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During commissioning the opening angle of the valve should be at least 15 degrees. This is to reduce the
effect of any pressure shocks on the valve.
Figure 25. If the opening angle is small, it is
recommended to perform flushing before
closing the valve
4.9 Commissioning
Exceeding the permitted values marked on the
valve may damage the valve and, in the worst
case, cause uncontrolled venting of the pres-
sure. This leads to equipment damage and
possibly also to personal injuries.
· The greatest permitted test pressure against
a closed valve is 1.1 x PN (PN = valve’s
max. trim ΔP). When carrying out a pipeline
pressure test (1.5 x PN), the valve must be
fully open. The tightness of the valve can be
ensured after this.
· If the stem is equipped with graphite packing
(BFC/BRC models), the tightness of the
packing should be checked. If required,
the graphite packings are tightened with the
hexagonal nuts until they no longer leak.
Do not over-tighten the packings as this
increases the valve torque.
4.10 Pressure test
NOTE:
It is recommended to perform the
flushing also before closing the
valve after it has been used for
control purposes so that the
opening angle has been small
(10° or less), see Figure 25.