With Sensing Ring Option; Functional Testing - GE Baker Hughes 2900-40 Series Maintenance Manual

XX. Setting and Testing (Cont.)
C. With Sensing Ring Option
(Figure 39)
Figure 39: with Optional Line Filter
Remote sensing is the standard pressure connection to the
pilot valve used on the 2900-40 Pilot Operated Safety Relief
Valve. However with the Sensing Ring Option, the pilot valve
pressure can be picked up just before the inlet of the main
valve.
The gaskets which are supplied by the customer are to be
inserted between the Valve Nozzle and the Sensing Ring and
between the Sensing Ring and the test system flange.
D. Functional Testing
ATTENTION!!
Filter in sensing tube to be removed if the following filter
options are utilized.
1. Repeat set point verification tests 3 times.
a. Inlet pressure ramp guidelines.
(i) When set pressure is below or equal to 750 psig
(51.7 barg), the inlet pressure ramp should not
exceed 0.5 psig (0.03 barg), per second, when test
pressure is within 90% of set pressure.
(ii) When set pressure is above 750 psig (51.7 barg),
the inlet pressure ramp should not exceed 1.0
psig (0.07 barg) per second, when test pressure is
within 90% of set pressure.
c. Drop system to 90% of set pressure between cycles.
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d. The 3 tests should be within the tolerances listed in
Table 15.
e. If blowdown is being checked, the following guidelines
are to be followed.
Note: blowdown can be set and checked on the main valve only if the
system can achieve 10% over pressure.
(i) 39PV model (gas/steam): less than or equal to 5%
or 3 psig (0.20 barg), whichever is greater.
(ii) 39PV model (liquid): between 7% and 4%. If set
pressure is less than 30 psig (2.1 barg), 3 psig (0.20
barg), or less.
Note: Customer requirements may note a variation to the standard
blowdown. Customers request takes priority.
CAUTION
Do not adjust blowdown, compression screw, or adjuster
while pilot is pressurized.
f. If adjustments are necessary, adjust Compression
Screw or Adjuster and retighten corresponding lock
nut. Starting position of adjuster shall be 8 turns.
Retest beginning at step 9.
2. Main valve equipped with metal seats and steam as the
test media.
a. Leak tightness shall be checked visually using a
black background. There shall be no visual or audible
leakage after the interior or the valve is allowed to dry
after popping. The leak test pressure shall be when
pressure is held at 4% below valve set pressure or 2
psig (0.14 barg), whichever is greater.
b. Increase pressure from 90% of set pressure to 4%
below set pressure or 2 psig (0.14 barg), whichever
is greater, and check all ports and connections for
leakage on Pilot and Main Valve.
c. Repair of valves which show leaks in backpressure
testing may be attempted by tightening the joint
involved to normal tightness, while the valve is in the
testing area. The valve is to be examined for cause of
failure, the cause corrected, and the test repeated.
d. To isolate leakage that may be coming from the pilot,
disconnect the pilot vent line (if applicable) from
the main base outlet and plug the main valve outlet
connection. If wet paper still bulges, then leakage is
occurring from main valve.
e. Leakage from main valve can come from either
the main valve seat, nozzle seal or dome seal. To
determine if the leakage is from either the main valve
seat or nozzle seal, the outlet must be filled to above
the seat line and checked for bubbles. If no bubbles
are present, then leakage is either coming from the
Consolidated 2900-40 Series POSRV Maintenance Manual | 51