Saudi Aramco Standards
Saudi Aramco Standards
Saudi Aramco Standards
1 Scope
1.1. This Saudi Aramco Engineering Procedure (SAEP) defines the instructions and
requirements for using Relief Valve Test Stands (RVTS) during testing and
maintenance of Pressure Relief Devices (PRD) in Saudi Aramco operating
facilities.
1.2. This procedure applies to shop testing of all pressure relief devices defined in
SAEP-318.
1.3. RVs in Saudi Aramco operating facilities which are to be tested by third party
RV Shop shall be tested according to the requirements of this SAEP.
1.4. RVs which are on or a part of equipment owned and operated by Contractors
within Saudi Aramco Operating Units shall be tested and inspected in
accordance with this Procedure.
1.5. Buckling Pin and Surge Relief Valves which have an approved separate In-
Place Test Procedure as per SAEP-319 are excluded from this procedure.
2 Purpose
2.1 The test stand shall have a volume large enough to provide reliable RV
adjustment and pressure testing at the specified, Cold Differential Test Pressure
(CDTP) within the tolerances set by the applicable Code.
2.2 For gas service, a test stand must be able to cause a sharp pop of the RV for the
test to be valid. Simple opening and passing of air or nitrogen is not acceptable.
The gas service test stand design described in this Procedure is intended to
provide a sharp pop action with minimum altering of the blowdown ring
adjustment. However, the blowdown ring may be adjusted to assist in achieving
a valid pop action for the test. Upon these occasions it is essential that the
blowdown ring be returned to its original operating position upon completion of
the test.
2.3 The RV test stand shall provide sufficient capacity to adequately verify the
pressure at which the RV pops without damaging the valve trim. Insufficient
volume, poor pressure control, inaccurate gauges or contaminated test media
may cause unreliable testing and/or additional maintenance. Test stand design is
intended to produce a pop action, because a pre-simmer action is not the true
opening pressure of a gas service RV, by manufacturer's definition. This pre-
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Document Responsibility: Inspection Engineering Standards Committee SAEP-1132
Draft Date: 30 June 2014
Next Planned Update: 30 June 2019 Instructions for Using the Relief Valve Test Stand
simmer test method can result in a 10-15% difference in the actual popping
pressure. RV manufacturers have recommended that "lift restrictors" be used
for testing even with the Saudi Aramco test stand.
2.4 To ensure RVs remain in good physical condition and comply with all
requirements of this procedure for external condition as specified in Appendix
E.
2.5 To ensure roles and responsibilities for RV Testing and Maintenance are
outlined and auditable.
2.6 It is not the purpose of a Saudi Aramco test stand to adjust blowdown for boiler
valves because the test stand volume is too low. Blowdown adjustments shall be
made with an approved RV IN-PLACE Procedure. See SAEP-319.
3.1 Waivers
3.2 Deviations
4 Applicable Documents
The requirements contained in the following documents apply to the extent specified in
this procedure.
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Galling - A condition whereby excessive friction between high spots results in localized
welding with subsequent splitting and a further roughening of rubbing surfaces of one
or both of two mating parts.
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API 520-1 for the preliminary sizing equations. API 526 provides effective discharge
areas for a range of sizes in terms of letter designations, “D” through “T.”
Inlet Size - The nominal pipe size (NPS) of the relief device at the inlet connection,
unless otherwise designated.
Lift - The actual travel of the disk away from the closed position when a pressure-relief
valve is relieving.
Outlet size - The nominal pipe size (NPS) of the relief device at the discharge
connection, unless otherwise designated.
Accumulation - The pressure increase over the MAWP of the vessel allowed during
discharge through the pressure-relief device, expressed in pressure units or as a
percentage of MAWP or design pressure. Maximum allowable accumulations are
established by applicable codes for emergency, operating, and fire contingencies.
