Consolidated 1900/P Series Safety Valves Instruction Manual
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© 2020 Baker Hughes Company. All rights reserved.
XVI. Setting and Testing
Read and follow Safety Alerts on Section II. For Valve
Terminology see Section V.
Gauges used in valve setting must be kept calibrated in
accordance with applicable codes and standards.
Test Medium
Steam Internals valves shall be tested on saturated steam
as required by the ASME Code. The test medium must be
clean. Before mounting the valve on the test stand, remove
all dirt, etc. from the test receiver nozzle (valve inlet piping).
Set Pressure (Opening Pressure)
Set Pressure is dependent on spring tension which is
controlled by an adjusting screw located on top of the valve.
For accurate valve setting, pressure increases must be a
slow but uniform rate, but rapid enough to cause the valve to
open.
Table 9: ASME Code Section I
Set Pressure Range
Tolerance
psig
barg
15 to 70
1.03 to 4.83
± 2 psig (± 0.14 barg)
71 to 300
4.89 to 20.68
±3 percent of set
301 to 1000
20.75 to 68.95
± 10 psig (0.69 barg)
1000 & Greater 68.95 & Greater
± 1 percent of set
Table 10: ASME Code Section VIII
Set Pressure
Tolerance
psig
barg
0 to 70
0 to 4.83
± 2 psig (± 0.14 barg)
Over 70
Over 4.83
± 3 percent
A. Setting the Valve
Hold the spindle with Vise-Grip
®
pliers and set the valve
to the required set pressure by turning the adjusting screw
clockwise to increase the set pressure - counter-clockwise
to decrease the set pressure - then lock the adjusting screw
lock nut using two wrenches. Use one wrench to hold the
adjusting screw from moving while using the other wrench to
tighten the lock nut.
Open the valve only sufficient number of times to ensure that
the valve opens three times in succession at the desired set
pressure.
Simmer - If simmer causes erratic valve opening, refer to
Table
12, “Troubleshooting Guide”.
B. Back Pressure Compensation
When testing with steam, no temperature compensation is
required.
Conventional Valves: required to open against constant
back pressure. The back pressure must be subtracted from
the required set pressure to determine the test stand set
pressure.
Bellows Valve: all Steam Internals bellows are balanced by
design; therefore, they require no back pressure correction.
C. Blowdown (Reclosing
Pressure)
The Steam Internals safety valves are blowdown adjustable
by design, but do not attempt to adjust blowdown on the
stand because the test stand capacity may not be large
enough to permit doing so.
Be sure to lower the working pressure before making any
ring adjustment. This allows the spring force to keep the
valve closed otherwise the valve may pop during adjustment.
If the cap has a sealing plug, then use the gag supplied
finger-tight to prevent “popping” during ring adjustment.
The adjusting ring may be moved to improve action during
testing as the valve must operate smoothly without hang-up,
and it must reclose. In general, raising the ring increases
blowdown, and lowering the ring reduces blowdown.
To adjust blowdown:
1. Remove ring pin and gasket
2. Insert a small shank screwdriver through the ring pin hole
and engage a slot in the ring (see
Figure
20).
3. To increase blowdown (lower reseating pressure), the
adjusting ring must be raised by moving the notches
counter-clockwise.
4. To decrease blowdown (raise reseating pressure), the
adjusting ring must be lowered by moving the notches
clockwise.
After testing, place the ring in its original position or if
unknown, use Table
11 to relocate it. Be sure to remove the
