Richter KSEA/F Series Safety Valves - Manual (Page 19)

Series KSEA/F
Page 19
9530-052-en Revision 03
TM 7128 Edition 05/2008
9.9.6 Seat tightness test with air
Pressure relief valves marked for gas or vapour
may be leakage tested with air.
According to API 527, the bubbles are led by a test
hose with an outside diameter of
7.9 mm (5/16”) and a wall thickness of 0.89 mm
(0.035”) in a container filled with water whereby the
test hose discharges 12.7 mm (0,5”) below the
surface of the water.
The tube end shall be cut square and smooth. The
tube shall be perpendicular to the surface of the
water.
Leakage test pressure for testing with air:
For set pressures greater than 3.45 barg (50 psig)
the leakage test pressure is 90 % of the set
pressure.
For set pressures equal or less 3.45 barg (50 psig)
the leakage test pressure is 0.344 barg (5 psig)
less than the set pressure.
9.7.7 Leakage test with air
Before the leakage test, the set pressure shall be
demonstrated and all valve body joints and fittings
should be checked with a suitable solution to
ensure that all joints are tight.
Before the bubble count, the test pressure shall be
applied for at least 1 minute for valve whose
nominal pipe size is 50 mm (2”) or smaller, 2
minutes for a valve whose nominal pipe size is 80
mm (3”) or 100 mm (4”).
The valve shall then be observed for leakage for at
least 1 minute.
9.9.8 Acceptance criteria (air)
For a soft seated valve, there shall be no leakage for
1 minute (0 bubbles pro minute).
9.9.9 Seat tightness test with water
Pressure relief valves marked for liquid service
shall be tested with water or other suitable liquid.
Leakage test pressure for testing with water:
For set pressures greater than 3.45 barg (50 psig)
the leakage test pressure is 90 % of the set
pressure.
For set pressures equal or less 3.45 barg (50 psig)
the leakage test pressure is 0.344 barg (5 psig)
less than the set pressure.
9.9.10 Leakage test with water
Before starting the seat tightness test the set
pressure shall be demonstrated, and the outlet
body bowl shall be filled with water, which shall be
allowed to stabilize with no visible flow from the
valve outlet.
The inlet pressure shall then be increased to the
test pressure. The valve shall then be observed for
1 minute at the test pressure.
9.9.11 Acceptance criteria (water)
For soft seated valves, there shall be no leakage for 1
minute.
9.9.12 Back pressure test
According to UG 136 (d)(3), valves constructed
with Low Pressure Bellows shall be tested with air
or nitrogen not to exceed a pressure of 15 psig.
Valves constructed with high pressure bellows
shall be tested with air or nitrogen at 30 psig or
otherwise stated by special customer requirement
not to exceed 45 psig. The special customer
requirement will be indicated on the Inspection
Sheet.
Back pressure tests will be performed by
pressurizing valve body with air or nitrogen through
outlet.
Leakage may be detected by applying soap
solution or leakage spray to valve body.
Note possible leakage at construction seams.
If leakage is detected, tighten applicable
construction bolting.
If leakage persists, disassemble valve, identify leak
point, repair or replace applicable components,
assemble and retest.