Maintenance and Testing Of PZVs

Note: The source of the technical material in this volume is the ProfessionalEngineering Development Program (PEDP) of Engineering Services.

Warning: The material contained in this document was developed for SaudiAramco and is intended for the exclusive use of Saudi Aramco’s employees.Any material contained in this document which is not already in the publicdomain may not be copied, reproduced, sold, given, or disclosed to thirdparties, or otherwise used in whole, or in part, without the written permissionof the Vice President, Engineering Services, Saudi Aramco.

Chapter : Instrumentation For additional information on this subject, contactFile Reference: PCI11006 D.W. Buerkel on 874-7339

Engineering EncyclopediaSaudi Aramco DeskTop Standards

Maintenance And Testing Of PZVs

Engineering Encyclopedia Instrumentation


Saudi Aramco DeskTop Standards

Content Page

PZV DOCUMENTATION REQUIREMENTS .................................................................... 1

T&I Interval .............................................................................................................. 2

Special T&I Cases..................................................................................................... 5

Installation ................................................................................................................ 6

SHOP TESTING REQUIREMENTS ................................................................................... 7

Purpose Of Shop Testing........................................................................................... 7

Test Stand Design Requirements ............................................................................... 8

Pressure Source ............................................................................................. 8

Test Drum and/or Accumulator...................................................................... 8

Test Flange Mounting Assembly (Test Flange)............................................... 9

Test Gage/s.................................................................................................... 9

Interconnecting Piping And Valves ................................................................ 9

Set Pressure Test......................................................................................................10

Cold Differential Test Pressure......................................................................10

Functional Test.........................................................................................................11

IN-PLACE TESTING .........................................................................................................19

Reasons for In-Place Testing ....................................................................................19

Set Pressure Test......................................................................................................21

Functional Test.........................................................................................................22

Table of Figures Page

Figure 1. Timeline of Events in the Life History of a PZV......................................... 1

Figure 2. T&I & Maintenance Forms........................................................................ 4



Saudi Aramco DeskTop Standards 1

PZV DOCUMENTATION REQUIREMENTS

Figure 1 shows a timeline for typical events in the "life history" of a PZV. This module willdescribe the testing, inspection and maintenance that occurs from the time the valve is installeduntil it is removed and replaced. Figure 2 identifies the documentation that is required for theevents shown in Figure 1 including the types of documents , their numbers, names and associatedSaudi Aramco Standards.

Figure 1. Timeline of Events in the Life History of a PZV

Testing and Inspection (T&I) of relief valves is conducted periodically based on an intervalauthorized on form 3099A, and initiated by Form 981-5, "Maintenance Work Order" (981-5MWO). T&I and maintenance are performed by highly trained, and certified Saudi Aramcotechnicians. SAEP-1134 and Form 3099A, as discussed in PCI-110.03, outline the qualificationsand certification procedure for relief valve (RV) technicians. A review of the Certificationrequirements SAEP-1134 will provide an appreciation of the high degree of skill required forcertification as a relief valve Technician.




Maintenance (disassembly, inspection, reassembly, calibration, and testing) is required on all reliefvalves at each third T&I interval, or more frequently if the installation has a history of problems.Maintenance is always performed when problems are evident during any T&I (e.g., a stuck diskor leaking valve).

Detailed observation, careful workmanship, and meticulous record-keeping are required forproper relief valve maintenance. Inspection records begin when a PZV is installed and continueswhenever it requires testing and maintenance. A relief valve summary report, "Relief ValveMaintenance Report" form 3750-ENG (3750-ENG) is filed at the completion of each 981-5/-1MWO. (A 981-1 MWO is an unscheduled MWO). Observations and measurements recordedduring T&I, and maintenance determine the future T&I schedules.

Careful workmanship is a combination of general skills associated with all relief valvemaintenance, and specific requirements based on work controls (site specific procedures) and themanufacturer's maintenance manuals. Each class of relief valve requires special tools, testequipment, and consumable parts that are listed in the site procedures and the manufacturer'smanuals. relief valve handling will vary with valve size, weight, and process service. Safe handlingof relief valves should be, as outlined in the Aramco maintenance procedures.

Regardless of the size and type of relief valve, recording observations of abnormalities,measurements and the adjustments of important parts is a critical T&I and maintenance task.Checklists that condense crucial information from shop manuals while also providing a form forrecording observations and measurements are an efficient record-keeping tool.

When a relief valve is returned to service after T&I and maintenance (if required) a form 3750-ENG is issued and then entered into the relief valve database SAMMS/RV. Note that form 3750is a T&I and maintenance summary report.

T&I Interval

Figure 2 is a table of the documents and records used by Saudi Aramco. These are the documentsthat will be discussed in this module. The role or purpose of each document can be related to thetypical events of PZV maintenance cycles and life history shown in Figure 1.

