CUI Major Incident # 0.2: Boxing Day gas blast due to Pipe Burst
Date and Place of the Incident:
On December 26, 2015, the sudden release of over 2 tons of high temperature, high-pressure natural gas took place due to the bursting of pipe at the North Sea platform of Marathon Oil's Brae, situated 250 kilometers north-east off the Aberdeen coast, United Kingdom.
Summary of the Incident:
- The release of natural gas took place due to the bursting of a corroded pipe.
- The accident occurred in Module-14, consisting of electrical equipment. The staff had been working in Module-14 in the morning but were away at the time of the incident.
- The force of the explosion was sufficient enough to bend the industrial cables and metallic handrails.
- The presence of staff members could have resulted in their fatality and injury. Moreover, the staff could also have experienced narcotic effects of methane breathing and the danger of asphyxiation from dwindling oxygen levels.
Root Cause of the Incident:
- Corrosion under insulation was the root cause of the incident.
- The insulation of the pipe was deteriorated over time due to weathering effects.
- The seepage of saltwater through the insulation resulted in corrosion under insulation (due to stress corrosion cracking and crevice corrosion)
Financial Loss to Freedom Industries:
Marathon Oil was charged with a criminal fine of £1,160,000 (for their violations) by Aberdeen Sheriff Court.
Environmental Impact of the Incident:
Health and Safety Executive (HSE) confirmed the release of 2,148 kilograms of gas into the environment due to the accident.
Fatality or injury due to the Incident:
No human injury or fatality was reported due to this incident.
Non-Compliance of Safety Guidelines and Reliability Practices:
- It was found by HSE that corrosion took place over the years. However, no inspection was carried out to check the corrosion under insulation.
- Marathon oil failed to comply with guidelines of CUI protection at vulnerable locations (Module-14 was identified as a vulnerable location in 2010).
- According to Marathon Oil’s ‘strategy’ document, ‘all pipework must be inspected every 36 months while its insulation must be replaced every 12 months’.
- It was revealed that the failed pipework had been in operation for 26 years and Marathon Oil failed to implement the guidelines.
- Marathon Oil did not perform a thorough visual inspection of the pipework regularly and continually approved the suitability of the pipework.
Recommendations to Avoid Corrosion:
The incident of corrosion under insulation could have been avoided if the following precautions had been followed by Marathon Oil:
- Proper maintenance of entire insulation and piping is necessary to avoid unforeseen events.
- Leak and crack detection mechanisms must be installed in insulated structures to ensure timely actions.
- Regular external and internal inspection of the pipes should be performed to detect and fix structural issues.
- Suitable corrosion protection mechanisms must be installed to avoid corrosion. Adequate techniques of corrosion protection include cathodic protection, internal and external coatings, internal tank liners (with regular replacements), maintaining suitable pH of the chemical mixture, and use of high alloy steels. Some of the protection mechanisms include:
- Application of thermal spray aluminum on steel to avoid corrosion under insulation (caused by general corrosion and stress corrosion cracking).
- Utilizing aluminum foil wrapping over stainless steel structures to inhibit stress corrosion cracking.
- Employing duplex alloys for enhanced corrosion resistance.
These techniques are congruent with best guidelines, industrial standards, and practices that
would aid in the prevention of corrosion under insulation.
Links to the photos/videos:
The incident report and the relevant image of the incidents can be accessed at the following web addresses:
https://app.croneri.co.uk/feature-articles/marathon-oil-fined-116m-boxing-day-gas-blast
https://www.bbc.com/news/uk-scotland-north-east-orkney-shetland-48341406
