Consolidated 2700 Series Safety Valve Instruction Manual
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© 2022 Baker Hughes Company. All rights reserved.
A. General Information
Upon completion of hydrostatic testing of the boiler, but
prior to placing the boiler in service,
ENSURE THAT THE HYDROSTATIC TEST PLUGS
ARE REMOVED FROM ALL VALVES.
All Consolidated Series 2700 Safety Valves are steam
tested at the factory to verify set pressure adjustability
and seat tightness. Every valve is set to have a clean
popping action and to reseat tightly. However, because
the boiler used in setting the valves has a small
capacity, compared to the capacities of Consolidated
safety valves, the valves are factory set with a long
blowdown to prevent chattering under initial startup
conditions. Final adjustments should be made on the
operating system with conditions similar to those that
will be realized under actual operating conditions.
Note:
Baker Hughes recommends full flow steam
testing upon initial startup.
Adjusting ring settings are initial adjustments only and
are not intended to be final adjustments.
The use of a Consolidated Hydroset Test Device or
EVT software can serve to establish set pressure
but cannot be used for verifying blowdown, lift,
etc. (For additional information, see Section X,
Recommended Installation Practices, of this manual).
It is recommended that the safety valves be tested and
adjusted with the boiler isolated.
Factors that can affect valve operation, and that should
be considered when initially setting a valve, are as
follows:
1. Ambient temperature near the valve and valve
temperature stabilization.
2. Line vibration.
3. Valve capacity versus rated flow through the line
the valve is mounted on.
4. Discharge stack or drain piping binding.
5. Flow-induced vibrations or pressure pulsations
set up by upstream bends. Valve inlet nozzle
configuration, or other internal piping configuration
problems.
6. High water level in the drum.
When the valves are subjected to working hydrostatic
tests not exceeding the set pressure of the low
set valve, valves may be gagged rather than
using hydrostatic test plugs. For higher pressures,
hydrostatic plugs should be used.
A common source of safety valve trouble is over-
gagging. During hydrostatic testing, and during safety
valve setting, gags should be applied only hand tight.
During setting, over gagging will also cause damage to
the seating surface and result in seat leakage.
The gag load applied should be only enough to ensure
that the valves do not lift at the expected overpressure.
During startup, gags should never be applied when the
boiler is cold. The spindle of the safety valve expands
considerably with the temperature increase. If it is not
free to expand with this temperature change, it may
become seriously overstressed and bent.
Except for hydrostatic tests, boiler pressure should be
brought up to within 80 percent of the pressure of the
low set valve before applying gags.
Tighten the gags of drum and superheater valves hand
tight.
When adjusting the ring positions of a valve, the valve
must be gagged to prevent accidental lifting and
personal danger.
If testing the set pressure of a valve, the other valves
in the system should also be gagged.
B. Application of Test Gags
(All Pressures)
1. Refer to Figure 17. Remove top lever pin and
top lever, then loosen the cap screw. Remove
the lever and cap assembly. The release nut is
fixed to the spindle by means of a cotter pin. Note
that the release nut does not quite engage top of
compression screw.
2. Center the test gag in the exposed end of the
spindle and hook the legs of gag under the sides
of the yoke.
Do not apply the gag load until the system steam
pressure is equal to 80 percent of the pressure to
which the low set valve is adjusted.
XV. Setting and Testing