Design pressure - The design pressure of the vessel along with the design temperature
is used to determine the minimum permissible thickness or physical characteristic of
each vessel component, as determined by the vessel design rules. The design pressure is
selected by the user to provide a suitable margin above the most severe pressure
expected during normal operation at a coincident temperature. It is the pressure
specified on the purchase order. This pressure may be used in place of the MAWP in all
cases where the MAWP has not been established. The design pressure is equal to or less
than the MAWP.
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design pressure when the design rules are used only to calculate the minimum thickness
for each element and calculations are not made to determine the value of the MAWP.
Overpressure - The pressure increase over the set pressure of a pressure relief of a
relieving device allowed achieving rated flow. Overpressure is expressed in pressure
units or as a percentage of set pressure. It is the same as accumulation only when the
relieving device is set to open at the MAWP of the vessel.
Rated Relieving Capacity - The relieving capacity used as the basis for the application
of a pressure-relief device. This capacity is determined in accordance with the
applicable code or regulation and is provided by the manufacturer. NOTE the capacity
marked on the device is the rated capacity on steam, air, gas, or water as required by the
applicable code.
Stamped Relieving Capacity - The rated relieving capacity that appears on the device
nameplate and based on the rated relieving capacity determined at the specified set
pressure or burst pressure plus the allowable overpressure.
Blowdown - The difference between the set pressure and the closing pressure of a
pressure-relief valve, expressed as a percentage of the set pressure or in pressure units.
Burst Pressure - The burst pressure of a rupture disk at the specified temperature is the
value of the upstream static pressure minus the value of the downstream static pressure
just prior to when the disk bursts. When the downstream pressure is atmospheric, the
burst pressure is the upstream static gauge pressure.
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Burst-Pressure Tolerance
The variation around the marked burst pressure at the specified disk temperature in
which a rupture disk will burst.
Closing Pressure - The value of decreasing inlet static pressure at which the valve disc
reestablishes contact with the seat or at which lift becomes zero, as determined by
seeing, feeling or hearing.
Leak-Test Pressure - The specified inlet static pressure at which a seat leak test is
performed.
Manufacturing Design Range - The pressure range at which the rupture disk shall be
marked. Manufacturing design ranges are usually catalogued by the manufacturer as a
percentage of the specified burst pressure. Catalogued manufacturing ranges may be
modified by agreement between the user and the manufacturer.
Marked Burst Pressure Or Rated Burst Pressure - The marked burst pressure or
rated burst pressure of a rupture disk is the burst pressure established by tests for the
specified temperature and marked on the disk tag by the manufacturer. The marked
burst pressure may be any pressure within the manufacturing design range unless
otherwise specified by the customer.
The Marked Burst - pressure is applied to all the rupture disks of the same lot.
Opening Pressure - The value of increasing inlet static pressure whereby there is a
measurable lift of the disk or at which discharge of the fluid becomes continuous, as
determined by seeing, feeling or hearing.
Set Pressure - The inlet gauge pressure at which a pressure-relief valve is set to open
under service conditions.
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Simmer - The audible or visible escape of compressible fluid between the seat and disc,
which may occur at an inlet static pressure below the set pressure prior to opening.
Specified Burst Pressure - The specified burst pressure of a rupture disk is the burst
pressure specified by the user. The marked burst pressure may be greater than or less
than the specified burst pressure but shall be within the manufacturing design range.
The user is cautioned to consider manufacturing range, superimposed backpressure and
specified temperature when determining a specified burst pressure.
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or pop action. When the static inlet pressure reaches the set pressure, it will increase the
pressure upstream of the disk and overcome the spring force on the disk. Fluid will then
enter the huddling chamber, providing additional opening force. This will cause the disk
to lift and provide full opening at minimal overpressure. The closing pressure will be
less than the set pressure and will be reached after the blowdown phase is completed.
The spring of a safety valve is usually fully exposed outside of the valve bonnet to
protect it from degradation due to the temperature of the relieving medium. A typical
safety valve has a lifting lever for manual opening to ensure the freedom of the working
parts. Open bonnet safety valves are not pressure tight on the downstream side.
