Insufficient water in boiler results in overheating and damage
A high-pressure steam boiler was damaged due to overheating, after it was found running dangerously low on water.
A chief engineer of a processing facility reported a low water incident involving a high pressure steam boiler. The boiler was not emitting steam and was leaking water from its back cover.
It was found that the boiler was running low on water and did not have any water level visible in the sight glass. The low water cut-off safety device failed to prevent the boiler from operating with the low water condition.
An investigation of the incident noted the following:
- The combustion control was found to be operational.
- The boiler controls were wired according to the manufacturer’s instructions.
- The chief engineer reported that a shift engineer had performed the low water cut-off safety device test incorrectly.
- The chief engineer also reported that the mechanism for the manual reset button was faulty and did not reliably return to the reset position.
- There were no records to indicate that the low water safety controls had been replaced according to the manufacturer’s instructions.
As a result of the safety device failing to stop the boiler from operating during the low water condition, the boiler’s rear tube sheet, tubes and combustion chamber were damaged due to overheating.
It is probable that the incident was caused by inadequate preventative maintenance and testing of the safety devices, combined with the age of the equipment.
The permit holder was ordered to correct all non-compliances, including replacement of faulty controls, repair of damaged equipment and adherence to maintenance record requirements.