Section 15 — Inspection

In-Plant Inspection of Pressure Relief Valves

IPE Engineering Practice IPE-EP-15-4-9

Document number: IPE-EP-15-4-9 · Section: 15 — Inspection

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SCOPE

This procedure defines the requirements and specifies responsibilities for the maintenance testing, inspection, repair, setting and establishing safe operating intervals for and reliable operation of plant pressure–relieving devices.

Any deviation from this Practice must be approved by the procedure described in EP 1–1–3.

An asterisk (*) indicates that an action by the Owner is required, or that additional information is furnished by the Purchaser.

REFERENCES

The latest edition of the following standards and publications are referred to herein:

STANDARDS AND PUBLICATIONS

DEFINITIONS

Balanced Pressure Relief Valve – A safety relief valve that incorporates means, such as a pressure balancing bellows or piston, for minimizing the effect of back pressure on the performance characteristics, such as, opening pressure, closing pressure, lift, and relieving capacity.

Blowdown System – A system that disposes of discharges of liquids or condensable vapors from units such as fluid catalytic crackers (FCCs) and cokers, as well as liquid discharges from pressure relief valves.

Inspector – A Inflection Point Engineering, LLC appointed engineer or inspector.

• Inspector – A IPE appointed engineer or inspector.
• Performance Testing – New and repaired pressure relief valves shall meet Manufacturer’s performance criteria for new pressure relief valves when tested on the test bench.
• Pressure Relieving Device – Any of the many available devices for pressure or vacuum relief or a system where over pressure may occur.
• Pilot Operated Pressure Relief Valve – A valve that has the major flow device combined with and controlled by a self–actuated auxiliary pressure relief valve.
• Relief Valve – An automatic pressure relieving device actuated by the static pressure upstream of the valve, which opens in proportion to the increase in pressure over the opening pressure (typically used primarily for liquid service).
• Rupture Disk – A thin metal diaphragm held between flanges and constructed to burst at a predetermined inlet static pressure (they are sometimes used on the upstream side of pressure–relief valves to protest against corrosion or plugging).
• Safety Relief Valve – Normally used in gas and vapor service or in liquid service, is an automatic pressure relief device suitable for use as either a safety or a relief valve, depending on the application.
• Safety Valve – Normally used in gas and vapor service or in steam and air service, is an automatic pressure relieving device actuated by the static pressure upstream of the valve and characterized by rapid full opening or pop action.
• Pressure Relief Valves – A generic term applied to relief valves, safety valves and safety relief valves.
• Pretest – The essential “as–received” bench test applied to all safety relief valves prior to cleaning and dismantling for servicing except those in services where the deposits in the safety relief valve are extremely hazardous such as HF acid. It is the basis for determining valve operating intervals.
• Set Pressure – Measured in pounds per square inch gauge, is the inlet pressure at which the pressure relief device is adjusted to open under service conditions. In a safety or safety relief valve in gas, vapor, or steam service, the set pressure is the inlet pressure at which the valve pops under service conditions. In a relief or safety relief valve in liquid service, the set pressure is the inlet pressure at which the valve starts to discharge under service conditions. For temperature service, the “cold set” test bench pressure is a corrected pressure that has an incremental pressure added to the service “set pressure”.
• SRV Test Report – The form detailing all of the important aspects of pressure relief valve testing and maintenance which is to be conscientiously completed and signed by the machinist and his supervisor with a copy being sent to the Inspection authority or his designee. This form is essential to safely establish future valve operating and test intervals.
• Stationary Equipment Inspection Authority – For the purposes of this Practice the Stationary Equipment Inspection Authority is the Plant Chief Inspector, Inspection Supervisor, or Chief Inspection Engineer as defined by the Plant management.
• Test Bench – The shop test stand where new and used pressure relief valves are pre–tested and cold set after servicing before being carefully transported to their service location.

• Valve Repair – Maintenance valve repair of a pressure relief valve may be the replacement, re– machining, or cleaning of any critical part, lapping of the valve seat and disk, or any operation which may affect the flow passage, capacity, function or pressure retaining integrity of the valve.

• VR Stamp – The National Board of Boiler and Pressure Vessel Inspectors valve repair organization authorization stamp where the supporting quality control procedures include control of certification of the National Board.

