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Hot Torque of Glass Gage
When a new glass gage is installed in high temperature service and it is not equipped with
spring washers, a hot torque procedure must be performed. This ensures that all bolting and
components are properly seated for optimum performance. This procedure must also be
performed after any maintenance is done to the equipment.
All work must be done by a qualified technician. All plant rules and procedures must be
followed, including any lock out / tag out requirement.
The hot torque procedure should be performed as follows:
1. The gage should be in service long enough for the equipment to reach operating
temperature, or at least 200º F (93º C).
2. Upon reaching the desired temperature, isolate the glass gage from service.
3. Fully open the drain valve to evacuate pressure and process fluid from the gage.
4. Immediately re-torque the gage nut to the values stated on page 16. There should be
rotation of approximately 1/8th of a turn or more. The proper torque pattern is also
diagrammed on page 16.
5. If there is no movement in the nut/bolt, the equipment was not heated properly. Repeat
the procedure.
6. Once the hot torque procedure is completed, close the drain valve and return the
equipment to service. Carefully check for any equipment leaks and verify proper
operation of the glass gage. Follow the procedure in Bringing Gage Into Service.
