Procedure for Inspection Recalibration and Testing of Pressure Safety Valves

8/19/2019 Procedure for Inspection Recalibration and Testing of Pressure Safety Valves

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Pressure Safety Valves Inspection, Testing, Re - Calibration, and Certification Procedures

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PROCEDURES FOR PRESSURE SAFETY VALVESINSPECTION, TESTING, OVERHAULING, RE-CALIBRATION AND CERTIFICATION


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CONTENTS Page

1.0 Introduction 31.1 Scope 31.2 Definitions of Terms 31.3 Inspection And Recalibration Plan 5

2.0 Pressure Testing Requirements 5

2.1 Repair/Overhaul Requirements 62.2 Safety Requirements 62.3 Cleanliness 62.4 Personnel Qualification 7

3.0 PSV Testing and Recalibration Procedures 73.1 Introduction 73.2 As-Received, “Pre-pop” Test 73.3 Dismantling, Inspection and Overhauling of PSVs 83.4 Conventional (Spring Loaded) Safety Relief Valves 8

3.4.1 Cold Set Pressure Test 83.4.2 Seat Tightness Test 9

3.4.3 Body Leak Test 94.0 Pilot Operated Valves 104.1 Inspection Testing Repair and Setting of Pilot – Operated Valves 104.2 Types of Pilot Operated Valves 104.3 Definition of Terms for Pilot Operated Valves 104.4 Test Procedures 11

4.4.1 Introduction 114.4.2 Test Procedure Set Up 114.4.3 Set Pressure Adjustment 114.4.4 Reseat Adjustment 114.4.5 Performance Check – Relieving Pressure 11

4.4.6 Performance Check – Dome Pressure 114.5 Leakage Test 124.5.1 Leak Test Procedure – Complete Valve Assembly 124.5.2 Low Pressure Leakage Check 124.5.3 Pressure Leakage Check 124.5.4 Main Valve Function Check 13

5.0 Inspection and Replacement of Rupture Disks 136.0 Inspection and Testing of Pressure and/or Vacuum Vent Valves 147.0 Location Security 158.0 Reporting and Certification 15

8.1 Reporting 15

8.2 Certification 15 Appendix A: Annotated Schematic Drawing of Pressure Safety Devices Appendix B: API 527 Maximum Seat Leakage Rates for Metal – Seated PSVs Appendix C: Example of Pilot Valve Performance Requirements (Gas or Liquid Service) Appendix D: Example of Pilot Valve Performance Requirements (Snap Action) Appendix E: Example of Pilot Valve Performance Requirements (Modulating Action) Appendix F: Pressure Safety Valve Overhaul Report Format Appendix G: Pressure Safety Valves Test Certificate and Calibration Report Format Appendix H: Movements Report for Pressure Safety Valves


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1.0 Introduction

Pressure Safety Valves are safety critical components and are covered by national legislation(MOSR, 1997) and company general specification GS EXP 211- Plant Integrity MinimumInspection Requirements (Section 3.8) for periodic in - service inspection and calibration.

The service conditions of pressure safety valves vary widely and so exist in different areas of

the process criticality matrix. However, unless a formal Risked Based Inspection approach isadopted, (which decision may be taken in the future by Head of Asset Integrity), all pressuresafety valves are inspected and recalibrated after not more than 30months in service ( perMOSR, 1997) or after any lifting and /or passing during normal service conditions.

1.1 ScopeThis procedure specifies EPNL’s general requirements for inspection, testing, overhauling,repairs and recalibration of PSVs at Test Room/Workshops. However, it shall besupplemented by a number of work instructions (WIs).Coverage is limited to conventional spring loaded; balanced bellows; pilot operated devices;rupture or busting disk; thermal expansion relief valves and vacuum breakers which forms

majority of protective devices used in EPNL.(Hydraulic spill valves, integral to pumps, are not considered to be PSV’s. These shall bemaintained along with their associated equipment)

1.2 Definitions of Terms

Relief Valve: A relief valve is a spring-loaded pressure relief valve actuated by the static pressure upstreamof the valve. The valve opens normally in proportion to the pressure increase over theopening pressure. A relief valve is primarily used for liquid service.

Safety Valve: A safety valve is a spring-loaded pressure relief valve actuated by the static pressureupstream of the valve and characterized by rapid opening or pop action. A safety valve isnormally used for gas or vapour service.

Safety Relief Valve: A safety relief valve is a spring-loaded pressure relief valve that may be used as either asafety or relief valve depending on the application.

Pressure Relief Device: A pressure relief device is actuated by inlet static pressure and designed to open during an

emergency or abnormal conditions to prevent a rise of internal fluid pressure in excess of aspecified value.

Conventional Pressure Relief Valve: A conventional pressure relief valve is a spring- loaded pressure relief valve whoseperformance characteristics are directly affected by changes in the back pressure on thevalve.


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Balanced Pressure Relief Valve: A balanced pressure relief valve is a spring loaded pressure relief valve that incorporates ameans for minimizing the effect of back pressure on the performance characteristics.Pilot Operated Pressure Relief Valves:

A pilot operated pressure relief valve is a pressure relief valve in which the main valve iscombined with and controlled by an auxiliary pressure relief valve.

Cold Differential Test Pressure:Cold differential test pressure is the inlet static pressure at which a pressure relief valve isadjusted to open on the test stand. This test pressure includes corrections for serviceconditions of back pressure and/or temperature.

Popping Pressure:Popping pressure is the value of increasing inlet static pressure at which the disc moves inthe opening direction at a faster rate as compared with corresponding movement at higher orlower pressures. It applies only to safety or safety relief valves on gas or vapour service.

