Cause & Consequence
- Uncontrolled release of a flammable gas or liquid
Specific Incident Equipment
A flange management tagging system was in place for all planned breaks into the process. During the shutdown, the scope of the work changed and this required the valve to be open instead of closed. However, it was still identified on the operations shutdown drawing as closed (and not disturbed) and therefore no line break tags were fitted. The line walk and N2 testing prior to start up did not identify the open valve.
- Put the step of ensuring all breaks have been tagged into the N2 testing contractor’s working procedures
- Reiterate of the importance of tagging each and every break – using this incident as an example.
- Introduce a technician’s N2 test sign off sheet to verify that all valves have been returned to their normal operating position following N2 testing. (Separate to the line walking procedure.)