A contractor was injured and evacuated after a gas release incident on an offshore facility in the Gulf of America. The incident occurred while a contract employee was performing maintenance on an E-body control valve on a six-inch gas line. BSEE’s investigation found that residual pressure estimated at 128 psi inside the six-inch gas line was released during disassembly and replacement of the valve’s trim and seat. The sudden release caused the valve’s bonnet flange, weighing approximately 50 pounds, to be forcefully ejected. The flange struck the worker in the chest and abdomen, knocking the worker backward onto the elevated scaffold platform. The worker was evacuated for treatment and evaluation. Injuries included bruising and abrasions to the left abdomen wall and chest, a laceration behind the left ear, and abrasions to the left knee.
Incident Findings:
- Incomplete job safety analysis (JSA): The JSA was not reviewed or signed by the platform’s person in charge (PIC), as per policy.
- Inexperience and procedural gaps: The worker had less than two years of field experience under mentorship and was unfamiliar with key procedural requirements, including verifying the gas line’s condition through proper isolation checks and ensuring all necessary approvals and safety documentation were complete before starting work.
- Miscommunication: The worker began work without PIC approval and without notifying the PIC. Additionally, the worker had not assigned an operator familiar with the production process to assist. There was no clear discussion of the scope of work or hazards. The worker assumed the gas line and control valve were fully depressurized, based on comments made earlier that morning.
- Unauthorized use of scaffolding: The worker used a scaffold tagged “do not use” due to a missing ladder and kick plates. The worker was also working more than six feet above the main deck without fall protection such as a full-body harness and retractable lifeline.
- Failure to verify zero energy state: An energy isolation permit, required to confirm the gas line was fully depressurized, was not completed. The worker began the task without verifying the line was free of trapped pressure.
- Failure to follow procedures: Original equipment manufacturer (OEM) guidance requires at least four nuts should be left on the studs and partially backed off during bonnet flange maintenance and disassembly. This precaution prevents the flange from being forced upward if trapped pressure is present. In this case, the worker did not keep the safety nuts on the studs.
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