A high natural gas pressure alarm occurs when the downstream pressure exceeds the permissible limit. This is a significant safety event and should not be addressed by simply increasing the pressostat setpoint.
Potential causes
Common causes include regulator failure, incorrect setpoint, problems with the pilot or impulse line, inability of the monitor regulator to take over, or improper operation of the slam-shut.
Checking actual pressure
The reading must be verified with an appropriate instrument. If the manometer and the pressure transmitter show different values, the reliability of the instruments must be checked.
Regulator check
If the pressure rises when consumption decreases, there may be a lock-up problem or a leak from the regulator seat.
High pressure pressostat
The setting, the actual pressure at the connection point, and the electrical operation of the contact are checked. The setpoint is not changed without documentation.
Protection systems
In industrial installations, there may be a monitor regulator, relief valve, and slam-shut. Their sequence must be correctly adjusted.
After a trip
The installation is not restarted until the cause is identified and it is confirmed that the protections are functioning normally.