The guidelines for setting up T&I schedules and intervals are found in Sections 4 and 5 of SAEP-319. Initial T&I intervals are entered in form 3099A after sizing and selection of a PZV.Likewise, all subsequent interval schedule changes require form 3099A approvals. SAEP-319allows for T&I non-scheduled intervention without 3099A approval. However, unscheduled T&I(using form 981-1), and T&I schedule delays are either initiated by, or require operationsmanagement approval.




A general time line for T&I interval schedules is presented in SAEP-319, Sections 4 and 5. Thescheduled intervals can be any of the following:

• Normal T&I interval . Operations originates this schedule from the relief valvedatabase using 3750-ENG reports.

• Decreased interval time for scheduled T&I if there is a problem with the relief valve.This schedule is recommended by operations using the sidebar on Form SBX1506.

• Increased interval time for T&I schedules of 'clean' relief valves is recommended byForm SBX1506. At the third T&I interval , the relief valve is disassembled andinspected. If the relief valve passes this inspection, SBX1506 will recommend anincrease in T&I interval up to the maximum allowable of 36 Months. The maximumT&I Intervals for the following are exceptions:

Instrument Air 60 Months

Steam Boilers 12 Months

Lube Oil 48 Months

Note again that form SBX 15066 is only advisory. To initiate or change a relief valve intervalrequires approval using a form 3099A. This form is issued by operations and approved as noted inSAEP-319. Interval decreases recommended by SBX1506 are authorized by the local InspectionUnit Supervisor and the Operations Foreman. The interval increases, or extensions, recommendedby SBX1506 are authorized by the Supervisor of Operations Engineering and the OperationsSuperintendent.

Forms management is conducted by the relief valve database in the Saudi ARAMCO computer.PCI-110.03 discussed form 3099A authorization data entry, and SBX1506 has been reviewedabove. Two additional administrative forms: 981-5 MWO, and 3750-ENG are directly associatedwith the relief valve database.

Relief Valve T&I and maintenance is initiated by receipt of a computer generated form 981-5MWO. At the completion of each 981-5 MWO, a form 3750-ENG is issued. Form 981-1 MWOsare manual versions of the form 981-5 MWOs that are issued by operations when it is necessary,or expedient to intervene in a relief valve T&I schedule. Test and Inspection is necessary whenoperations observes PZV malfunctioning (e.g., chattering ).




Summary Table of Major Documents & Records Covered in Module 6:

FORM PURPOSE

3099ASAEP-1131

RV AUTHORIZATION FORM Provides authorityfor installing an RV, setting T&I Schedules, andretiring RVs

981-5SAEP-310

MAINTENANCE WORK ORDER FORM Generated by the SAMMS/RV computer databasedirecting a shop to perform T&I and maintenance on anrelief valve. The T&I schedule is taken from form3099A authorization.

981-1SAEP-319

MAINTENANCE WORK ORDER FORM Issuedby operations to direct a shop to perform unscheduledT&I and Maintenance on an relief valve.

3750-ENGSAEP-003-2

Summarizes results of T&I and Maintenanceperformed on a relief valve.

SBX1506SAEP-319

SAMMS/RV COMPUTER GENERATED FORMEmploys logic and key fields from 3750-ENG torecommend T&I and Maintenance schedule changes.

2760SAEP-319

Request for approval to deviate from inspectionschedule. Used by a shop to extend a scheduled T&Iand maintenance requirement of a MWO.

Figure 2. T&I & Maintenance Forms

It is expedient to test and inspect relief valves when associated equipment, and/or a process unit isshutdown for repair or maintenance. An unscheduled relief valve T&I results in an intervalrearrangement (maintains the same interval but extends the next T&I schedule date) without3099A authorization when the relief valve is to be found "clean" and free of problems. For reliefvalves that have problems, initiate SBX1506s as usual.




Form 981-5 is issued approximately two months before the scheduled T&I date, and usuallyincludes a group of relief valves that require T&I. The form is self explanatory and includes spacefor administrative entries that are appropriate for:

• The headers for a work description, an MWO issue date, work location (shop),plant, unit, and plant number.

• The body includes: relief valve number, relief valve location, relief valve SetPressure, relief valve Cold Differential Test Pressure (CDTP), Vacuum Set Pressure(VAC PRESS), and Due Date (for conducting T&I).

A noteworthy symbol on form 981-5 MWO is the Star (*), indicating that certain relief valvesrequire disassembly as part of their T&I. Note that the SAMMS/RV database is used toadminister the maintenance activities that operations initiates.

Form 3750-ENG is used to summarize the results of T&I and maintenance performed on a PZV.SAEP-1133 provides detailed instructions for completing form 3750-ENG, which is entered intothe relief valve database after 'sign-off' using the SAMMS/RV subsystem program. Key fields inform 3750-ENG trigger SBX1506. These fields, as listed in SAEP-319 section 5.4., initiate thefollowing:

• "Clean" relief valves, after their third T&I interval, cause SBX1506 to recommendan interval increase of six months.