INSPECTION AUTHORITY PERSONNEL

• Personnel performing inspection of pressure–relief devices shall be qualified in accordance with EP 15–3–1 and shall be familiar with the pressure relieving device inspection requirements and guidelines in the API publications: API 510, API 570, and API 576 and the National Board Inspection Code, NB–23.

REPAIR ORGANIZATION

• As a minimum, the organization shall have a fully documented quality control program meeting the requirements of API 510.
• Personnel (Plant or Contract) servicing and performing repairs on safety relief devices as well as their support organization must be knowledgeable and provide qualification by virtue of a documented in–house training program available for review by the Inspection Authority.

DESIGN AND ACQUISITION

• All pressure–relief valves and devices and their locations will be numbered and identified. The Inspection Authority is responsible for assuring a master identification list is maintained and is responsible for assuring a unique number is issued to anyone initiating the placement or replacement of a pressure relieving device.
• This unique pressure relieving device number will, be included on all drawings, engineering information and documentation relative to the pressure relieving device. Ultimately this identification number will be stamped on the valve body.
• Each new or revamped pressure relief device installation shall be sized by Plant Process Engineering, Control Systems Engineering Specialists or Plant Engineering. The same group shall also be responsible for maintaining these calculation records in appropriate files for future reference.
• Design will include consideration for avoiding excessive pressure drop on inlet piping; drainage of blowdown system piping; proper piping support to minimize loading on the pressure relieving devices, and the adequacy of the blowdown system itself (see API RP 521).
• When pressure relieving devices are selected, consideration shall be given to plant standardization and availability.
• When a pressure relief device is ordered, copies of the order (including the assigned number) and available documentation shall be sent to the Inspection Authority so that appropriate monitoring records may be established. The Inspection Authority will then forward the documentation to the group maintaining and filing such records.

• Ordering specifications should require that all new pressure relieving devices be stamped by the Manufacturer with the appropriate ASME Code stamp and that documentation be provided listing all part numbers, critical part dimensions and tolerances, and material specifications. The Manufacturer will also furnish a Data Sheet providing all pertinent pressure relieving device

data such as capacity and ring settings.

INSPECTION

• A number of specific items should be checked during periodic external visual inspections of in– service pressure relieving devices including:
• Required block valve locks and car seals in the visible area are intact.
• Rupture disk gages under relief valves are serviceable.
• Bellows vent piping is discharging in a safe location.
• Observe if outlet piping may be warm, frosted, screeching or responds to an ultrasonic listening device (indicating a leak).
• Small nipples should be properly supported.
• Check if associated piping is under any undue stress.
• Record such observations and include them in future installation improvement recommendations.
• Prior to a Major Maintenance Shutdown or occasion requiring pressure relieving device servicing, the Inspection Authority will assure a listing of necessary pressure relieving device service work is issued to the appropriate personnel.
• Shutdown field inspection tours should be made so that the Inspector can observe open relief device installations. Visually inspect the open systems, note any dirt or accumulations in the vicinity, and check flange faces. Record all information of import for future installation improvement decisions (see Section 13.5 below).
• Plant Machine Shop and Contractor Shop inspection tours should be made when devices are being serviced and reconditioned for quality control purposes by the Inspector or a designated representative.
• The Inspection Authority or his designee will be consulted on all Plant and Contract Machine Shop problems that cannot be handled by the Foreman or Supervisor.

SRV REPAIR CONTRACTORS

• Contractor shop inspection tours of prospective pressure relief device maintenance shops and facilities shall be made by Inspection Authority designated personnel for new Contractors or when recent experience with a Contractor does not exist. References, past performances and workmanship will be considered in making recommendations.
• SRV Repair Contractors shall have the equivalent of a National Board “VR” Stamp and a test bench accumulation capacity of at least 4 cubic feet.
• If deemed necessary by the Inspection Authority, an Owner or contract inspector may be assigned to contractor shops to handle any valve problems.

• The Owner’s plant maintenance shop or the Contractor will receive copies of the Owner’s Pressure Relief Device Testing and Repair procedures and will appropriately complete an approved SRV Report Form which will be signed by the Machinist, signed by his Supervisor and a copy sent to the Inspection Authority.

