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Baker Hughes
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E. Consolidated Hydroset Device/EVT
Software
Periodic tests may be required for verification of valve set
pressure. Both
the Consolidated Hydroset Test Device and EVT software provide for this
capability; however, set pressure is the only factor that can be verified.
Valves should be initially set using full system pressure (as outlined in
sections XIV.A. through XIV.C. of this manual). The Consolidated Hydroset
Test Device or EVT software is used for subsequent checks of set pressure.
Setting safety valves by the recommended method of lifting valves
under steam pressure presents a number of problems. In high-pressure
conventional boilers, superheater tubes may be damaged if the turbine is not
operating. Also, the expense of feed water, fuel and personnel involved is
considerable.
Although these problems cannot be eliminated entirely, they can be reduced
by using a hydraulic or electronic device that allows the set pressure to be
checked while the system pressure remains below the set pressure.
Accuracy of results obtained by the use of either of these devices depends
on several factors. First, friction must be reduced as a source of error so
that, for a given pressure, the Hydroset Test Device or the EVT software
repeatedly produces exactly the same lifting force. Second, gauge calibration
and vibration, in the effective seating area between valves of the same size
and type, will also affect accuracy. With well-calibrated gauges and valve
seats in good condition, accuracy on the order of ±1 percent of set pressure
may be expected. Upon request, Baker Hughes will provide pertinent
written material concerning the Consolidated Hydroset Test Device or EVT
software. This material specifies all required information necessary to ensure
proper usage of these devices.
F. Hydrostatic Test Plug Removal
F.1 General Information
Flanged inlet safety valves shipped without hydrostatic test plugs should be
removed from the boiler during hydrostatic tests and boiler nozzles blanked
off to prevent possible valve damage.
All welded inlet valves shipped are shipped with hydroplug (see Figure 18),
unless the customer specifically requests otherwise. All flanged inlet valves are
shipped without a hydroplug.
Valves shipped with hydroplug are identified by a red on white CAUTION
TAG, that is attached to the valve by wires extending through the drain hole
in the valve body (see Figure 18).
Hydrostatic test plugs must be removed prior to firing the boiler.
XV. Setting and Testing (Cont.)
Improper lift
adjustment may result
in severe personal
injury or death.
Do not disassemble
valve with pressure in
drum or header, as this
will result in severe
personal injury or death.