• Disassembled codes "S", "B", or "A", or Repair Work Summary Code "M" causeSBX1506 to recommend the following: (1) a review by engineering and aninspection, and (2) to reduce the T&I interval.

SAEP-319, section 5.5.4 addresses an additional T&I related form: "Approval Request to Deviatefrom Inspection Schedule," Form 2760. This form is used to extend the T&I schedule. A delayedT&I schedule can be approved by the local Operations Superintendent for up to three months, orone month for each year of the specified interval, whichever is less. Form 2760 "ApprovedRequest to Deviate from Inspection Schedule" is required when the delay exceeds these intervals.Approved form 2760s are submitted by the Operations Foreman or Commissioning Supervisor tothe relief valve Administrator one month prior to the delay.

Special T&I Cases

"Mothballed" relief valves are listed as Inactive in the relief valve database. PZVs on mothballedequipment undergo an annual visual inspection as part of the required equipment inspectionprocedure. SAEP-319, section 5.6 outlines T&I requirements for mothballed relief valves. Reliefvalve database records are activated as part of the recommissioning of mothballed equipment.




Pressure Test relief valves are maintained for protection of equipment undergoing pressure testingabove their MAWP. Pressure Test relief valve T&I intervals are outlined in SAEP-319 section 5.7otherwise Pressure Test RVs' are maintained as any other relief valve.

Installation

Relief valve installations are designed and engineered by Saudi Aramco piping engineering.Installation drawings for each relief valve are part of the initial construction package for the reliefvalve. Prior to commissioning an installation, three independent inspections and form 3099Asign-offs' are required by SAEP-318. This procedure and other requirements of SAES J-600 werereviewed in PCI-110.03 and PCI-110.04

When an installation of a relief valve is inspected, the manufacturer's nameplate information, andSaudi Aramco tag number are checked against the information on the PZV ISS. The physicalinstallation is checked for conformance with the 'approved' installation drawings. If the projectedequipment is a pressure vessel, nameplates and tags are checked against the SIS for the vessel.




SHOP TESTING REQUIREMENTS

Testing relief valves involves proving that the relief valve will open within the specified limits ofits set point and not leak when closed. Relief valves equipped with lifting devices can be tested todetermine if the disk is stuck to the seat without verifying that the relief valve will open (pop) atthe required set point and/or leaks when closed. In Module 6, testing will mean that the reliefvalve opens within the prescribed set point, and does not leak beyond prescribed limits whenclosed.

Purpose Of Shop Testing

The purpose of shop testing is to test a relief valve in a maintenance shop rather than in the fieldand/or in-place. As stated above, testing requirements are issued on Saudi Aramco form 981-5/-1MWO. Test results must be entered on form 3750-ENG and the AMMS/RV database.

Specific details for preparing a relief valve for testing are listed in the manufacture's maintenancemanual that was shipped with the relief valve. These requirements will vary with each relief valveand will be based on the relief valve serial number and Saudi Aramco tag number.

The advantages of shop testing are convenience and safety. However, economic factors andinstallation details sometime affect testing locations. Large relief valves are often disassembled bythe manufacturer before shipping. It is sometimes more economical to test these valves in-place.However, if the valve requires disassembly under the 981-5/-1 MWO, and it must be returned tothe shop. (Relief valves with body's welded at the inlet can be disassembled and the bodyinspected and maintained in place. Only the valve 'top-works' is inspected and maintained in theshop. At one time, this practice was common on steam pressurized equipment.) Such relief valvescan usually be tested in the shop prior to reinstallation. relief valves on pressurized steamequipment certified under ASME Section I shall be tested in-place. To save time in the field, theselarge ASME Section I relief valves can be calibrated and checked in the shop prior to installationand in-place testing.

Air and water are common shop testing fluids although some shops have inert gas (Nitrogen orArgon), and some shops have steam available for testing relief valves. Since maintenance shopsdo not, or cannot, perform capacity testing of relief valves testing fluid is not an issue. The reliefvalve set point in the shop will always be tested at the Cold Differential Test Pressure (CDTP) ofthe relief valve. CDTP compensates for both process fluid discharge temperature and/or backpressure on the discharge of the relief valve. The value of CDTP is provided by the relief valvemanufacturer and usually stamped on the nameplate of the relief valve. It is also listed on the ISS,3099A, and 981-5/-1 MWO forms for the relief valve.




Since capacity is not related to the pressure at which a relief valve opens (distinguishable aspopping pressure), it is not necessary to compensate for any difference in fluid properties whentesting the relief valve. Note again, that the manufacturer has certified the relief valve for acertain capacity based on fluid properties provided by the user specification. If the specified fluidproperties were wrong the relief valve capacity will not meet manufactured certification. If amothballed relief valve is recommissioned for a service using a different process fluid, it should bereturned to the manufacturer for recertification; or, if the properties of the new service are closeto those of the old service the manufacturer should be consulted before recommissioning the reliefvalve.

