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UK HSE Investigation into Offshore Gas Explosion

What happened?

The UK HSE has fined Marathon Oil UK LLC (Marathon) £1,160,000 following an investigation into a high-pressure gas release on the Brae Alpha offshore platform on 26 December 2015.  Eight-inch (20cm) diameter high pressure pipework in Module 14 on the platform suffered a catastrophic rupture as a result of ‘Corrosion Under Insulation’ (CUI), allowing over two tonnes of high-pressure methane gas to be released almost instantaneously.  The force of the high-pressure release caused significant and widespread damage in Module 14.  Fortunately, owing to the timing of the incident, there were no injuries.

What went wrong?

Investigation found that Marathon Oil had failed to undertake any suitable and sufficient inspection of the pipework that would have allowed the company to identify the risk and prevent the hazard from materialising.  These failures resulted in personnel on-board the Brae Alpha platform being exposed to an unacceptable risk of serious personal injury or death from fire and explosion, and also led to the UK HSE serving an Improvement Notice on Marathon Oil in January 2016, requiring the company to implement an effective hydrocarbon pipework inspection and maintenance regime.

The inspector noted:

“This incident is a further reminder of the ever-present hazards in oil and gas production, that if not rigorously managed can easily result in a potentially life-threatening event.  Corrosion Under Insulation (CUI) is a well-known risk and this incident should not have occurred.  During any normal period of operations personnel could easily have been working in, or transiting through Module 14, and they would almost certainly have been killed or suffered serious injury.  The timing of the incident and fact that the gas did not ignite was fortuitous.”

The press release can be found here.

Members may wish to refer to the following incidents where hidden corrosion was a causal factor:

Safety Event

Published: 30 September 2019
Download: IMCA SF 23/19

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