Overpressure:

Overpressure is a pressure increase over the set pressure of a pressure relief valve, usuallyexpressed as a percentage of set pressure.

Set Pressure:Set pressure is the value of increasing inlet static pressure at which a pressure relief valvedisplays one of the operational characteristics as defined under "opening pressure”, “poppingpressure”, or “start-to-discharge pressure” depending on service or as designated by theapplicable code or regulation. It is one value of pressure stamped on the pressure relief valve.

Reseating Pressure:Reseating pressure is the value of decreasing inlet static pressure at which the valve disc re-

establishes contact with the seat or at which lift becomes zero.Lift:Lift is the actual travel of the disc away from closed position when a valve is relieving.

Blow-down:Blow-down is the difference between the set pressure of a pressure relief valve and actualreseating pressure expressed as a percentage of the set pressure.

Back Pressure:Back pressure is the static pressure existing at the outlet of a pressure relief device due to

pressure in the discharge system.Thermal Expansion Relief Valve:

A Thermal expansion relief valve is a device releasing hydrocarbon trapped inside a capacity(usually a pipeline section) submitted to heat input in order to maintain pressure below designpressure. The acronym TSV is used.

Bursting or Rupture Disk: Rupture disk or bursting disk it is a type of sacrificial blind spade designed to burst at a certainlevel of pressure contained in the sensitive element to protect.


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Vacuum Relief Valve: A Vacuum Relief Valve is a Pressure Relief Device designed to admit fluid to prevent anexcessive internal vacuum; it is designed to re-close and prevent further flow of fluid after normalconditions have been restored.

EPNL Serialisation Numbers:This is a six digit number generated by UNISUP (SAP) to track PSV’s movement since they

are not treated as a functional location, but as equipment. For PSVs not bearing this number,it has to be requested for the Asset Integrity Section’s Technical Clerk and hard stamped onthe flange of the PSV before overhaul or recalibration.

1.3 Inspection And Re-calibration Plan

A “general ” Inspection and recalibration programme of all PSVs due for inspection andrecertification shall be issued by the Asset Integrity Section from SAP to the GeneralMaintenance Contractors (GMC). This shall be defined for a rolling twelve months on amonthly basis.

A “detailed ” rolling twelve months’ Inspection and recalibration programme of all PSVs mustbe provided by the relevant GMC monthly for EPNL approvals by Maintenance and AssetIntegrity.

The plan shall be sent to: DGM’s JV Onshore/Offshore Field Operation Managers, Onshore/Offshore Methods Managers, Onshore /Offshore Respective Site Managers (RSES) Head of Process / Treatment Onshore/Offshore Head of Maintenance Onshore/Offshore

Head of Asset Integrity Senior Integrity Methods Engineer

2.0 Inspection and Testing Requirements

2.1 Selection of Sub-Contractors and Personnel

Testing, calibration, and certification of EPNL’s PSVs shall only be carried out (in shop or onsite) by a Contractor who has the “Special Category” Permit to operate as an Oil IndustryService Company, awarded by the Department of Petroleum Resources (DPR) and who hasbeen approved by EPNL after an audit visit (by Total HSE and Integrity Sections) to check for

compliance of facilities and Procedures to TOTAL’s Standards.The respective site GMCs shall make available to EPNL a list of proposed Valve Techniciansfrom each Contractor for approval.In addition to excellent safety orientation, personnel shall have acquired adequate technicalknowledge and practical experience in the related duties. He/she should be able to carry outcalibration, overhauls and testing of valves according to approved procedures andmanufacturer’s recommendations.


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2.2 Safety Requirements

Adequate measures shall be taken to protect personnel against possible hazards.These must include, but not be limited to:

Barriers/shielding must be considered, particularly for high pressure gas tests Using properly inspected, calibrated and certified testing components, e.g. pumps,

compressors, pressure control devices, piping system, pressure hoses, and pressuregauges etc. Positioning the valve discharge nozzle to prevent exposure of personnel to a sudden

blast of air, water, or other projectiles from the valve. Utilisation of personal protective equipment e.g. ear defenders, eye goggles, safety

boots, etc. Not attempting to test valves at pressures above that for which the test bench is

designed.

2.2 Testing, Overhaul and Re-certification Equipment

The following minimum provisions shall be mandatory for carrying out pressure test on valves: The test room shall be equipped with pneumatic facilities capable of providing a supplyof air or nitrogen at a pressure above the pressure required for the range of valves tobe tested at the valve test bench.

There shall be hydraulic facilities for the hydraulic testing of valves. Quick change adaptors for different sizes of valves. All necessary fixtures, fittings and tools required for the test set up. Calibrated and fully certified pressure gauges adequate for the working range pressure

(Gauge range should be maximum of three times the test pressure).The frequency of calibration shall not exceed one year and the calibration certificatesshall be available at all times for sighting.

In addition, the testing facility shall be equipped with the equipment and tools listed below asa minimum for overhaul and repairs of metal seated and soft-seated valves.

A Standard test bench fitted with all necessary accessories Lapping machine and accessories. Lapping stones. Surface plates. Grinding kit. General hand tools. An optimum stock of repair kits for replacement of spare / soft goods i.e. soft seats,

seals, gaskets, etc which should be available before removal of the valve from situ

Test fluid to be employed should be filtered.


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3.0 PSV Testing and Recalibration Procedures

3.1 IntroductionIt is mandatory that an EPNL representative and DPR personnel must be afforded theopportunity to witness the dirty inspection / pre-pop and overhaul of PSVs.