Test Stand Design Requirements

Shop testing of relief valves is usually conducted on a Relief Valve Test Stand (test stand). Teststands consist of four major components:

Pressure Source

Pressure sources pressurized fluid for testing the relief valve. Pressure sources can be an aircompressor, and/or water hydraulic pump (the standard Saudi Aramco pressure source.): bottledgas: liquified gas and vaporizer combination: low-pressure instrument air from plant utility: or avacuum pump.

The pressure source/s must have a pressure rating and flow capacity, which meets or exceeds therequirements of the test stand.

Test Drum and/or Accumulator

The function of the test drum/and or accumulator is to provide a reservoir of fluid suitable fortesting the relief valve. A 5 cubic foot (cuft) accumulator is the smallest allowable for SA teststands. The most common SA test stand has a two section accumulator: a Test Gas Reservoir anda Test Drum.

The design pressure of the test drum and/or accumulator determines the pressure limits of reliefvalves that can be tested on the test stand. The design pressure of the test stand must be at least10% (and should be 15% to 20%) higher than the maximum set pressure of the relief valves to betested. The test flange mounting assembly welded on the test drum often establishes this designpressure limit.




Test Flange Mounting Assembly (Test Flange)

The relief valve being tested is mounted on the test flange. Test flanges are designed to mountflange adapters so that several relief valve sizes can be tested on one basic test flange.

Test flanges are usually welded onto the test drum of a standard SA test stand. In turn each testflange can mount several adaptor flanges, thereby, allowing a wide variety of relief valves to betested on one test stand.

Test Gage/s

The function of the test gage is to show the pressure under the relief valve disk. When thepressure under the disk equals the relief valve set pressure the relief valve should open. For reliefvalves in gas service, relief valve opening is accompanied by a resounding popping noise. Forrelief valves in liquid service, relief valve opening is determined when the stem reaches full lift.

Test gage requirements are outlined SAEP-1132, section 2.3. In general: test gage range shall bebetween 1.25 and 2.0 times the relief valve CDTP, scale markings shall be in the samemeasurement units as those of the relief valve set pressure, and test gages shall have evidence ofcalibration testing within three months of use on the test stand.

Interconnecting Piping And Valves

Valves mounted in the test stand interconnecting piping are used to manage the flow of fluidthrough the test stand. It must be understood that the rate of pressure rise beneath the relief valvedisk is crucial to the reliability of a test. Proper pressure rise rates for testing are listed in themanufacturer’s maintenance manual for the relief valve.

The above list of components is a generalized description based on a standard SA 'Test Facility'.A variety of commercial relief valve test stand are available with more advanced features such ashydraulically operated, automatic clamping, variable size test flange mounting assemblies, anddigital test gages. Some relief valve test stands have one quick disconnect pressure connection fora test gage rather than manifolded gages as shown in Figure 2. However, the basic function of thetest stand, regardless of enhancements, is to control pressure into the inlet of a relief valveundergoing test, and display that pressure throughout the test. If the test relief valve pops (or'opens' when liquid relief valves are tested) at the CDTP then the test is successful; otherwise, therelief valve must be adjusted then tested again until a successful test is completed.




Set Pressure Test

The shop QA manual regulates set pressure testing procedures. These procedures are based onthe test stand/s and other equipment available for testing and maintenance. In the absence of asample manual only information of a general nature can be presented in this section.

Cold Differential Test Pressure

CDTP is defined in API RP-520, Part I, 6th Ed. March 1993, page 2, paragraph 1.2.3.2.2 as:"The 'cold differential test pressure' is the pressure at which the pressure relief valve is adjusted toopen on the test stand. The cold differential test pressure includes corrections for the serviceconditions of back pressure or temperature or both."

Back pressure is a function of relief valve installation and must be determined by the specifyingengineer. The value for Back pressure listed on the relief valve ISS was determined fromengineering data when the relief valve was specified.

Temperature correction is a function of the expansion (or contraction) of parts within the reliefvalve. A temperature correction factor for the relief valve must be supplied by the relief valvemanufacturer, and must also be listed on the relief valve ISS by the specifying engineer.

CDTP = (Set Pressure) - (Maximum Superimposed Back Pressure + Pressure Adjustment forTemperature)

Maximum superimposed back pressure only applies to conventional non-bellows valves only(refer to ADP-J-600, 16 MAR 88, page 4, paragraph 2.12).

Note again that CDTP is listed for every relief valve on MWO form 891-5/-1 MWO, and can alsobe found in the relief valve Master File in the Shop.

The final set pressure testing relating CDTP to test stand testing is outlined in SAEP and copiedbelow.

SAEP-319, PAGES 13 & 14 EXCERPTS:

7.14 Final Set Pressure, CDTP Test.

7.14.1 The final CDTP set pressure shall be conducted on an approved test bench thatmeets the requirements of SAEP-1132, and using an approved procedure (partof the QA Manual) as defined in SAEP-1132, Section 3 and 4.




