Date of incident: March 2015
Notice of incident number: 2015174170064
Employer: Oil and gas well service company

Incident summary

Workers were conducting hydraulic fracturing stimulation processes on a gas well. During a fracturing operation at the well site, there was a need to bring nitrogen (N₂) back on line. This required the N₂ line to be vented so the pressure could then be brought back up. A worker was manually turning the vent valve on the high‑pressure N₂ gas line to bleed off pressure when the pipe spun and fatally struck the worker.

Investigation conclusions

Causes

• Uncontrolled hazardous movement of nitrogen line: A worker was manually bleeding the high‑pressure N₂ line at the vent valve when the pipe moved, striking the worker and causing fatal injuries. It is possible that the worker bled the high‑pressure N₂ line too quickly.
• Remote‑controlled vent valve not used: A vent valve was incorporated into the high‑pressure N₂ line to allow for the bleeding off of N₂; however, the vent valve needed to be manually turned. The use of a remote‑controlled vent valve would have kept the worker out of the high‑pressure exclusion zone and away from the hazards associated with bleeding a high‑pressure N₂ line.
• Insufficient controls of hazardous energy: There was no isolation or control of the hazardous energy in the high‑pressure N₂ line due to the absence of restraints in the portion of the line with the vent valve. The N₂ line, including the swivel joints, were not restrained from hazardous movement and not secured to the nitrogen pumper. This enabled the vent valve to strike and fatally injure the worker.

Underlying factors

• Inadequate safe work procedures: The safe work procedures in place for rig‑in did not include the use of restraints on the high‑pressure N₂ line and did not require securing the N₂ line to the pumper unit. There were no safe work procedures in place for bleeding the N₂ line safely, which should have included direction on the use of a remote‑controlled vent valve.
• Inadequate supervision: The well service company’s supervisors did not ensure compliance with the Occupational Health and Safety Regulation in relation to securing high‑pressure lines, safe work procedures for bleeding the N₂ line, and the use of a remote‑controlled vent valve. The use of line restraints was not corporate policy but was determined by what the customer required (in this case, the prime contractor), in contravention of the Regulation.
• Ineffective systems and processes to ensure compliance: The prime contractor did not ensure compliance with the Regulation in relation to securing high‑pressure lines, safe work procedures for bleeding the N₂ line, and the use of a remote‑controlled vent valve. The previous year, WorkSafeBC had provided education to the prime contractor in relation to securing high‑pressure lines; however, the prime contractor failed to ensure compliance with the Regulation and relied on the contractor’s expertise.

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