Date of incident: September 2022
Notice of incident number: 2022177910004
Employers: Natural gas producer (prime contractor); oil and gas service provider

Incident summary
A worker at an oil and gas wellsite was performing a leak test on a flow piping system that went from a nitrogen pumper truck to a wellhead. The worker released the pressure from the flow piping system, and the sudden release of pressure caused movement in the system. The worker was struck by part of the equipment and sustained serious injuries.

Investigation conclusions

Cause

• Worker released pressure on flow piping system while standing nearby. The employer did not ensure a remote valve was used during the well-stimulus operations, which involved pumping inert nitrogen gas through the flow piping system and had pressures exceeding 2 000 kPa (290 psi). The use of such a valve ensures workers are not in a hazardous zone created by the release of high-pressure nitrogen, which could cause asphyxiation or movement of the flow piping system. Instead, the worker released the pressure on the flow piping system while leaning on or standing next to the flow piping hose. The flow piping hose recoiled from the sudden release of pressure and struck the worker, who was seriously injured.

Contributing factors

• Inadequate safe work procedures. Neither the employer nor the prime contractor developed and implemented adequate safe work procedures for the work task on the day of the incident. This left workers on site with inadequate or non-existent information about how to complete the well-stimulus operations being conducted. Had either employer developed adequate safe work procedures, workers would have had specific step-by-step instructions to complete the task and adequate control measures in place.
• Inadequate oversight.
  • On the day of the incident, a representative of the prime contractor was active on site, chairing the morning safety meeting, completing walkarounds of the work area, and directing the work tasks. However, the prime contractor did not identify the hazards and implement controls related to the work tasks. It also did not ensure that regulatory requirements, such as the use of remote valves and an adequate restraint system, were met. The prime contractor did not establish and maintain an adequate system or process that would ensure compliance with the OHS provisions of the Workers Compensation Act and with the Occupational Health and Safety Regulation for its contractor at the worksite.
  • The prime contractor did not ensure that the employer was using a remote valve for the well-stimulus operations; did not ensure that an adequate restraint system was used and that the whole flow piping system was restrained from undue horizontal, vertical, or swinging motion; and did not ensure that adequate leak tests were completed and documented as required. In addition, it did not ensure that the scene was secured (kept undisturbed) after the incident, did not report the serious incident to WorkSafeBC, and did not ensure that adequate first aid procedures were developed for the site.

Other health and safety issues

• Inadequate piping securement. The employer had whip checks (restraints) installed on the flow piping hose prior to the incident. However, the whip checks were inadequate to restrain the flow piping system from undue horizontal, vertical, or swinging motion such as that caused by a sudden release of pressure. The use of an engineered or manufactured restraint system with taut restraints and appropriate anchor points should reduce the movement of the piping if there is a pipe failure or inadvertent movement.
• Inadequate leak testing. Two leak tests were performed on the flow piping system, but neither time did the employer record the results as required. The records of those tests should have identified the components of the flow piping system being tested and included the pressure to ensure that any leak-off pressure was within acceptable limits. The first leak test did not meet the recommended time required of 10 minutes, and there was no information recorded for the second test, during which the incident occurred.
• Failure to report. The incident, which occurred at approximately 10:00, was not reported to WorkSafeBC until 20:30 that night. The prime contractor and the employer ought to have known by 14:00 to 14:30 that the worker’s serious injuries were immediately reportable to WorkSafeBC and should have reported this incident much sooner.
• Failure to secure the scene. The prime contractor and the employer failed to secure the scene after the incident. The employer demobilized its equipment and removed it from the worksite on the day the incident occurred. Once the worksite had been made safe after the incident, the employer had a responsibility to preserve the scene both to comply with regulatory requirements and so that it could conduct its own investigation and take any necessary corrective actions.
• Inadequate first aid assessment and procedure. The prime contractor did not ensure that a first aid assessment and first aid procedure were completed for the worksite as per its own policy and the Regulation. Instead, it relied on information from a nearby worksite with different work activities and hazards, and the directions provided to and from the nearest medical facility were incomplete.

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