IM-P316-03 CTLS Issue 14
14
Excessive pressure loss at the inlet of a safety valve
when it operates will cause extremely rapid opening
and closing of the valve, observed as chattering or
hammering.
This may result in reduced capacity as well as
damage to seating faces and the other parts of
the valve.
When normal pressure is restored it is possible that
the valve will leak.
7.1 Solution
The safet y valve should be fitted 8-10 pipe diameters
downstream of any converging or diverging fittings
or bends, see Figure 6.
Inlet branches should be as Figure 7 or 8.
Fig. 6
Fig. 7 Fig. 8
a
Inlet area 'A'
is approximately twice that of area 'a'.
r
Radius 'r' not less than inlet diameter
8 - 10 pipe diameters downstream
of converging 'Y' fittings or bends.
7. Damage prevention