IOGP fatal incident report

Incident description:

Two contractors working on a weld repair on a section of 36" gas export pipeline were critically injured when the pipe dropped from the wooden blocks supporting it. Medical support services were immediately mobilised. CPR was performed at the scene and the injured workers were transferred to the site clinic, where the doctor confirmed that they had died.

What Went Wrong:

- The curved pipeline section elongated and deflected due to thermal expansion, which in combination with other forces, such as pre-stress, resulted in the incident end of the pipe moving inwards relative to the radius of curvature of the pipe, by a distance exceeding the width of the northeast end skid stack, and falling to the ground. - The lateral movement of the curved pipeline section was initially restrained by friction between the pipe and the skid stacks and potentially by wedging of the installed chocks. As stored energy continued to accumulate in the curved pipeline section, the restraining capability of the support skids / chocks was exceeded, and the stored energy was released in a rapid movement of the incident end of the pipeline towards the truck (pictured). Prior to that release, the pipeline appeared to be in the normal position on the skids. - The hazards revealed by this investigation (thermal expansion, differential heating and pre-stress, resulting in elongation and deflection of long curved pipe section, as well as the broader hazard of pipelines dropping from temporary support skids) were not appropriately recognized.

Corrective Actions:

- Recognize that suspended pipelines represent dropped object (working underneath) and stored energy (working alongside) risks, and fully consider these risks in associated job hazard analyses and risk mitigations. - While conducting risk assessments, in addition to focusing on obvious hazards of main work activities, ensure rigour in identifying less obvious and latent risks that could materialise under certain conditions. - If activities are to be undertaken in accordance with industry custom and practice, make sure these requirements are clearly communicated to those undertaking the task, fully understood by all stakeholders (including permitting authorities) and clearly documented.