6 Instructions
d) As built drawings, Safety Instruction Sheet, and Design Data Form shall
be available and entered into the SAO drawing system by the User.
e) If a test drum is included in the RVTS design, the test drum shall have an
approved Equipment Inspection Schedules (EIS) per SAEP-20 with a
maximum of 60 months interval.
b) Gauges shall have scale markings in the same measurement units as those
of the RV set pressure shown on the. Conversions between units shall not
be made. The gauge scale definition shall be adequate to determine the
pressure tolerances.
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6.2.2 A Vacuum pump shall be included in the Test Facility where vacuum
type breather valves are maintained.
6.2.4 Adapter plates and special fixtures shall be readily available for
mounting and testing the various types of RVs being maintained.
6.2.5 The pilot of Pilot RVs may be adjusted using the gas test stand or a
specialized pilot test stand.
6.2.6 A single unit with capacity to test multiple services (gas and liquid) is
acceptable provided purging capacity is built in.
6.2.7 Accumulator tank size specification and other design specification shall
be adequate to prevent RV seat hammering.
6.2.9 Any modification to the original design of the RVTS shall include:
b) MOC document.
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6.3.8 Safety shatter resistant screen between the RV Test Technician and the
clamp bench installed.
6.3.9 An approved Equipment Inspection Schedule (EIS) exist for the RV Test
Stand.
6.3.11 Ensure visual and audible safety alarms in the RVTS are available.
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6.4.3 Minimum Spare parts for the test stand shall be maintained.
d) RV's in vapor, air, gas, or a combination of liquid and gas service shall
only be tested with gases (air or nitrogen).
e) RVs in boiler steam service may have the initial pop pressure set
in the Test Shop using air, but the final pressure and blow-down setting shall be
made with steam, on the boiler using an approved In-place Procedure, as defined
in SAEP-319 Section.
g) Before using the RV test stand eliminate loose particles in the system by
air blowing. These is done by closing valves V4 and V5, open valve V2 and
V6, and to alternately open and close valve V1 until no particles are visually
seen. Close test nozzle valve (V2) after flushing.
j) Open test nozzle valve (V2) and close the bleed valve.
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k) Open the pressure gauge valve for the appropriate pressure range.
n) by opening valve V1. WARN Shop personnel of high noise level test.
t) Open bleed valve on test nozzle valve (V2) outlet and release pressure
under tested RV.
w) After ALL testing is complete, shut in the test stand by blowing down
the drum through valve V6. After verifying there is no pressure in the drum,
close the test gauge valve that was in use.
x) While the test stand is not in use, close valves V1, V2, V4, V5 and V8.
Open valve V6 or designate one valve that remains open when the test stand is
not in use.
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6.6.2 The seat leakage test shall be conducted in accordance with API STD
527.
6.6.3 Attach the special flange and water bubbler (it shall be designed with a
rupture seal that will vent full flow in the event the RV should open), as per
Figure II, and seal all other RV body outlets or vents.
6.6.4 Hold 90% of CDTP for the required test period as follows:
Appendix Table III for RV's with CDTP over 1000 psig.
6.6.6 When the RV body can not be sealed for the API STD 527 test method
(such as an open bonnet RV design) then use the Half Gasket Dam Leak Test
Method.
Cover the lower half of the outlet flange with a half gasket or a
fabricated device that allows the body cavity to be partially filled with
water.
Fill the body cavity with water to cover the seating joint.
Raise the test bench pressure to 90% of the CDTP set pressure and look
for evidence of bubbling from the seating joint. Use a mirror to observe
the activity; NEVER LOOK DIRECTLY INTO A RV OUTLET
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6.6.7 For small screwed RVs, attach an elbow on the outlet, and fill the body
cavity and the elbow with water. Raise the test bench pressure to 90% of the
CDTP set pressure and look for evidence of bubbling at the open elbow. Never
look directly into the elbow while it is under pressure. No bubbles are
acceptable with this method.
6.6.8 The maximum test pressure for RVs tested in the RVTS shall be
specified and included in the Quality Assurance (QA).