TRANSPORTATION

• Operating safety is dependent upon the proper handling, transportation and care of pressure relief devices at all times.
• Valves being removed from service must be carefully protected prior to being shop pre–tested before reconditioning. These pretest results must be accurate because they may be used to determine safe future operating intervals.
• Pressure relieving devices are delicate, carefully–machined or lapped instruments (especially large, low pressure valves). New, reconditioned or used valves coming out of service must be handled very carefully, not jarred or dropped, and transported and stored in the upright position strapped to a pallet.
• When a valve is removed from service and at any time during transport, flange gasket surfaces must be protected from damage. Nozzles and openings (including inlet and outlet piping) should be blocked from water and foreign objects entering.
• Large valves must be handled with suitable rigging to prevent them from being roughly handled or dropped. Newly reconditioned valves in the shop should be enclosed in plastic bags or otherwise protected before being transported to the field.

TESTING

• (*) Upon arrival in the shop new and used valves shall be pre–tested in the “as–received” condition on a suitable test bench with the appropriate testing media and proper procedures shall be used. Except those valves in services where the deposits in the safety relief valve are extremely hazardous such as HF acid need not be tested, unless special precautions are taken to protect test bench personnel. This shall be performed prior to any disassembly or cleaning, unless prior approval is granted by the Owner to clean before testing. The results of this testing will be recorded on the SRV Test Report.
• The valve test bench with air and/or gas, water and steam facilities shall have ample test volume and adequate flow. Calibrated gages shall have a recorded maximum calibration period of six months.
• New valves will be stamped with the identification number prior to being tested and set. Used valves will have their numbers verified. All changes will be recorded in the remarks section of the SRV Test Report. All previous or inappropriate numbers must be removed by grinding.
• SRV Test Report comment terms are as follows:
• Coked – Evidence of residue from petroleum distilled to a solid.
• Cold Set – The result of a service temperature correction pressure that is added to the set pressure (see Section 3.0 above).
• Corroded – Loss or metal by chemical reaction.
• Dirty – Having some accumulation of dirt.

• Leak – Record (L) in the “popped at” column for a leak when a valve leaks too much to pop on the pretest. A valve “leaks” when it passes below 90% (94% for steam) of its set pressure but achieves a pop.
• Oily – Having a heavy coating of oil.
• Over pop – The technical condition of having popped above the tolerance range of 10% for Section VIII pressure relief valves and 6% for Section 1 safety valves. This condition will be determined by the Inspection Authority and will influence future operating intervals.
• Parts – Indicate parts needing to be ordered for the future in the “remarks” column.
• Plugged – Blocked with any material which may or may not influence the pretest pop pressure, but may reduce flow capacity.
• Remarks – SRV Test Report column where any significant or helpful information should be placed such as:
• Reason for and degree of leaking.
• Reason for under pop, over pop or sticking.
• Special maintenance performed.
• Parts of valve replaced.
• New parts or valve to be ordered.
• Name of Inspector authorizing any special change.
• Stuck – The condition where a valve fails to pop on the pretest at 130% of its set pressure. It is the point where the pretest must be terminated for safety reasons of exceeding valve safety factors.
• Tight – A term indicating a “tight” seat on popping or re–popping.
• Pretest results as well as significant observations and results of repairs shall be accurately recorded on SRV Test Report by the Machinist, signed by both the Machinist and the Supervisor or Foreman and sent to the Inspection Authority. Pre–testing shall be in accordance with the following criteria:
• Pretest the “as–received” valve unless it is totally plugged per the Inspector’s agreement. In this case, record (PLUGGED) and note the inlet or outlet location.
• Record in the “remarks” space a test valve “leak” under 90% of the cold set pressure (94% for steam), the pressure of the first leak ( PSI), and if the leak is too severe to achieve a pop, (L) in the “popped at” column.
• Record the initial pop or relief pressure. If the valve fails to pop, discontinue the test at the maximum test pressure of 1.3 times the set pressure, and record (STUCK).
• If the initial pop or relief pressure is more than 10% (6% for steam valves) greater than the cold set pressure, this valve has “over popped”. Re–pop the valve and record the second or retest pop pressure ( PSI) in the “remarks” space.
• Record the reseating pressure and whether it is tight (TIGHT).
• (*) Where the Inspection Authority permits under certain conditions, or in units such as the HF Alky, field testing of valves using equipment employing a hydraulic–actuated test technique may be appropriate. Contract personnel used for this operation shall be certified by their employer. Copies of the certification program shall be submitted to the Inspection Authority prior to the field testing.

