26 | BHGE
© 2018 Baker Hughes, a GE company. All rights reserved.
1. Due to large capacity of the main valve, it is impossible
to adjust the pilot and main valve as an assembly unless
on an actual installation. To obtain a valve setting
on other than an actual installation, the pilot can be
removed from the main valve and adjusted on a small
test facility complying with the following requirements.
Reference Figures 20 and 21.
a. The pressure source or the test header must have
a minimum capacity of 6 ft
3
(170 m
3
). Header
mounting flange should be 4”-300# (101.6 mm -
20.4 barg) RF ASA flange.
b. The test fixture indicated in Figure 20 should be
equipped with a 4”-300# (101.6 mm - 20.4 barg) RF
ASA flange on the lower end and have appropriate
machining and drilling on the top end to match the
pilot flange (BHGE Part No. 4130901).
c. The test set up should be equipped with P
1
and P
2
pressure gauges as indicated in Figure 20. The P
1
gauge will sense inlet pressure and P
2
will sense
pressure equivalent to that back of the main valve
disc when the main valve is open.
2. The following procedure should be used for testing
the pilot.
a. Install pilot valve with sensing unit. Lower flange
and upper flange gasket on test fixture.
b. Pressurize system and note pop pressure
indicated by P
1
gauge. Adjust set pressure by
loosening compression screw locknut and rotating
compression screw clockwise (increase set point) or
counterclockwise (decrease set point) until proper
set pressure is established. Tighten compression
screw locknut.
c. Adjust blowdown by removing adjusting ring pin
and rotating adjusting ring clockwise (decrease
blowdown)
or
counterclockwise
(increase
blowdown) until proper value is established.
Blowdown is intentionally set for 10-12% of set
pressure at factory before installing on the main
valve. Tighten adjusting ring pin.
d. Pop pilot five times to ensure accurate settings
noting P
2
pressure at each pop. P
2
pressure should
drop to approximately 58% of P
1
.
e. Install lifting lever and cap on pilot. Bring system
pressure up to just below the pilot set point and lift
lever on pilot. Note that P
2
does drop to approximately
the same value indicated in Step d.
f. Check pilot for leakage. Bring the inlet pressure of
the valve up to 94% of set pressure. Pass a cold
rod across the outlet of the pilot. Any moisture
occurring on the rod indicates valve leakage.
g. Test of main valve and pilot assembly:
(i) Install pilot back on main valve.
(ii) Upon pressurizing the system, leakage around
main valve joints is permissible for approximately
one hour till the valve is uniformly heated.
(iii) Increase system pressure until pilot opens at
set point. Continue to overpressure until main
valve opens.
(iv) Check valve for leakage with system pressure at
90% of set.
CAUTION
Do not expose any part of the human body to the
discharge side of either the pilot or main valve. When
testing for leakage, stand 90° to the side of the outlet
discharge. In this position it is safe to pass a metal rod
downward across the outlet.
h. All external adjustments to the valve should be
sealed in accordance with ASME Code Section VIII
requirements.
XIX. Testing
Do not Stand or place
hand in front of valve
discharge flange if valve
is under pressure.