7.14.2 The set pressure tolerance shall conform to Table I of SAEP-1132, for springand pilot operated relief valves. Tank breather and pressure/vacuum reliefvalve tolerances shall conform to manufacturers guidelines.

7.14.3 The cold differential set pressure, CDTP, shall be temperature compensated asrequired by the manufacturer temperature charts based on normal operatingtemperature.

7.14.4 The cold differential pressure shall also be adjusted to compensate for any backpressure when a valve is installed in a closed relief system.

7.14.5 Pilot operated valves may be adjusted separately, however, the final test shallbe with the pilot and the main valves connected and tested together.

7.15 Final Seat Leak Test

7.15.1 The final seat leak test shall be conducted immediately after the final pressuresetting is achieved using the procedure described in SAEP-1132.

Functional Test

The shop QA Manual and the manufacturer’s maintenance manual for the relief valve being testedregulates Functional testing. Information presented below consists of generalities from SAEP-1132, and procedures copied from older relief valve maintenance manuals. Note again, that theoperation of a shop test stand is a procedure included in the shop QA manual. Leakage rates andother relief valve test tolerances are based on the specification and purchase data for that reliefvalve as reflected in the relief valve manuals; NOT, on revised SA, ASME, or API publicationsUNLESS these revision issues are addressed in the shop QA Manual as alterations to proceduresin the manufacturers manuals for the relief valve.

Functional testing begins with adjustments to the relief valve which allow further tests to beconducted. Oftentimes the first adjustments are to the adjustment ring/s (Blowdown and/orNozzle) which are accessed through the relief valve body after the Adjustment Ring Pin/s havebeen removed.

Excerpts below are copied from a Consolidated, Maxiflow maintenance manual and describe theprocedure for setting various adjustment rings while testing this valve:

Important Note: Some relief valves require a Lift Restrictor to limit disk travel during testing.Always check the relief valve manufacturers manual before mounting the relief valve on the teststand, and install a Lift Restrictor if required.




A general functional test procedure for using a test stand is outlined in SAEP-1132 and is copiedbelow. The test stand procedure references the schematic diagram on Figure 1.SAEP-1132, PAGES 6-8 EXCERPTS:

4. TEST STAND OPERATION

4.1 A test stand operating procedure shall be prepared and included in the reliefvalve Shop QA Manual. The procedure shall include safety requirements suchas eye and ear protection, safe tool operation, and installation of aircompressor filters. Refer to the testing requirements of SAEP-319, and reliefvalve manufacturer repair manuals to prepare a complete procedure.

4.2 A Certified Relief Valve Technician, as defined by SAEP-1134, shall operatethe Test Stand or be present.

4.3 Relief valves in liquid service shall be tested with liquids only, however, theymay be LEAK tested with gases (air or nitrogen).

4.4 Relief valves in vapor, air, gas, or a combination of liquid and gas service shallonly be tested with air.

4.5 Relief valves in boiler steam service may have the initial pop pressure set in theTest Shop using air, but the final pressure and blowdown setting shall be madewith steam, on the boiler using an approved In-place Procedure, as defined inSAEP-319 Section 10.

4.6 The following is an example instruction for testing a gas service springactuated relief valve on the typical relief valve Test Stand illustrated in Figure Iof this SAEP.

4.6.1 Before using the relief valve test stand eliminate loose particles in the systemby air blowing. This is done by closing valves V4 and V5, open valve V2 andV6, and to alternately open and close valve V1 until no particles are seen.Close test nozzle valve (V2) after flushing.

4.6.2 Testing begins with mounting the relief valve to the test nozzle flange.

4.6.3 Attach noise suppression line to relief valve outlet.

4.6.4 Open test nozzle valve (V2) and close the bleed valve.

4.6.5 Open the pressure gauge valve for the appropriate pressure range, refer toparagraph 2.3.1. Close all other pressure gauge isolation valves.




4.6.6 Increase pressure in test drum to 90 per cent of cold differential test pressure(CDTP) by opening valve V1. WARN Shop personnel of high noise level test.

4.6.7 Close valve V1 and use small bypass valve V8 to increase pressure smoothlyand continuously until the relief valve pops or CDTP tolerance is reached;BUT NEVER HIGHER THAN 10% OVER THE CDTP.

4.6.8 Close valve V8 and record pop pressure / results. Compare to allowabletolerances, shown in Table 1 of this Instruction.

4.6.9 Based on test results and Work Order, either disassemble, accept, rework orreadjust the relief valve. Perform a final verification test. Proceed with the leaktesting; see Section 5 for a representative procedure.