6.6.9 Dryness procedure for RVs tested in liquid shall be available and
included in the Quality Assurance (QA).
6.8.1 Use a lift restrictor to limit the disk travel when momentum forces cause
hammering damage to the disk. Dresser Consolidated recommends 1900 Series
valves with orifice sizes D and greater be tested with lift restrictors. Crosby also
state that their valves should be tested with lift restrictors. Contact OID/ID,
Dhahran for fabrication and adjustment details.
6.8.2 Avoid testing with incorrect test equipment. Contact OID or Dhahran
Shops, Planning and Coordinating Unit, Dhahran, if assistance is needed in
locating a RV Shop with a larger capacity or specialized test equipment.
6.8.3 Steam boiler safety valves shall not have the blow down adjusted on a
test bench.
6.9.1 Specialized RV testing Devices, such as direct spring assist units, shall
be ASME stamped. Inspection Department and P&CSD approval is required and
concurrence by Loss Prevention prior to using the equipment.
6.9.2 A direct spring assist device should incorporate precise, accurate and
repeatable pressure recording, as a minimum.
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Revision Summary
30 June 2014 Revised the "Next Planned Update". Reaffirmed the contents of the document, and reissued
with no other changes as major revision.
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vent/drain
V4
bleed
valve
V1
V2 2"
2"
RV for more
vessel V8
V6
V6
drain
Figure I – Typical Safety Relief Valve Test Facility Using Air or Nitrogen as Test Medium
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blind/plate
pressure blowout
hole in plate
tube
water cup
Leak tester
for
screwed
connection
Figure II – API STD 527 Test Apparatus for RV Metal to Metal Seat Leak Testing
Attach the blind/plate to the RV outlet and seal all other body ports so that the only available
gas exit from a seat leak is through the water trap.
Use the half gasket leak test method if body ports can not be sealed. With this method, the
outlet is partially covered or an elbow is attached to permit filling of the body cavity with
water. Leaking seats will cause bubbles in water. With this method NO LEAKAGE IS
PERMITTED.
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vent
Dome pressure
indicator
Pilot valve
Exhaust vent
Support Blowdown
adjusment
Inlet supply
pressure indicator
Pressure supply
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Manometer
Vent
Pallet Access
T a n k B re a th e r
Vacuum Port
L o w P r e s s u r e S u p p ly
V a cuum S ource
Mount breather on test flange after disassembly, cleaning and repairs are complete.
1. Replace all soft goods, and restore seating surfaces.
2. Pallets should be checked for free movement before testing.
3. Verify that weighted pallets have not been altered. Apply the correct pressure, and verify pressure when
pallets opens.
4. Isolate pressure source, and apply vacuum. Verify vacuum pressure when pallet lifts.
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NOTES: 1. NEVER CONDUCT A TEST HIGHER THAN 10% OVER THE CDTP.
2. NEVER CONDUCT A TEST ABOVE THE TEST STAND MAWP.
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300
250
200
150
BUBBLES PER MINUTE, MAX.
100
90
80
ER
70
LL
A
SM
60
&
F"
."
IF
R
50
O
40
ER
G
R
LA
30
&
"
G
."
IF
R
O
20
1000 1500 2000 2500 3000 4000 5000 6000
(6.9) (10.3) (13.8) (17.2) (20.7) (27.6) (34.5) (41.4)
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APPENDIX A
Availability of the annual external inspection and preventive maintenance plan for
the test stand according to the manufacturer’s FAT Check and Test Plan checklist.
The following safety features of the test stand shall be included in the annual
external inspection check list:
Obtain the approved EIS for the RV Test Stand including the liquid and gas
reservoir tanks based on a maximum of 60 months inspection interval.
The RVs for protecting the test stand shall either be tracked in SAP or included
in the test stand preventive maintenance (PM) program.
Pressure gauges installed shall have the same units as the tested RVs at all times,
with a range of 1.25 to 2.0 times the RV Cold Differential Test Pressure (CDTP).
Pressure gauges shall be calibrated every 3 months.
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