E. Freeze Protection
Type of Applications:
1. Applications where the process media, in the
liquid state, has a freezing point between the
ambient temperature limits of the local region.
2. Steam service applications where the pilot
operated valve is exposed to the climate,
extreme cold ambient 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 14 and 15.
Figure 14 shows a standard pilot operated relief
valve. Figure 15 shows a pilot operated relief valve
equipped with a heat exchanger.
XII. Recommended Installation Practices (Contd.)
Pilot Valve
Base
All Tubing
Insulation
not required
for Bonnet
and Cap
Main Valve
Base
Accessories
(I.E. Filters)
Figure 14: Pilot Operated Safety Relief Valve
Insulation
not required
for Bonnet
and Cap
Do not insulate
or cover
Heat Exchanger
top or bottom
Outside perimeter
of Heat Exchanger
may be insulated.
Cover Plate
Pilot
Valve
Main Valve
Base
Figure 15: POSRV with Heat Exchanger
28 | BHGE
© 2018 Baker Hughes, a GE company. All Rights Reserved.
