MIC ─ Leaving Its Mark on the World
As we discussed in a previous article, we discussed how microbiologically-influenced corrosion (MIC) – also known as microbial corrosion – occurs when sessile microorganisms alter the physiochemical conditions on a metal surface. MIC increases corrosion rates, leading to a premature and severe type of corrosion. Biocorrosion can be highly destructive, leading to disastrous consequences in several industries.
In this article, we outline three notable examples in the oil and gas industry, and how MIC can be influential in other sectors.
The Aliso Canyon Leak, 2015
The Southern California Gas Company (SoCalGas) provides gas to over 21 million customers in Los Angeles and Southern California. The utility company injects gas into natural underground storage areas. A fracture of the 7” casing and a 19” axial split was caused by external MIC.
The failure leaked around 109,000 metric tons of methane over a period of five months. The incident was the largest methane leak in US history and caused substantial gas supply shortage to power stations.
More than 8,000 households were evacuated. The cost to the utility exceeded USD 2 billion including civil lawsuits settled for US$ 1.8 billion on 27/9/2021.
Methane has 28 times greater global warming potential than carbon dioxide and indicates the environmental damage and effect on global warming.
The Prudhoe Bay Oil Spill, 2006
A 34” pipeline operated by BP and partners including Exxon Mobil Corp and ConocoPhillips spilled over 267,000 gallons of crude. It was the biggest oil spill in Alaska’s history and devastated 7,700 m2 of pristine land. The spill originated from a ¼” hole in the pipeline that was caused by internal MIC.
The company was fined US$ 255 million in addition to the loss of production and cost of containment. The pipeline was decommissioned and replaced with a 20” pipeline provided with facilities to enhance inspection and monitoring.
The incident caused shockwaves on the international market and the price of oil on NYMEX jumped by US$2.22 a barrel while BP shares dropped by 2%.
The El Paso Pipeline, New Mexico, 2000
An explosion in the El Paso pipeline in New Mexico caused a huge crater (around 51 feet wide and 113 feet long), damaged bridges, and cost the company a US$15.5 million penalty. Damage to property cost US$1 million. Multiple lives were lost.
The ensuing investigation showed the “presence of acid-producing bacteria in all samples obtained from the corrosion pit areas” with “striations and undercutting features that are often associated with microbial corrosion.” The presence of contaminants that included oxygen, hydrogen sulphide, and carbon dioxide also contributing.
It was a horrific event that could have been avoided with effective corrosion prevention. An error that El Paso was required to correct – costing almost US$90 million to upgrade the 10,000-mile pipeline system.
MIC Isn’t Restricted to Oil and Gas Structures
Though mostly studied by the oil and gas industry and because of the highly publicised and detrimental impact of failures in the energy sector, microbiologically-influenced corrosion affects other sectors, too, causing pitting corrosion, galvanic corrosion, and crevice corrosion, among others. Examples of microbiologically-induced corrosion include:
· Water Distribution Systems
Microorganisms that are present in water, like sulphate-reducing bacteria, can produce hydrogen sulphide gas that accelerates corrosion. The result can be pipe leaks and issues with water quality.
· Power Plants
Algae and bacteria can form biofilms on metal surfaces – particularly in heat exchangers and cooling systems. These biofilms can produce the conditions that accelerate corrosion, impairing heat transfer efficiency, reducing equipment lifespan, and increasing maintenance costs.
· Marine and Offshore Structures
Marine environments provide good conditions for certain microorganisms to thrive. MIC can affect the metal components of ships, offshore platforms, and coastal infrastructure – and attacking coatings and submerged structures – and increasing maintenance requirements.
· Water and Wastewater Treatment Facilities
The combination of aggressive water chemistry and microorganisms can lead to corrosion of pipes, pumps, valves, and other equipment in water and carbon-rich wastewater treatment facilities. The outcome is a reduction in efficiency of treatment processes and increased maintenance costs.
· Chemical and Petrochemical Plants
Colonising surfaces and forming biofilms that induce corrosion in pipelines, storage tanks, and other metal components. This can result in leaks, process disruptions, and safety hazards.
The Bottom Line
Disasters that are, at least in part, caused by microbiologically-influenced corrosion have left indelible marks on our economies, environments, and industries. They have caused horrendous environmental disasters, huge financial and reputational costs, and loss of lives.
The examples we’ve discussed in this article highlight the destructive nature of MIC, and the need to prevent it and use effective treatment regimes to mitigate it.
It’s crucial that we continue to expand our understanding of MIC, the susceptibility of materials to microbiologically-induced corrosion in conjunction with other corrosion mechanisms, and improve the evaluation of microbiologically-influenced corrosion. If we can achieve this, we can help to create a safer and more sustainable world for all in it. However, doing so means we must strive to overcome the challenges associated with MIC – a topic that we explore in our next article in this series.
“MIC is such a misunderstood field of the industry that not all failures are openly investigated. The examples in this article are the tip of the iceberg,” says Tony Rizk, PhD, Ex-Honorary Reader at Manchester University, and Course Lead.
“A particular problem is that some corrosion engineers have been reluctant to recognise MIC as a problem. In one case in which I was involved, a lead engineer (and a distinguished figure in the industry) did not believe in MIC and consequently the project design was commissioned based on only one SRB test. Strange, but true.”
To improve your knowledge and practical capability in the war against MIC, please email the Institute of Corrosion for information about our new MIC Training Course.
Articles in This MIC Corrosion Series:
Bio-Corrosion Basics: What Is MIC Corrosion?
Real Life Impacts of Microbiologically Influenced Corrosion
The Unique Challenges of Managing Microbiological Corrosion
Introducing ICorr’s Microbiologically-Influenced Corrosion Courses
(Image attribution: https://flickr.com/photos/33246316@N02/23807396891)