4.6.10 Remove the relief valve when testing is completed by first closing test nozzlevalve (V2).

4.6.11 Reduce stand pressure to 75% of the CDTP of the next valve.

4.6.12 Open bleed valve on test nozzle valve (V2) outlet and release pressure undertested relief valve.

4.6.13 Remove tested relief valve and install next valve to be tested. Go to operation4.6.1 for next test.

4.6.14 After ALL testing is complete, shut in the test stand by blowing down thedrum through valve V6. After verifying there is no pressure in the drum, closethe test gauge valve that was in use.

4.6.15 While the test stand is not in use, close valves V1, V2, V4, V5 and V8. Openvalve V6 or designate one valve that remains open when the test stand is not inuse.




SAEP-1132, PAGE 14 EXCERPT:

TABLE 1

Tolerances For Set Pressures Of relief valves(In English Units to conform to ASME Code requirements)

Set Pressure (CDTP) POP Pressure OK if0 to 100 psi (690 kPa) +/- 2 psig101 to 110 psi (760 kPa) +/- 3 psig (21 kPa)111 to 150 psi (1035 kPa) +/- 4 psig (28 kPa)151 to 199 psi (1780) kPa) +/- 5 psig (35 kPa)over 200 psi +/- 3 psig for every hundred psig

Steam Safety Valves:

Set Pressure (CDTP) POP pressure OK if0 to 70 psi(485 kPa) +/- 2 psi (16 kPa)71 to 300psi(2070 kPa) +/- 3%301 to 1000psi(6900 kPa) +/- 10 psi (69 kPa)over 1000psi +/-- 1%

NOTES: 1. Never conduct a test higher than 10% over the CDTP.

2. Never Conduct A Test Above The Test Stand MAWP.

SAEP-1132 Section 5 PAGES 8,9 EXCERPTS:

5. SEAT LEAKAGE TESTING

5.1 Leak testing is mandatory, and is conducted as required in SAEP-319.Leakage is measured through the seat to disk seal while the relief valve is at90% of CDTP. The test is conducted on the relief valve test stand.

5.2 The seat leakage test shall be conducted in accordance with API Standard 527.

5.3 Attach the special flange and water bubbler (it shall be designed with a ruptureseal that will vent full flow in the event the relief valve should open), as perFigure II, and seal all other relief valve body outlet or vents.

5.4 Hold 90% of CDTP for the required test period as follows:

5.4.1 One minute for 0.5" to 2" relief valve inlet size




5.4.2 Two minutes for 2.5" to 4" relief valve inlet size

5.4.3 Five minutes for all other larger inlets sizes

5.5 Compare BUBBLES PER MINUTE leakage rate to the acceptance criteria, asfollows:

5.5.1 Appendix Table II for relief valves with CDTP up to 1000 psig

5.5.2 Appendix Table III for relief valves with CDTP over 1000 psig.

5.6 When the relief valve body can not be sealed for the API 527 test method(such as an open bonnet relief valve design) then use the Half Gasket DamLeak Test Method.

5.6.1 Cover the lower half of the outlet flange with a half gasket or a fabricateddevice that allows the body cavity to be partially filled with water.

5.6.2 Fill the body cavity with water to cover the seating joint.

5.6.3 Raise the test bench pressure to 90% of the CDTP set pressure and look forevidence of bubbling from the seating joint. Use a mirror to observe theactivity; NEVER LOOK DIRECTLY INTO A relief valve OUTLET WHILEIT IS UNDER PRESSURE. No bubbles are acceptable with this method.

5.7 For small screwed relief valves, attach an elbow on the outlet, and fill the bodycavity and the elbow with water.

5.7.1 Raise the test bench pressure to 90% of the CDTP set pressure and look forevidence of bubbling at the open elbow. NEVER LOOK DIRECTLY INTOthe elbow WHILE IT IS UNDER PRESSURE. No bubbles are acceptablewith this method.





TABLE II

Leakage Rates For Safety Relief Valves WithSet Pressures To 1000 PSIG (6900 kPa)

TypeOf Valve

Manufacturer'sOrifice Size

StandardBubblesPer Min.

StandardCubic Ft.Per 24hrs

CubicMeters

Per 24 Hrs.Conventional F & smaller 40 0.60 0.017

G & larger 20 0.30 0.0085Balanced F & smaller 50 0.75 0.021bellows G & larger 30 0.45 0.017

34-SAMSS-611, 22 NOV 92, PAGE 2 EXCERPT:

1.6 Orifice Areas and Designations (Replacement)

The orifice areas shown on the Specification Sheet(s) Form 8020-611-ENGLines 50 and 51 are the calculated required area and the selected standard area,respectively.

