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XII. Recommended Installation Practices (Cont.)
temperatures.
Example: the condensed steam in the pilot and tubing
may become frozen.
3.
Applications where the process media is temperature
sensitive to thick formations.
Example: hydrocarbon applications where the possibility
of hydrate formation may occur.
Reasons for Freeze Protection:
1.
If the pilot sensing line becomes clogged or frozen, then
system pressure can be isolated from the pilot valve. This
will not allow the pilot to detect system pressure, open
and relieve the overpressure situation.
Recommendations for insulating and heat tracing pilot
operated safety relief valve:
Types of freeze protection:
a. Insulation by fiberglass blankets or wrap.
b. Heat tracing with electrical heat tape.
c. Radiant heat sources, such as a heat lamp.
For applications where heat tracing or radiant heaters are
used, the temperature should be limited to approximately
200ºF (93.3ºC) so that the elastomers are not damaged.
Higher temperatures may be allowed upon review of the
application.
Valve illustrations showing acceptable locations for insulation
are shown in Figures 8 and 9. Figure 8 shows a standard pilot
operated relief valve. Figure 9 shows a pilot operated relief
valve equipped with a heat exchanger.
24 | BHGE
Do not insulate
or cover
Heat Exchanger
top or bottom
Outside perimeter
of Heat Exchanger
may be insulated.
Pilot
Valve
Figure 9: POSRV with Heat Exchanger
© 2019 Baker Hughes, a GE company. All Rights Reserved.
Insulation
not required
for Bonnet
and Cap
Cover Plate
Main Valve
Base
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