MAINTENANCE AND REPAIR

• (*) Only following the “as–received” pretest pop procedure (see Section 10, above) may a valve be disassembled for cleaning and repair. All cleaning methods must have prior approval from the Inspection Authority.
• Facilities must be provided to segregate all valve parts during dismantling and parts must be properly marked to prevent mix–up. If a valve number is changed, all old or confusing numbers shall be removed by grinding, new numbers stamped, and the old number recorded in the remarks section of the SRV Test Report.
• At each stage of the dismantling process, parts should be inspected for evidence of wear or corrosion. The stem, guide, disk and nozzle should be visually inspected and the bellows checked for cracks or distortion that would affect performance.
• All parts must be properly cleaned and measured to conform with Manufacturer’s drawings or literature. Nameplates and seats shall be protected when cleaning. Seats should be checked for conformance with Manufacturer’s tolerances. Springs should be checked for corrosion, deep pits, cracks or deformation. The spring free height should be verified.
• Following cleaning, a thorough visual check, including NDE techniques as applicable, shall be made of all components and special conditions noted on the SRV Test Report.
• Damaged parts must be replaced or reconditioned and worn or damaged seating surfaces machined or lapped in accord with Manufacturer’s recommendations. These actions shall also be recorded.
• When a pressure–relief valve has been repaired, a suitable repair nameplate or tag shall be attached to the valve adjacent to the original stamping or on the cap. Included shall be the name of the repair organization, repair date and owner’s valve identification number. If the set pressure has been changed, the old set pressure shall be marked out and the new pressure and capacity indicated. Illegible or missing Manufacturer’s information shall be restored.
• Valve stamping shall be done before the valve is reassembled or tested and set for assembled valves.
• Reassemble the valve in accordance with the Manufacturer’s instructions. The nozzle and seating surfaces should not be oiled.

SETTING

• All valves, including those newly purchased, shall be tested with the appropriate medium before being installed to demonstrate cold set pressure, tightness, response to blowdown if required, and seat tightness in accordance with the Manufacturer’s recommendations and appropriate ASME Code Sections. They shall be transported to the field in strict accordance with Section 9 of this Practice.
• ASME Code Section I steam valves shall be tested and set with steam. Other steam valves may be tested with air or gas.

• General service valves should be tested and set using water for valves in liquid service and air or gas for valves in vapor or gas service.

ON–STREAM ADJUSTMENTS

• When a safety relief valve leaks or malfunctions in–service to the point where operations are seriously impacted, the Inspection Authority or his designee must be notified by Operations prior to any on–stream adjustments. Inspection is the only organization authorized to make or oversee on–stream adjustments including the removal of any seals or locks. Note: Pilot operated safety relief valves should not be adjusted on–stream because of the small bore threaded nipple between the main valve and the pilot valve.
• The leakage or malfunction must be verified. A thorough analysis of possible causes of the problem will determine whether solutions considered are safe. Safe activities must be performed in direct coordination with Operating personnel who will continuously monitor pressure and process conditions during adjustments.
• A qualified Machinist or other specialists should assist the Inspector as needed.
• If corrective action is unsuccessful or considered unsafe, alternatives may be considered. These include lowering the process pressure, the use of an existing block valve in order to remove and repair or replace the relief valve, the use of a stopple, the use of hydraulic–actuated test equipment, or a shutdown if the process leakage is not acceptable.
• For valves that are chronic problems, consideration should be given to improving the valve design or making the valve available for in–service repair as follows:
• By installing a three–way valve with two safety valves
• By installing a block valve.
• By installing a rupture disk.

OPERATING INTERVALS

• Specific operating intervals between pressure relief device maintenance testing and repair or replacement shall be determined for each installation. Safety considerations shall supersede all economic considerations. Interval determination shall be based on experience and performance in the service concerned and will be determined by the Inspection Authority or his designee.
• Operating intervals will normally coincide with unit turnaround intervals, or multiples thereof, but will be dictated by valve performance in each location. For valves or units needing to increase their operating periods:

• For pressure relief valves having satisfactory performance (no sticking or repeated over popping on the previous “as–received” pretest pop), and where the possible service contamination factors are expected to remain relatively constant, the recommended valve operating interval may be increased to one and a half times the satisfactory interval up to a maximum of ten years (API 510 Pressure Vessel Code, National Board Inspection Code, NB–23).
• For pressure relief valves evidencing poor performance (sticking or over popping on the “as–received” pretest pop), the interval may remain the same for a single offense, but should be reduced by approximately 25% for each consecutive poor performance.
• When valve installations have been upgraded or when the process environment no longer results in poor performance (by virtue of consecutive satisfactory pre–pop tests), test intervals may again be increased in accordance with Item 1 above.
• For valves that have chronic problems or where their intervals differ from the unit interval, improvements may be considered in accordance with Section 13.5 above.
• For pressure relief valves reported as leaking on the pre–pop test but perform satisfactorily otherwise, the test interval shall remain the same until the valve exhibits no leaking performance.

