Sudden release of stored energy fatally injures two workers

What happened?

Two workers were performing a weld repair on a section of 36" (91cm) gas export pipeline supported by wooden blocks.

The pipe fell from the blocks, injuring the two workers.

Cardiopulmonary resuscitation (CPR) was performed at the scene.

The injured workers were transferred to the site clinic, where they were confirmed deceased.

Why did it happen?

The curved pipeline section elongated and deflected due to thermal expansion, differential heating, and pre-stress. These changes resulted in the end of the pipe moving inwards and falling to the ground.

As stored energy accumulated in the pipeline section, the skids and chocks could not restrain the lateral pipe movement any longer.

The stored energy was released in a rapid movement of the pipeline, which fatally stroke the two workers.

Thermal expansion, differential heating, pre-stress, stored energy, and the suspended pipeline as a potential dropped object have not been identified as hazards.

What did they learn?

Suspended pipelines represent both a dropped object and stored energy hazard. Consider these risks in job hazard analyses and risk mitigations.

Ensure all risks are identified during risk assessments and safeguards are put in place. Consider both obvious hazards associated with the main working activities, as well as less obvious hazards that could occur under certain conditions (e.g. thermal stress).

Ensure activities are carried out according to good industry practice. Procedures should be communicated, documented in work permits and understood by all personnel involved.

Ask yourself or your crew

How do you verify there is no stored energy within the system you are working on?

How can you check if suspended pipe sections are adequately supported by the blocks / chocks installed to prevent unintentional movement?

What hazards should you look out for during today’s job?

What safeguards do we have in place to prevent something like this from happening here? How can we improve?

What happened?

Two workers were performing a weld repair on a section of 36" (91cm) gas export pipeline supported by wooden blocks.
The pipe fell from the blocks, injuring the two workers.
Cardiopulmonary resuscitation (CPR) was performed at the scene.
The injured workers were transferred to the site clinic, where they were confirmed deceased.
Why did it happen?

The curved pipeline section elongated and deflected due to thermal expansion, differential heating, and pre-stress. These changes resulted in the end of the pipe moving inwards and falling to the ground.
As stored energy accumulated in the pipeline section, the skids and chocks could not restrain the lateral pipe movement any longer.
The stored energy was released in a rapid movement of the pipeline, which fatally stroke the two workers.
Thermal expansion, differential heating, pre-stress, stored energy, and the suspended pipeline as a potential dropped object have not been identified as hazards.
What did they learn?

Suspended pipelines represent both a dropped object and stored energy hazard. Consider these risks in job hazard analyses and risk mitigations.
Ensure all risks are identified during risk assessments and safeguards are put in place. Consider both obvious hazards associated with the main working activities, as well as less obvious hazards that could occur under certain conditions (e.g. thermal stress).
Ensure activities are carried out according to good industry practice. Procedures should be communicated, documented in work permits and understood by all personnel involved.
Ask yourself or your crew

How do you verify there is no stored energy within the system you are working on?
How can you check if suspended pipe sections are adequately supported by the blocks / chocks installed to prevent unintentional movement?
What hazards should you look out for during today’s job?
What safeguards do we have in place to prevent something like this from happening here? How can we improve?