Outlet Piping - Baker Hughes Consolidated 19000 Series Instruction Manual

XI. Recommended Installation Practices (Contd.)
Vibrations in the inlet piping systems may cause valve seat
leakage and/or fatigue failure. These vibrations may cause
the disc seat to slide back and forth across the base seat
and may result in damage to the seating surfaces. Also,
vibration may cause separation of the seating surfaces and
premature wear to valve parts. High-frequency vibrations
are more detrimental to SRV tightness than low-frequency
vibrations. This effect can be minimized by providing a larger
difference between the operating pressure of the system
and the set pressure of the valve, particularly under high
frequency conditions.
Temperature changes in the discharge piping may be
caused by fluid flow in from the discharge of the valve or by
prolonged exposure to the sun or heat radiated from nearby
equipment. A change in the discharge piping temperature will
cause a change in the length of the piping, which may cause
stresses to be transmitted to the
SRV and its inlet piping. Proper
support, anchoring or provision for
flexibility of the discharge piping
can prevent stresses caused by
thermal changes. Do not use fixed
supports.
C. Outlet Piping
Alignment of the internal parts of
the SRV is important to ensure
proper operation (see Figure
8). Although the valve body
will withstand a considerable
mechanical load, unsupported
discharge piping consisting of
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The pressure drop (P.D.) between the source of pressure in the protected equipment and
the pressure relief valve inlet is not to exceed 3 percent of the valve set pressure.
Figure 7: Pressure Drop on the Inlet Piping
Vessel
For a closed system, always keep piping strains isolated from the
Pressure Relief Valve, regardless of process operation and temperature.
more than a companion flange long-radius elbow, and a
short vertical pipe is not recommended. Use spring supports
to connect outlet piping to prevent thermal expansion from
creating strains on the valve. The discharge piping should be
designed to allow for vessel expansion as well as expansion
of the discharge pipe itself. This is particularly important on
long distance lines.
A continual oscillation of the discharge piping (wind loads)
may induce stress distortion in the valve body. The resultant
movement of the valve's internal parts may cause leakage.
Where possible, use properly supported drainage piping to
prevent the collection of water or corrosive liquid in the valve
body.
When two or more valves are piped to discharge into a
common header, the built-up backpressure resulting from
Cap may be
required for weather
protection
Long-Radius
Elbow
Figure 8: Outlet Piping Considerations
Consolidated 19000 Series Safety Relief Valve Instruction Manual
Vessel
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