The standard orifice areas and their corresponding letter designations are:

Sq cm (Sq in) Sq cm (Sq in)0.710 (0.110) - D 18.41 (2.853) - L1.26 (0.196) - E 23.2 (3.60) - M1.98 (0.307) - F 28.0 (4.34) - N3.25 (0.503) - G 41.16 (6.38) - P5.06 (0.785) - H 71.29 (11.05) - Q8.303 (1.287) - J 103.0 (16.00) - R11.86 (1.838) - K 168.0 (26.00) - T

Observe the nameplate copied on page 16 above, and note that it is from a PSV in steam service(SAT means the temperature of saturated steam at OP and MAWP (2500psig in this case).Observe also that the BORE DIA is 2.250. From the table in 1.6 (34-SAMSS-611) above that thebore is larger than a 'G' orifice.

However, the set pressure is greater than 1000psig (SAEP-1132 Table III), Table III below mustbe used to determine an acceptable leak rate for this valve PROVIDING THAT THE TABLELEAK RATE VALUE EXCEEDS THE MANUFACTURERS CERTIFIED LEAK RATEWHEN THE VALVE WAS PURCHASED.




It is important to review two additional functional tests addressed by SAEP-319

SAEP-319 PAGES 13 & 14 EXCERPTS:

7.12 RV Bellows Test

7.12.1 Leak test bellows to verify that the bellows sealing joint is 100% effective andthe bellows is not leaking.

7.12.1.1 A test shall be conducted by pressurizing one side of the bellows to 26 psig(138 kPa) or 25 percent of CDTP, Cold Differential Test Pressure (i.e. thepressure at which the relief valve is adjusted to open on the test stand) whichever is smaller. Over pressure can damage the bellows.

7.12.1.2 Check the non-pressurised side of the bellows using a method that is sensitiveto low volume flow. An apparatus similar to the seat leak test is recommendedso that all possible escaping air is directed out through a tube that issubmerged in water to detect bubbles.

7.12.2 An in-place test procedure is acceptable providing it is prepared and approvedas described in SAEP-319 Section 10.

7.13 RV Sealed Bonnet Leak Test.

7.13.1 RVs that are intended to have sealed bonnets and body joints and connected toclosed discharge systems shall be tested for tightness of the bonnet and bodyjoints to assure that NO-discharge gases or liquids escape to atmosphere.

Per an approved test procedure, part of the QA Manual, shall be conducted byapplying a 20-25 psig regulated air pressure to the relief valve body and bonnetcavity. There should be no evidence of leakage at any body joint. A soap testshould be conducted to ensure the integrity of the body joints.

7.17 Pilot Operated Relief Valve Testing

The T&I requirements are the same as spring actuated RVs. Pilot relief valvesshould be pressure tested as a complete assembly when possible. Blowdown isindependently adjusted in the pilot valve, and the setting procedure should bedone as recommended in the manufacturer's maintenance manual. Refer tomanufacturer maintenance manuals when disassembling and assembling pilotrelief valves. Soft goods should be changed as a preventive maintenancemeasure. Pilot control parts have very critical dimensions and surface finishes;replacement is recommended rather than reconditioning, when they are founddamaged.




Note again the relationship between Inspection Procedures related to T&I and maintenance andshop QA procedures, and manufacturers manuals. The shop QA manual must outline SaudiAramco maintenance policy when there are conflicts between official documents and procedures.




IN-PLACE TESTING

In-place testing, as the name implies, means that the relief valve is tested while mounted on itsprotected equipment. relief valves used for power boiler equipment shall be tested in-place forfinal set pressure and blowdown adjustments. Refer again to the relief valve name plate in Figure5, and note that the temperature of the relief valve will be the temperature of saturated steam at2500 psig, or approximately 670°F (refer to Crane, TP-410, page A-15). While the CDTPsupplied by the manufacturer would allow preliminary setting of the relief valve on the test stand,the National Board Of Boiler and Pressure Vessel Inspectors (National Board) does not considertest bench set point using CDTP data reliable for power boiler equipment protection.

However, in-place testing of relief valves is also dictated by economic factors based on whichtesting procedure is more cost effective. In-place testing requires test equipment to be moved tothe relief valve location. In some cases, as with power boiler equipment relief valves, processpressure is used to pop the relief valve under test, and check for leaks. In these cases theequipment is not available for plant operations until the relief valve has successfully passed thetests. In most cases other than power boiler relief valves, bottled gas is used for testing reliefvalves in-place, and the spare relief valve allows the equipment to continue operating. In all casesof in-place testing an exact test procedure is outlined in the shop QA manual and manufacturersmaintenance manual for the relief valve.

Reasons for In-Place Testing

Reasons for in-place testing are listed in SAEP-1132 Pages 16 and 17, as quoted below:

10.1 In-place relief valve T&I shall be approved when it is feasible and safe toadjust a relief valve on line, and the relief valve has satisfied the disassemblyrequirements, as required in paragraph SAEP-1132 7.9. An in-place testshould be limited to service conditions that are clean, sweet, and non-corrosive, such as LPG, lube oil, and steam.

10.1.1 Steam boiler safety valves shall be tested in-place for final set pressure andblowdown adjustment as required by ASME Section I.