For a valve in Gas service, the test medium must be Nitrogen or dive-quality air (or other gas

as specified). A valve in liquid service can be tested by liquid or gas.Prior to testing, the test equipment should be blown out with dry, high pressure air to removeany dust or particles which may have accumulated. The final testing shall be witnessed bypersonnel from EPNL’s Integrity Section and DPR

Note: Currently, DPR require 14 days’ notice, in writing, for planned PSV re-certification.

3.2 As-Received, “Pre-pop” TestThe valve shall be “pre-popped” to determine how it would have performed in service.If heavy fouling of the valve is observed, it should be considered whether a pre-pop would

damage the valve, in which case the pre-pop can be waived, but such a decision must not betaken lightly as it is very important to know how the valve would have performed in service.The nature of the fouling must be investigated (initiated by the Site Integrity Engineer) andmeasures taken to prevent future re-occurrences

The inlet side of the valve to be tested should be carefully cleaned to ensure that there is nodirt, dust or loose particles adhering to the inside of the nozzle or the underside of the disc.

A satisfactory test is one were the valve lifts within -10% and +5% of the CDTP. This test isdone by mounting the PSV on the bench test block and slowly increasing the pressure on thevalve. The relieving pressure is determined by watching a pressure gauge and noting the

point at which the valve pops or relieves.However, if the valve does not pop before reaching an inlet pressure of 120% of the CDTP,the test shall be aborted and the valve considered as stuck shut (failed to lift).This failure to lift shall be directed to the Head of Asset Integrity for furtherinvestigation on a case-by-case basis.

Notes: 1) Valve Previously in Service : - If, initially, the valve opens at between 105% and 120%

of the CDTP, it shall be popped for a second time to assess how it could have performedin service. If the second test falls between 90% and 105% of the CDTP, then both

readings are recorded and the test is deemed to be acceptable 2) New Valve : - To be pre-popped 3 times.

1 st Test; - For alignment (can rectify any out-of-alignment from transporting)2nd and 3 RD Tests:- to prove repeatability. The 3 rd value is recorded as the value set forservice

The “As-received” tests results shall be recorded on testing report form, Appendices F and G. An acceptable pre-pop is one where the final lift falls within the limits set pressure tolerancesspecified in 3.4.1 below.


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3.3 Dismantling, Inspection, and Overhauling of PSVs

The valve shall be carefully dismantled in accordance with manufacturer’s manuals andrecommendations. At each stage in the dismantling process, the various parts of the valve shallbe visually inspected for evidence of wear, deformation and corrosion.

After dismantling, each part shall be cleaned and examined for wear, corrosion or damage.

Seating surfaces on the disk and nozzle shall be inspected for roughness or damage whichmight result in valve leakage. The spring should be checked for evidence of cracking ordeformation. The fit between the guide and the disk or disk holder should be checked for properclearance and visually inspected for evidence of scoring. The bellows in balanced-type valvesshould be checked for cracks or other failures that may affect performance. The details of thisinspection, including general internal and external condition, shall be recorded in the PSVsOverhaul Report Sheet and the test certificate and report. See Appendices F and G.

Parts that are worn or damaged must be replaced or reconditioned. Damaged springs ordamaged bellows must be replaced. Replacement parts shall be obtained from the originalmanufacturer of the Pressure Relief Valve. The seating surface of the disc and nozzles may be

machined or lapped if evidence of wear or damage is found. Seats lapping shall be carried outaccording to the manufacturer’s recommendations and procedures by using proper lappingblocks and correct lapping compound grades.

After the valve has been inspected and re-conditioned, it must be re-assembled in accordancewith the manufacturer’s instructions. Once the re-assembly is completed, the Pressure ReliefValve is ready to be tested according to the procedures described hereafter.

Note for Valves Which Have Been Passing in Service : Where possible a repair kit should beused for a valve which has been passing in service. If a new kit is used the next recertificationdate is from the date of fitting; if a new kit is not used and / or the passing valve has not been

overhauled, the next date of inspection runs from the previous full recertification

3.4 Conventional (Spring Loaded) Safety Relief Valves

3.4.1 Cold Set Pressure TestThe valve shall be mounted on the test bench in the vertical position and air pressure slowlyapplied to the valve inlet for cold set pressure taking into consideration correction factors fortemperature and back pressure based on the manufacturer recommendations. Valve upperand lower blow-down rings, where fitted, shall be adjusted as recommended by the valvemanufacturer. This procedure shall be repeated until the required cold set pressure is

obtained.

When the correct cold set pressure is obtained, the valve pops (lifts) and this should be withinthe set pressure tolerances specified by below. It is mandatory to verify that the obtained coldset pressure has remained unchanged by repeating the test – first for alignment, second andthird for repeatability. The value of the third lift shall be recorded in the test report.

±2 Psi (±0.13 Bars) for pressure up to and including 70Psi (4.8 Bars) ±3% of set pressure for pressure above 70Psi (4.8 Bars)


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The cold set pressure and spring adjustment shall be recorded and entered on the TestCertificate (See Appendix G). It is recommended that spring adjustment is measured withreference to the top face of the bonnet and not the top surface of the lock nut.

3.4.2 Seat Tightness Test

Following a successful cold set pressure test, the valve shall be fitted with a suitable flange at

its outlet orifice to test for tightness. This flange has a hole in the centre to take a “bubble testpot” built to API Standard 527 (see figure 6).

With the valve on the test bench in the vertical position, test pressure is adjusted to 95percentof the cold set pressure for valves whose cold set pressure is greater than 1015 Psi (70 Bars)and the leakage rate in bubbles per minute (BPM) determined.

