Valve Assembly Leak Tests - Emerson ANDERSON GREENWOOD 727 Installation And Maintenance Instructions Manual

ANDERSON GREENWOOD TYPE 727 DUAL PILOT MANIFOLD
INSTALLATION AND MAINTENANCE INSTRUCTIONS

9 VALVE ASSEMBLY LEAK TESTS

Air test (see Figure 11)
For the start of this test, ensure that the pilot
isolation hand valves identified as (1) and (2) on
both manifold ends are open and both manual
blowdown valves (3) on the front of the manifold
are closed (see Figure 12).
Internal leak test
Apply pressure to the inlet equal to 90% of
the set pressure. Perform the following:
1. Check for nozzle seal leakage by applying
leak test solution to the nozzle screws
and the nozzle body joint. No leakage is
permitted from this seal.
2. Perform a bubble rate leakage test at the
main valve outlet. Maximum observed valve
leakage should not exceed 20 bubbles in
one minute.
3. If excessive leakage is observed check the
main valve seat for leakage by applying leak
check fluid to the seat perimeter at the top
of the nozzle bore. If this is the source of
the leakage, disassembly of the valve and
relapping of the piston disc is required.
During reassembly replace the nozzle
screw Belleville washers, liner seal and
dipper tube port seal as these items are
not reusable.
4. Close both pilot isolation valves on the right
hand manifold end and open the right hand
pilot manual blowdown vent valve on the
front of the manifold to depressurize the
right hand pilot cavity. Check for tightness
of the isolation valve seats at the vent fitting
on the lower right corner of the manifold
face using a bubble tester. Repeat this
procedure for the left hand pilot.
5. Close both manual blowdown valves and
fully open at least one pilot isolation valve
on each manifold end to repressurize both
cartridge pilot cavities in preparation for
the next test series.
External leak test
1. After completing the internal leak test,
check all external joints, seals and hand
valve bonnets for external leakage by
applying leak test solution. Give particular
attention to the manifold/main valve cap
joint, the manifold port plugs and hand valve
bonnet connections. If leakage is observed
at the hand valve bonnet connection,
depressurize the valve and verify hand valve
bonnet torques as required. If torquing to
the correct value does not correct leakage,
then disassemble the faulty joint and inspect
for damaged seal or mating metal surfaces
and correct by replacing faulty component.
Do not attempt to seal leakages by over
torquing bolts or hand valve bonnets. If a
leak is observed between the main valve's
cap and body, between the manifold and cap
or around the manifold port plugs, contact
the factory.
2. After completing the above test then check
each cartridge pilot main wedge seal for
tightness with a bubble tester applied to
the manifold pilot vent fitting for each pilot.
No leakage should be observed (see note).
If leakage is observed, depressurize the
valve and, using a 2" wrench on each pilot
bushing, check that both pilot main wedge
seals are seated fully. Then repressurize the
valve and recheck leakage.
Note: for steam service valves – observed
air leakage at each vent should not exceed
the values determined from the pilot
performance test (see Section 7) for each
respective pilot seat.
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