Documentation requirements are likewise covered in the Inspection SAEPs:

10.2 The in-place testing is initiated by a 981-1 MWO that is approved by theOperating Superintendent; who writes "Approved for in-place test", and signsnext to the relief valve.




10.3 If the relief valve was inspected in the shop and is set in-place (this is requiredfor boiler steam relief valves) then the Relief Valve Maintenance Report, form3750, shall follow the relief valve into the field, and the Test Report finalpressure setting shall only be reported by the relief valve Technician whoperforms the in-place test. Only one Relief Valve Maintenance Report, form3750 is permitted per relief valve T&I.

10.4 An approved step-by-step Written Procedure is required. It shall be preparedby the local Operations Engineering Unit, and approved as follows:

10.4.1 The procedure is locally approved by the Superintendent of Operations,Inspection Unit Supervisor, Operations Engineering Unit Supervisor, and theArea Loss Prevention Superintendent. Also, the procedure activity iscontingent upon field witnessing by the local Operations Inspection Unit.

10.4.2 The procedure is then submitted to the Manager, Inspection Department, DH,for review and approval.

10.4.3 Final approval is contingent upon concurrence from P&CSD.

10.5 The procedure shall have provisions for:

10.5.1 Demonstrating full lift, and accuracy of adjustments.

10.5.2 Leakage testing instructions and criteria. The manufacturer's test procedure isadequate for boiler steam valves.

10.5.3 Clearly defined responsibilities.

10.5.4 Personnel safety precautions such as fresh air breathing equipment for toxicservices, hearing protection, discharge considerations, and other precautionsdetermined to be necessary.

10.5.5 Isolation of the relief valves and vessel pressure control during the test shall bewell defined.

10.5.6 Provisions and criteria for shop test and/or repair shall be made if the in-placetest or adjustments are not successful.




10.5.7 Description of the necessary tools and equipment that must be present beforethe test begins. While T&I and maintenance forms are the same as those usedin shop testing of RVs, in-place testing requires coordination and procedureapproval from operations and loss prevention management to insure the safetyof personnel and plant equipment. It is also cost effective to schedule in-placerelief valve testing to coincide with equipment maintenance schedules,especially when process fluid is used as test media, as in power boiler reliefvalve testing.

Set Pressure Test

When process media is used for in-place relief valve testing, the equipment pressure is raised tothe MAWP each time the relief valve is tested. If the relief valve is set too high the equipment issubjected to some overpressure up to the limit allowed by the test procedure. (A safeoverpressure limit approved by operations engineering is part of the test procedure.)

One way to avoid equipment overpressurization is to use a direct spring assist device on the reliefvalve. These devices allow relief valve testing at pressures lower than the valve set pressure byproviding a precise and repeatable force upward on the relief valve stem. When set properly theyconvert this force to pressure and record an equivalent test pressure when the valve pops.Although direct spring assist devices are not part of Module 6, the requirements for using themare quoted SAEP-1132 below.


6. SPECIALTY RELIEF VALVE TESTING DEVICES

6.1 Specialized relief valve testing devices, such as direct spring assist units, shallbe approved by ASME, the Inspection Department, CSD, and concurred withby Loss Prevention prior to using the equipment.

6.2 A direct spring assist device should incorporate precise, accurate andrepeatable pressure recording, as a minimum.

6.3 An approved Written Operating Procedure shall be developed by the User'sEngineering Unit that includes calibration details, limitations, operator training,and tolerance requirements. Approval shall be required by the Manager of theInspection Department, Instrumentation Engineering of CSD, and concurrencefrom Loss Prevention.




The actual set pressure test is conducted following the approved in-place testing procedure, thetest procedure outlined in the shop QA manual, and the set pressure methodology included in therelief valve manufacturers manual for the relief valve. Tolerances used to identify acceptable testresults are the same as those list for Shop Testing above. In the case of the representative steamrelief valve nameplate, a successful set pressure test would be a pop at 2500 psig +/- 1% (refer toTable 1 above). If this relief valve were a Maxiflow, the manufacturers procedure for adjustingthe set pressure and blowdown is copied above.

Functional Test

In-place functional testing is conducted according to agreed procedures, the shop QA manual andmanufacturers maintenance manual directives. Generalized functional testing in-place will followprocedures outlined above in section on Shop Testing. However, the order of testing should beconsidered, particularity if process media is used for testing.

If the relief valve has a lifting lever bring the process pressure up to 80% of set pressure and liftthe disk from the seat using the lever. If the disk is bound to the seat the relief valve must bedisassembled and checked. Therefore, the equipment will not be stressed by high pressure.

Leak test the relief valve at 90% of set pressure next (or first if no lifting lever test is conducted).If the relief valve fails the leak test it must be disassembled and inspected. Again the equipmentwill not be unduly stressed.

Finally 'pop' test the relief valve as outlined above, and after a successful set pressure test conducta final leak test the relief valve. Complete form 3750-ENG and follow normal administrativeprocedures.