For valve set between 1015 Psi (70 Bars) and 50 Psi (3.45 Bars), the test pressure shall beadjusted to 90percent of the cold set pressure and the leakage rate in bubbles per minute(BPM) determined.

For valves set at 50psi or less, the test pressure shall be held at 5psi below the cold setpressure immediately after popping and leakage rates in bubbles per minute determined.

Seat tightness test for Metal Seated valves are considered acceptable if leakage rates fallwithin limits specified by API Standard 527. See Appendix B. Notes:

1. The valve Technician must be able to determine the orifice size to apply the relevantacceptable BPM

2. It is permissible to release the pressure and then increase to 90% cold differential setpressure (CDSP)

3.4.3 Body Leak TestWith the valve remaining on the test bench an appropriate flange is fitted to its outlet andstatic test pressure is applied through the outlet flange. This pressure is equal to the valveoutlet flange rating or allowable back pressure whichever, is less.With pressure being maintained a soapy solution is applied to all the body and bonnet jointsto check for leaks. Test duration between 2-3 minutes.

For bellows fitted valves, the bellows tightness is tested by applying a low pressure (1 bar)through the valve outlet flange. A check for leaks using a soapy solution is then carried out tothe bonnet vent hole, the blow-down ring adjustment screw connections and the bonnet

flange joint. On satisfactory completion of the above tests the valve upper and lower blowdown rings, where fitted, are to be checked with reference to their initial setting. If anydifference is observed readjustment is to be made as advised by the manufacturer.


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4.0 Pilot Operated Valves

This section establishes the general procedure for assembly, functional testing and normalperformance requirements of pilot operated safety-relief valves. However, because of themany types of pilot operated valves available, the valve manufacturer’s recommendations forinspection, repair and testing for the specific valve should be consulted and followed.(Refer Appendices C, D & E for examples illustrating some of the numerous differences

between pilot operated valves).

4.1 Inspection, Testing, Repair and Setting of Pilot – Operated Valves

Inspection, testing, maintenance, and setting of the pilot mechanism may be handledseparately from the main valve.The pilot gets tested and re-certified. As a minimum the pilot valve shall be pre-popped,stripped, examined, cleaned, re-built, calibrated and recertified following valve manufacturer’srecommendations for inspection, repair, and testing.The main valve gets inspected:- As a minimum, the integrity engineer carries out a visualinspection of the main valve inlet and outlet (bearing in mind the specific service) and a visual

of the tie-in piping for cleanliness, fouling, corrosion, etc.If no problems are observed, the valve can be re-installed, using new gaskets.

Many of the considerations that apply to other pressure relief valves also apply to pilotoperated valves. The following is a list of additional considerations that apply:

Inspect soft goods (O – rings, diaphragms, gaskets) Check for plugging in pilot assembly and external tubing Check for material trapped in valve dome area Check all tubing fittings for leakage Inspect the pressure pick-up device and its orientation

4.2 Types of Pilot Operated Valves

There are two different types of pilot operated valves• Snap Action (Rapid full Opening and Closing)• Modulating Action ( Opens proportionally to the over pressure)

4.3 Definition of Terms for Pilot Operated Valves

Set pressure is that pressure at which the pilot valve relieves on increasing inlet pressure toreduce the dome pressure to 70% or less of supply. On snap action pilots the dome pressure

will decrease very rapidly. For modulating action pilots, the dome pressure will decrease inproportion to the rate of increase in supply pressure.

Cracking pressure is that inlet pressure at which first leak occurs at the pilot exhaust port onincreasing pressure.

Reseat pressure is that pressure where the dome pressure increases to 75% or more ofsupply. For "pop" action pilots this pressure is usually 90% to 92% of set pressure. Onmodulating action pilots, it will be 96% to 100% of set pressure.


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Reseat leakage is the leakage across the pilot valve seat at reseat pressure. For snap actionpilots this leakage should be zero at reseat. On modulating action pilots, leakage will occuruntil the supply pressure has decreased to the amount specified in the performancerequirements, usually 90% to 95% of set pressure.

Dome pressure is the pressure at the dome connection of the pilot valve.

4.4 Pilot Operated Valves: Test Procedures

4.4.1 IntroductionThe test medium shall be shop air or nitrogen at ambient conditions for all main valves and allgas service pilots, unless otherwise specified. Pilots for liquid service may be set on water.Full scale of the gauge used shall not be greater than three times set pressure.

All pilot valve assemblies shall be tested to make sure the correct dome pressure is obtainedto operate the main valve. The pilot supply pressure and dome pressure shall be recorded onthe test certificate and report (See Appendix G).

4.4.2 Test Procedure Set Up - Pilot

The following procedures shall be used to test the pilot valve, using air or nitrogen at ambienttemperature as the pressure medium for gas service pilots and water for liquid service pilots,unless otherwise specified.

Install the pilot valve on a test drum per Figure 4 and 5. The "dome" connection is a blindconnection with a pressure gauge to indicate dome pressure reduction at set pressure.

4.4.3 Set Pressure Adjustment

Adjust the spring adjusting screw to obtain the correct set pressure. Clockwise rotationincreases the set pressure. Tighten the locknut after adjustment is completed.

4.4.4 Reseat Adjustment

On all pilots except modulating pilots, adjust the blow down adjustment screw to obtain thedesired reseat pressure. Tighten the locknut after adjustment is completed.Note : The reseat value of the main valve with internal pressure pickup for the pilot will beapproximately 3% to 4% less than the reseat value of the pilot only on snap action pilots dueto the pressure loss in the dipper tube.