RECORDS AND DOCUMENTATION

• The Inspection Authority is responsible for assuring that a record of each pressure relieving device is maintained. The record should include design and engineering data and a history of inspection and test results.
• SRV Test Report forms shall be made available by the Inspection Authority to assist in the identification and reporting of all Plant relief device testing and activity. They shall be completed and signed by the Machinist testing and servicing the valve, signed by the Supervisor or Foreman and a copy forwarded to the Inspection Authority.
• Records shall be kept in such a manner that intervals, schedules and test information are readily available to maintain relief devices and determine their operating intervals.
• Reports that identify deficient devices and that will lead to an early disposition of the deficiencies shall be circulated to Plant Management.

RESPONSIBILITIES

• The Owner’s Engineering Services group shall serve as final authority on pressure relieving device and blowdown system design.
• The Plant Inspection Authority, Inspector or delegate shall:
• Assign personnel associated with pressure relieving device Inspection.
• Serve as final authority on all matters concerning Plant pressure relief device inspection, testing, repair and setting. Provide necessary schedules, lists (including lists of deficient installations) and SRV Test Report forms to those requiring them.
• Provide Plant pressure relief device test and service procedures.
• Provide for, store and evaluate inspection and test results, determine operating intervals, and develop performance improvement methods, reports and recommendations.
• Oversee on–stream adjustments and serve as consultant on performance problems.

• Recommend special parts, materials, changes and improvements for relief systems and devices as appropriate.
• Assure that pressure relief device records, files and computer systems are maintained.
• Evaluate potential Contractors’ shop work quality and capabilities.
• Provide pressure relief device training and technological updating for the Inspectors.
• The Plant Process Engineering group, the Operations Development Department, the Control Systems Engineering group or the Plant Engineering group shall:
• Provide pressure relief device and system design and upgrade engineering.
• Review outside engineering and store all engineering data and calculations for plant pressure relieving devices and systems.
• Select and initiate new or upgrade/revamp pressure relief device and system orders and send them to the Operations Supervisor with a copy to the Inspection Authority.
• The Plant Operations Department Supervisor or delegate shall:
• Approve all work orders for new pressure relief devices and parts for units under their authority.
• Check that all pressure relief devices have been correctly reinstalled and tagged following removal for testing and maintenance.
• Regularly check and report any problems to the Inspection Authority including:
• That there are no gags, blinds, closed upstream or downstream block valves or piping obstructions preventing proper relief function.
• That bellows vents are open and clear with piping routed to a safe location.
• That all locks (relief valve block valves locked open) and car seals are in place and intact.
• The Plant Maintenance Department Supervisor, Machine Shop Foreman, Shop Equipment Resource Allocator or delegate shall:
• Provide Contract supervision when pressure relief valve servicing and maintenance is contracted out.
• Remove, reinstall, properly test, service and maintain, and exercise care in handling and transporting all pressure relief devices (per Section 9 above).
• Salvage parts in useable condition and maintain them in an orderly used–parts inventory in the Machine Shop.
• Establish the level of spare parts inventory and initiate orders to maintain appropriate pressure relief device spare parts in the Machine Shop or Warehouse.
• Supply spare parts to pressure relief valve Contractors as needed and reorder as necessary.
• Consult with the Inspection Authority on special problems that cannot be solved in the Shop.
• Be sure the Machinist completes and signs the SRV Test Report form for all valves tested and serviced. A copy shall be returned to the Inspection Authority after the Supervisor, Foreman, or Shop Equipment Resource Allocator checks it for replacement parts used this time and parts needed in the future and signs it.
• Provide training and updates for Machinists and Supervisors responsible for servicing pressure relief devices and keep records of the program plus certifications available for observation.

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