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Baker Hughes
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5. When presetting is complete, remove the gag and
replace the cap and lifting lever assembly. Attach
a rope to the lever and stand by to hold the valve
open if necessary. Now the valve is ready to test.
6. Increase the boiler pressure at a rate not to
exceed 2 psig (0.14 barg) per second. Note and
record the pressure indicated on the pressure
gauge when the valve pops open. After the valve
pops open, reduce the fire in the boiler and lower
the pressure until the valve closes. Note and
record the pressure when the valve closes.
7. Determine if the valve popping point and reseating
point comply with the ASME requirements.
a. If the valve operation meets the appropriate
standard, raise the pressure in the boiler and
conduct two more verification test.
b. If in raising the boiler pressure, the valve does
not pop open within 3% overpressure (for
ASME Section I valves), or 10% overpressure
(for ASME Section VIII valves),
reduce the
fire in the boiler and pull the rope to open
the valve.
Release the rope and allow the
valve to close when the boiler pressure returns
to operating level. Allow the boiler to reduce
to approximately 85% of the set pressure.
Remove the cap and lifting lever assembly
from the valve, and turn the compression
screw lock nut counter-clockwise (as viewed
from the top of the valve) until it moves freely.
Reduce the compression in the spring by
turning the adjusting screw counter clockwise
one turn (as viewed from the top of the valve).
Replace the cap and lifting lever and retest the
Baker Hughes recommends that the maximum operating pressure never exeeds 94% of the set pressure
of the 1811 Series safety valve.
Cold Differential Test Pressure (CDTP): Add 0.5% of the set pressure for each 100°F of superheat above
saturated steam temperature.
Table 8
ASME Boiler and
Pressure Vessel
Code Section and
Symbol
CODE SYMBOL
STAMP
ASME Section I
Set Pressure Tolerance (The valve must
“POP” open within the range indicated
below.)
Blowdown Requirements
If valve set pressure is less than or equal to
70 psig (4.83 barg)
±2 psig (±0.14 barg)
After opening, the valve must reclose
within a range of 98% to 96%, however,
if the valve set pressure is 100 psig (6.89
barg) or less the valve must reclose
within a range of 2 to 4 psig (0.14 to 0.28
barg) below set pressure.
If valve set pressure is 71 psig (4.90 barg)
up to and including 300 psig (20.68 barg)
±3% of set pressure
If valve set pressure is 301 psig (20.75) up
to and including 1000 psig (68.75 barg)
±10 psig (±0.69 barg)
If valve set pressure is 1001(69.02 barg) or
greater
±1% of set pressure
CODE SYMBOL
STAMP
ASME Section VIII
If valve set pressure is less than or equal to
70 psig (4.83 barg)
±2 psig (±0.14 barg)
After opening the valve must reclose
before the system pressure returns to
normal operating pressure.
If valve set pressure is 71 psig (4.90 barg)
or greater
±3% of set pressure
XIV. Setting and Testing
V
UV