4.4.5 Performance Check - Relieving Pressure

Cycle the pilot a minimum of three times to make sure it is relieving and reseating atconsistent pressures. Increase the pressure very slowly in order to obtain an accuratereading of the relieving pressure and to detect any erratic performance.Note : Each step shall be completed before proceeding to the next step.


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4.4.6 Performance Check - Dome Pressure

Flow the pilot valve except at the set pressure to obtain the dome pressure reading. Ifsufficient gas capacity is not available to flow the pilot at the set pressure, read the lowestdome pressure at the time of reseat. This method is not applicable for modulating pilots. Forthe no-flow modulating pilot, increase the supply pressure to 110% of nameplate set. Thedome pressure must decrease to less than 40% of the supply.

4.5 Leakage Test

For gas service pilots, leakage shall be detected using a bubble tube tester of the type shownin Figure 6. For liquid service pilots, leakage shall be detected visually.

Slowly increase the pressure at the inlet port until leakage is detected at the pilot exhaustport. This pressure shall be recorded as the cracking pressure.

Further increase the pressure at the inlet port until the pilot actuates or "pops". This pressureshall be recorded as the set pressure. For the no-flow modulating pilot, no leakage at thepilot exhaust should occur with inlet supply pressure held constant and the dome pressurehas stabilized.

Shut off the inlet pressure to the test accumulator and allow the pilot to reseat. This pressureshall be recorded as the reseat pressure. For modulating pilots, reduce the inlet pressure ofthe test accumulator in accordance with the specified reseat pressure. Check the valve forleakage at the exhaust port.

Repeat the steps above a minimum of three times. The cracking pressure, set pressure andreseat pressure shall be within the limits for three consecutive cycles. The valve action shall

be consistent.

Slowly increase the inlet pressure until the leakage test pressure is reached. Maintain thispressure for one minute and check for leakage at the exhaust port and at the blow downadjustment. No leakage shall occur.

4.5.1 Leak Test Procedure - Complete Valve Assembly

Completely assemble the pilot on the main valve. Connect the main valve inlet to a pressuresource as shown in Figure 3. Shop air at ambient temperature shall be used as the testmedium unless otherwise specified. For liquid service valves, a leakage at the pilot exhaustnot to exceed 60 bubbles/minute is acceptable if no leakage occurred when tested on water.

4.4.2 Low Pressure Leakage Check

Slowly increase the inlet pressure to 30% of the set pressure. Check for main valve nozzle,seat, and piston seal leakage at the main valve outlet. No visible leakage shall occur in 15seconds. To help in seating the valve seat and piston seal, the valve may be actuatedseveral times.


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4.4.3 Pressure Leakage Check

Apply pressure to the inlet equal to 90% of the set pressure. Check for leakage at the mainvalve outlet. Using a suitable gas and air leak detector solution, check for leakage at the capseal and other pressure connections. No leakage shall occur at the valve outlet and novisible leakage shall be detected at the cap seal or other pressure connections in one minute.Where superimposed back pressure is specified, the downstream or exhaust connectionswhich are exposed to the back pressure shall be tested at 1.5 times the specified backpressure and all mechanical connections so pressurized will be checked for leaks. No visibleleakage shall occur in one minute using a suitable gas and air leak detector solution.

4.4.4 Main Valve Function Check

Caution : This test must be performed at a slow rate of pressure increase to insure that themain valve does not go into full lift. The pressure applied to the inlet is not to exceed 105% ofnameplate set pressure.

After completing the high pressure leakage check, verify main valve opening as follows.Remove the bubble tube leakage tester from the outlet flange and slowly increase the inletpressure above 90% of set pressure. Continue increasing inlet pressure until an audibledischarge at the valve outlet verifies main valve opening.


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5.0 Inspection and Replacement of Rupture Disks

Rupture disks are used in services where a large relieving capacity is required to give a rapiddrop in pressure. The disks are made from a wide variety of metallic and non-metallicmaterial. Rupture disks may be inspected visually.

Rupture Disks should be thoroughly inspected after removal from their operational location.

Inspection should include a check of flanges for leakage and a check of the disk for fatigue,corrosion, failure, and build up of coke or other foreign material that could adversely affect thedisk’s performance. They should be renewed as required, based on their reliability andcondition.

Because they cannot be tested, Rupture Disks should be replaced on a regular schedulebased on their application, the manufacturer’s recommendations, and past experience. Thisrecommendations and schedule must be provided by the Maintenance Department.

If a block valve is located ahead of the disk, the block valve should be locked open duringoperation. If replacement of the disk is necessary, the block valve should be locked closed

until disk installation has been accomplished. Normally in this case, a rupture disk cannot beinspected without being removed. Therefore, inspection of the disk should be part of theroutine developed for inspection of the Pressure Relief Valves.

A rupture disk installed upstream of the relief valve to prevent valve corrosion is normally setto burst either at the set pressure of the Pressure Relief Valves it is protecting or at apressure 3 % – 5 % less than the set pressure.

Caution : The relief valve must be designed so that it will not fail to open at its proper pressuresetting regardless of any backpressure accumulated between the valve disk and the rupturedisk. If backpressure builds up between an ordinary spring-loaded safety relief valve and a

rupture disk, the valve will not open at its set pressure. In this case, the valve should bereplaced by a specially designed valve such as a diaphragm valve equipped with a bellowsabove the disk.


