3

If needed, either make repairs to ensure the exchanger is good for the next scheduled run period or revise the EIS to a shorter inspection interval.

Recommendation for Repairs 7.1

Prepare the repair recommendations after inspections have been completed and corrosion rates established.

7.2

Obtain concurrence of the Operations Engineering Group where material changes, special welding procedures, etc., are a part of the repair recommendations. The Inspection Department and Consulting Services Department should be consulted in instances of unexpectedly high equipment deterioration or unusual operating conditions.

7.3

When retubing is necessary, the proponent Operations Engineering Unit shall concur that the tube material is adequate for the process conditions.

Alterations and Additions 8.1

Insure that a repair procedure has been established that will maintain the code integrity of the equipment before any repairs, alterations or additions are made.

8.2

Verify that the proper materials have been purchased and they are stamped per company and code requirements.

8.3

Verify that welding procedures and welders are qualified.

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8.4

Verify that pre and post weld heat treatment or stress relieving procedures meet code requirements.

8.5

Insure that radiographic techniques employed meet code requirements. Review and interpret all radiographic films per code requirements.

8.6

Determine if magnetic particle and/or dye penetrant examinations are required by the company and code requirements

Rerating Because of Operating Changes In Temperature or Maximum Allowable Working Pressure (MAWP) 9.1

Insure that the rerating is established in accordance with the requirements of the code revision applicable at the time of rerating.

9.2

Obtain from Operations Engineering the approved revised data sheet (SA 2716-ENG) and revised Safety Instruction Sheet (SA 6238-ENG).

9.3

Insure that a new nameplate is attached to the exchanger showing the rerated conditions.

9.4

Witness the hydrotest required to establish the rerating.

Records 10.1

Maintain a permanent and progressive set of records for each exchanger. These records shall contain copies of the Equipment Data Sheet, Safety Inspection Sheets (SIS), exchanger number, current condition of the equipment, previous repairs, alterations, rerating, corrosion rates, and remaining life predictions.

10.2

Review records when operating conditions change which could affect the corrosion rates. New corrosion evaluations and run length should be calculated.

Safety 11.1

Insure personal safety and that of any persons involved during inspections of equipment.

11.2

Insure that equipment is isolated from all sources of liquid, gases or vapors, prior to making the internal inspection.

11.3

Insure the motor start/stop buttons (both local and remote) are locked out before entering the fan housing area.

18 April 2009

Revision Summary Editorial revision to change the primary contact. Revised the “Next Planned Update”.

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32-SAIP-11

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