LOTOTO valve isolation
Where applicable, the area unit shall formulate and implement a manner regarding the isolation of remote equipment (valves or electrical switches, etc.) to ensure that energy has been isolated during the locking process. Note: There may be situations where devices cross regions.
For electric valves, the power supply of the valve should be cut off and Lockout Tagout during isolation. For pneumatic valves, if permitted, the air supply line should be cut off from the execution unit and Lockout Tagout; otherwise, the air supply pipe should be disconnected and listed.
Inadequate isolation of cases
A corroded bursting disc is due for inspection. An operating permit has been issued, but no device specific isolation sheet has been executed. The system takes only valve isolation, two of which are automatic valves. The system was not fully decompressed and remained at about 0.25 Barg (3.6 PSIg).
As the maintenance technicians began unscrewing the flange bolts that held the bursting disc in place of the bursting disc holder, there was a loud bang and they saw the bursting disc shoot from the drain and hit the ground. The bursting disc has been partially detached from its holder and partially torn. Luckily no one was hurt.
There are apparent flaws in the work permit system and the energy isolation program. Work permits should be issued after quarantine confirmation. In this case, single valve isolation alone is not enough; And there is no effective verification after the quarantine is completed.