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6.0 Inspection and Testing Of Pressure and/or Vacuum Vent Valves

The relieving devices on tanks may be separated into pressure and/or vacuum relief deviceson atmospheric tanks and PSVs on pressure storage vessels. The inspection, testing,maintenance, and setting of relieving devices on pressure storage tanks are similar to thoseof PSVs on process equipment. Pressure and/or vacuum vent valves on atmospheric tanksare designed to vent air and vapour from the tank during filling operation and to admit air

when the tank is drawn down. Because pressure and/or vacuum vent valves are incontinuous service, they are prone to failure by sticking unless examined periodically.

The inspection of each vent valve in place should include the checking of the dischargeopening for obstructions. The top of the valve should be removed and the pallets checked forfreedom of movement. Seats should be checked to ensure that there is no sticking orleakage, since the forces actuating the valve are small. If the valve has a flame arrester onthe inlet nozzle, it should be inspected for excessive fouling or plugging. If necessary, itshould be removed for cleaning.

Caution : Inspection of the flame arrester in service is important because any malfunction may

result in the loss of expensive equipment. Inspection, testing, maintenance, and setting ofpressure and/or vacuum vent valves should include the following special steps:

• Sticking should be corrected and prevented . The disks (pallets) of the devices should bechecked for sticking. If the disks are stuck, the product’s effect on the seal material and on thedisk material should be investigated. If necessary the seal material and the disk materialshould be changed.• The disk should be checked and maintained . Once a disk is removed, it should be cleaned,

and its mass should be determined. Check the mass against the mass required for thecorrect relieving pressure of the device. [The setting of a pressure-vacuum device dependson the mass of the disk compared to the area of the opening covered by the disk. Set

pressure is usually a standard ½ ounce per square inch (0.43 kPa), but may go as high as24 ounce per square inch (10.43 kPa)] If the mass is not correct, mass must be added orremoved until the correct mass has been achieved. Disk condition and serviceability shouldbe checked, and unusable disks should be replaced.

• The seats and pallets of the disk seating areas must be checked and cleaned.• The gaskets at the disk seating areas must be checked and, if necessary, replaced.• The protective screens must be checked for serviceability and, if necessary, renewed.• Hinges and hinge pins must be checked for operability and, as necessary, serviced,

lubricated, and replaced.• Any special coating used internally or externally on the body should be checked and, if

unserviceable, replaced.• The hood should be inspected and, if unserviceable, replaced.• The bolts should be checked and, as required, replaced.


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7.0 Location Security

Every adjustable part of the valve shall be double-checked for correct location and positioningafter testing. On completion of all works, on any type of valve, the spring adjustment must besecured by copper wire and a crimped lead seal

8.0 Reporting and Certification

8.1 Reporting

Reporting is to provide all related information for the tested valve as contained in appendicesB and C i.e. the as-received conditions; details of overhaul work performed, test results, etc.Minimum information required should include:

EPNL Number The "as-received" condition of the valve, and the pre-pop pressure.

Details of the inspection and repair/overhaul work performed. Condition of the valve following overhaul and/or re-setting. Final pressure test results in figures i.e. cold set pressure, bubbles/minute, and spring

adjustment (MM) position of blow down ring(s) etc. A statement that the valve has satisfactorily passed the required tests. Other related Valve's information e.g. name plate data, trim details, duty etc. shall be

recorded only once, for registration and inspection purposes. Such information shouldbe amended, whenever necessary, to indicate any related changes, or modifications.

8.2 Certification

Final tests of valves performed by approved contractors shall be signed off by ValveTechnician and personnel from DPR and EPNL’s Asset Integrity Section who witnessed thetest. The signed off Test Certificate and Calibration Reports shall be in quadruple copies.These copies shall be distributed as follows: Asset Integrity Office Copy, Field Copy,Contractor’s Copy and DPR’s Copy


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Appendix AAnnotated Schematic of Pressure Safety Devices


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Appendix A (contd)

Figure 4 – Bubble test for Pilot Valves

Figure 5 – Set Up for Testing of Pilot Valves

Figure 6 – Bubble Test Set Requirements


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Appendix B


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Appendix C

PILOT OPERATED SAFETY RELIEF VALVESTANDARD PERFORMANCE REQUIREMENTS

(GAS OR LIQUID SERVICE)

SET PRESSUREThe set pressure is where the dome pressure equals 70% + 2% of the supply pressure. Theindicator must operate at nameplate set +3%.

Set Pressure ASME Performance Tolerance Above 70 psig + 3% of the specified set pressure (1)[Above 483 KPAG]70 psig & below + 2 psig [13.8 kPa] (2)[483 KPAG & below]

CRACKING PRESSURE

Set Pressure Cracking Pressure (Min.)15 - 3705 psig 94% of the specified set pressure[103-25545 KPAG]

RESEAT PRESSUREThe reseat pressure is where the dome pressure equals 75% + 2% of the supply pressure.

Set Pressure Reseat Pressure15 - 70 psig 3 psig [20.7 KPAG] below specified set[103-276 KPAG] pressure71 - 3705 psig 96% to 100% of the specified set[283-25545 KPAG] pressure

LEAKAGE TEST PRESSURENo leakage shall occur for one minute at pressures between 30% of specified set pressureand the cracking pressure when checked with the supply pressure held constant. At

pressures below 30% of set, the leakage rate for gas service pilots shall not exceed 20bubbles/minute. For liquid service pilots there shall be no leakage. Pilots shall seal bubbletight at 5.0 psig [34.5 KPAG] for gas service pilots. For liquid service pilots there shall be novisible leakage.

DOME PRESSURE TEST

Set Pressure Dome Pressure15-3705 psig Less than 40% of Supply at 110% of[103-25545 KPAG] specified set pressure

NOTES: EPNL Recommended Setting Tolerance

(1) Adjust set pressure 0% to 2% above nameplate.(2) Adjust set pressure 1/2 psig [3.45 KPAG] to 1 1/2 psig

[10.34 KPAG] above nameplate.

(3) For ISO-DOME pilots, adjust regulator for Dome supply to92% + 2% of nameplate set.


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Appendix D


(Snap Action)

SET PRESSURE

Set Pressure ASME Performance Tolerance Above 70 psig + 3% of the specified set pressure (1)[Above 483 KPAG]70 psig & below + 2 psig [13.8 kPa] (2)[483 KPAG & below]

CRACKING PRESSURESet Pressure Cracking Pressure (Min.)15 psig & above 95% of the specified set pressure[103 KPAG & above]Below 15 psig 92 1/2 % of the specified set pressure[Below 103 KPAG]

RESEAT PRESSURESet Pressure Reseat Pressure (3)15 psig & above 92 1/2% + 1% of the specified set pressure[103 KPAG & above]Below 15 psig 92 1/2% + 1% of the specified set pressure[Below 103 KPAG]

LEAKAGE TEST PRESSUREThere shall be no leakage for one minute at pressures below the cracking pressure or at thereseat pressure.

DOME PRESSURE TESTThe dome pressure shall decrease rapidly, as with a snap and shall not exceed 20% of theinlet pressure while the pilot valve is venting at the specified set pressure.

NOTES: EPNL Recommended Setting Tolerance

(1) Adjust set pressure 0% to 1% above nameplate.(2) Adjust set pressure 0 psig to 1 psig [0 to 6.89 KPAG] above nameplate.

(3) To be checked with pilot flowing.


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Appendix E


(Modulating Action)(Gas or Liquid Service)

Set Pressure

The set pressure is where the dome pressure equals 70% + 2% of the supply pressure. Theindicator must operate at nameplate set +3%.

Set Pressure ASME Performance Tolerance Above 70 psig + 3% of the specified set pressure (1)[Above 483 KPAG]70 psig & below + 2 psig [13.8 KPAG] (2)[483 KPAG & below]

Cracking Pressure

Set Pressure Cracking Pressure (Min.) All 95% of the specified set pressure

Reseat PressureThe reseat pressure is where the dome pressure equals 76% + 2% of the supply pressure

Set Pressure Reseat Pressure All 99% to 100% of the specified set pressure

Reseat Leakage Pressure (Pilot Seat)

Set Pressure Reseat Pressure (Min.)

All 95% + 1% of the specified set pressureLeakage Test PressureNo leakage shall occur for one minute at pressures below the cracking pressure or at thereseat leakage pressure when checked per 7.2.6.

NOTES: EPNL Recommended Setting Tolerance(1) Adjust set pressure 0% to 1% above nameplate.(2) Adjust set pressure 0 psig to 1 psig [0 to 6.89 KPAG] above nameplate.

It is preferable that pilot valves are set separate from the main valve. However, the complete

assembly, main valve and pilot valve, can still be tested on the test bench following the sameprocedure.


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Appendix F

Pressure Safety Valve - Overhaul ReportNote: This is the PSV workbook in Unisup

NAMES(Check data, nameplates, tagnumbers etc) Tick Box00ND 0-Inspection NotDone/Not inspectable Inspection Not Done/Not inspectable

01NF 1-No finding

No finding - No action - Any data is correct and up todate; Name Plate is still in place and data in line withany documentation

02ED 2-Erroneous data

Minor defect - No action - Data discrepancies comparedto equipment drawings, equipment data sheet, PID,FAME+ or SAP data base

02ID 2-Lack ofIdentification/marking

Minor defect - No action - Nameplate is missing; lack ofidentification, tag no., PK post, marker, SWL, etc


Defective - Some action required - Data discrepanciescompared to equipment drawings, equipment datasheet, PID, FAME+ or SAP data base


Defective - Some action required -Nameplate is missing;lack of identification, tag no., PK post, marker, SWL, etc


Action needed immediately - Data discrepanciescompared to equipment drawings, equipment datasheet, PID, FAME+ or SAP data base


Action needed immediately - Nameplate is missing; lackof identification, tag no., PK post, marker, SWL, etc

DIRTYS(Check internals for debris,scale, clogging etc)00ND 0-Inspection NotDone/Not inspectable Inspection Not Done/Not inspectable

01CL 1-Clean Good condition/As new - No action - No significantDebris/Deposits, Corrosion products.

02CT 2-Clogged/Plugged

Minor defect - No action - Clogged/Plugged (Heatexchanger, Air cooler and Boiler tubes, or PSV nozzle.); not compromising process

02DD 2-Debris/Deposits(sand, sludge, wax...)

Minor defect - Minor Debris/Deposits quantity (Anytype/size); not compromising process

02SC 2-ScalesMinor defect - No action - Scale; not compromisingprocess


Defective - Some action required - Clogged/Plugged(Heat exchanger, Air cooler and Boiler tubes, or PSVnozzle.); possibly compromising process


Defective - Some action required - MediumDebris/Deposits quantity (Any type/size); possiblycompromising process

03SC 3-Scales Defective - Some action required - Scale; possiblycompromising process


Action needed immediately Clogged/Plugged (Heatexchanger, Air cooler and Boiler tubes, or PSV nozzle.);compromising process


Action needed immediately - Major Debris/Depositsquantity (Any type/size); compromising process

04SC 4-Scales Action needed immediately - Scale; compromisingprocess

PSDBS(Check the general conditionof the valve body)


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00ND 0-Inspection NotDone/Not inspectable Inspection Not Done/Not inspectable01BG 1-Body in goodcondition

Good condition/As new - No action - Body in goodcondition

02BE 2-Body externallydamaged/corroded

Minor defect - No action - Body externallydamaged/corroded

02BI 2-Body internallydamaged/corroded

Minor defect - No action - Body internallydamaged/corroded


Defective - Some action required - Body externallydamaged/corroded


Defective - Some action required - Body internallydamaged/corroded


Action needed immediately - Body externallydamaged/corroded


Action needed immediately - Body internallydamaged/corroded

PSDIS(Check the condition of thevalve components)00ND 0-Inspection NotDone/Not inspectable Inspection Not Done/Not inspectable01IG 1-Internals in goodcondition

Good condition/As new - No action - All internal parts ingood condition

02DS 2-Discdamaged/corroded Minor defect - No action - Disc damaged/corroded02MI 2-Miscellaneous partscondition

Minor defect - No action - Miscellaneous internal partsdamaged/corroded

02NO 2-Nozzledamaged/corroded Minor defect - No action - Nozzle damaged/corroded02SG 2-Springdamaged/corroded Minor defect - No action - Spring damaged/corroded03BU 3-Burst discdamaged/corroded

Defective - Some action required - Burst discdamaged/corroded (corrosion, buckling, pinholes.)

03BW 3-Bellowdamaged/corroded

Defective - Some action required - Bellowdamaged/corroded

03DS 3-Discdamaged/corroded

Defective - Some action required -Discdamaged/corroded

03MI 3-Miscellaneous partscondition

Defective - Some action required -Miscellaneousinternal parts damaged/corroded

03NO 3-Nozzledamaged/corroded

Defective - Some action required - Nozzledamaged/corroded

03SG 3-Springdamaged/corroded

Defective - Some action required - Springdamaged/corroded

04BU 4-Burst discdamaged/corroded

Action needed immediately - Burst discdamaged/corroded (corrosion, buckling, pinholes.)

04BW 4-Bellowdamaged/corroded Action needed immediately - Bellow damaged/corroded04DS 4-Discdamaged/corroded Action needed immediately - Disc damaged/corroded04MI 4-Miscellaneous partscondition

Action needed immediately - Miscellaneous internalparts damaged/corroded

04NO 4-Nozzledamaged/corroded Action needed immediately - Nozzle damaged/corroded04SG 4-Springdamaged/corroded Action needed immediately - Spring damaged/corroded

Enter results belowSTATUS Blow off pressure first lift Bar

STATUSPost Overhaul Results - Blowoff pressure Bar


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Appendix G

Test Certificate and Calibration Report of Pressure Safety Valves

Client: Date: Work Order/P/Order No: Ref: Valve Type (Conventional / Pilot / Bellows):Location/Protecting Equipment:

VALVE DETAILSManufacturer: Cold Diff Set Pressure:Type (Pilot): Inlet Size/Rating: Type (Main Valve): Outlet Size/ Rating Tag No: Orifice Size: Serial No (Pilot) Temperature:

Serial No(Main Valve) Blow down (%Sp) Set Pressure: EPNL Serial No:

PRE-POP REPORTTest Medium: Pre-Pop pres./Blow-off pres. first lift:Subsequent Lifts Gauge No & Cal. Date: Not pre-pop, why? Carried out by: Sign: Date:

GENERAL CONDITION OF THE VALVE BODYBody Material: Body General Condition: State specific defects& if any:

GENERAL CONDITION OF THE VALVE COMPONENTSBonnet: Spring Material; Part number & Condition: Disc material; Part number & Condition:

Nozzle material: Part number & Condition: Disc holder: O-Ring: Guide:

Adjacent screw/nut: Diaphragm: Bellows Material: Burst disc:

GENERAL CONDITION OF THE MATERIAL


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THICK AS APPLICABLEClean

Clogged/pluggedDebris/Deposits (Sand, Sludge, Wax.)

Scales

POST OVERHAUL RESULTSSet Pressure: CDSP: Leakage Test (No. of Bubbles/Min)

CONCLUSION:


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Pressure Safety Valves Inspection, Testing, Re - Calibration, and Certification Procedures Appendix H

Movements Report for Pressure Safety Valves

Where the original valve is reinstated in its original tag location only Section 1 should be completed.In all other cases all three sections should be completed.

1. VALVE WAS REINSTATED AFTER RECERTIFICATION

TAG LOCATION MANUFACTURER'S SERIAL NUMBEREPNL SERIALNUMBER

2. VALVE WAS NOT REINSTATED AFTER RECERTIFICATION

VALVE WAS MOVED TO: TAG LOCATION - (ENTER TAG NUMBER)

ON-SITE STORE - ( TICK IF TRUE)

EPNL WAREHOUSE - (TICK IF TRUE)

CONTRACTOR'S PREMISES -(ENTER NAME OF CONTRACTOR)

VALVE WAS SCRAPPED: (TICK IF TRUE)

3. REPLACEMENT VALVE WAS INSTALLED

MANUFACTURER'S SERIAL NUMBEREPNL SERIALNUMBER

VALVE ORIGINATEDFROM: TAG LOCATION - (ENTER TAG NUMBER)

ON-SITE STORE - ( TICK IF TRUE)

EPNL WAREHOUSE - (TICK IF TRUE)

CONTRACTOR'S PREMISES -(ENTER NAME OF CONTRACTOR)

Procedure for Inspection Recalibration and Testing of Pressure Safety Valves

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