Corrosion in the energy industry
“Corrosion – the deterioration of a metal or its properties – attacks every component at every stage in the life of every oil and gas field.”
Corrosion is the unintentional deterioration of a metal caused by reaction with its environment. Almost all environments cause metal to corrode, particularly in the energy industry where conditions are difficult. The consequences are severe – corrosion causes pipeline failure, leaks, reduced production through closedowns or limited flow, ecological damage and potentially enormous loss of money.
Identification and detection
OMS offer sophisticated inspection solutions that help clients identify corrosion problems quickly and accurately. Our inspection systems can detect corrosion in some of the most difficult to reach locations where standard techniques do not work. We can provide detailed information to our clients on a pipe’s internal condition and the specific location of any corrosion that enables them to manage any repair or replacement efficiently. For more information about our corrosion identification and detection services click here.
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Energy industry challenge
Corrosion is one of the most important challenges facing the energy industry. Oil and gas pipelines carry inherently corrosive hazardous materials on the inside and are subjected to harsh conditions such as seawater and extreme temperatures on the outside. In nuclear power plants pipelines and reactors must also be able to withstand irradiated coolant water that can reach temperatures of 300°C and 120 bar.
Pipeline failure
Estimates suggest corrosion is responsible for more than 25% of pipeline failures, including many oil disasters such as the Prudhoe Bay oil spill, when 212,000 gallons of crude oil leaked from a damaged pipeline owned by BPXA in Alaska in 2006. Severe corrosion under sediment in a section of pipe caused the leak, which was more than three times larger than any before on the North Slope in Alaska. BPXA had to shut down production at the facility, which at that time was responsible for 2.6% of US gasoline, resulting in costs of $100m to replace damaged pipeline, a 2% slump in the share price and considerable harm to the company’s reputation.
Most common types of corrosion
In the energy industry the most common form of corrosion happens when steel comes into contact with water and rusts. In oil and gas production internal corrosion within pipelines and wells is influenced by the temperature, concentration of carbon dioxide and hydrogen sulphide, flow velocity, water composition and the steel’s surface condition.
Galvanic corrosion occurs when two metals are in contact with each other and an electrolyte, such as water. In these conditions the less noble, or inert, metal corrodes preferentially. This type of corrosion is particularly prevalent at offshore marine sites.
Stress corrosion cracking is usually associated with environmental factors such as high temperature and pressure. It causes localised corrosion which can progress quickly and result in sudden, unexpected metal failure.
Corrosion under insulation is localised external corrosion that develops in carbon and low alloy steel equipment that has been insulated. It occurs when water is in contact with insulation exposing equipment to water and oxygen. Read our chairman’s thoughts on corrosion under insulation here.
Oxygen corrosion – getting into pipes through vents or leaking seals, or carried in high velocity fluid flow, oxygen accelerates the destruction of metal and magnifies the corrosive effects of carbon dioxide and hydrogen sulphide, causing pitting and uniform corrosion.
Erosion corrosion is the continual removal of the passive layer of corrosion products (e.g. rust) from a pipe’s wall. This is always experienced in a high turbulence flow regime and is accelerated by the presence of abrasive material.
Sweet corrosion occurs when carbon dioxide mixes with water to form carbonic acid, causing pitting on the metal’s surface.
Sour corrosion is deterioration caused by steel coming into contact with hydrogen sulphide and water. It is extremely damaging to pipe, resulting in pitting and cracking.
Bacterial activity within pipes increases fluid toxicity and can form slime, which leads to microbiologically induced corrosion.
Preventing corrosion
Corrosion causes losses of many billions of dollars per year to the energy industry so attempts to prevent it are constant. In the harsh conditions of energy production many operators have found that preventing corrosion is almost impossible so instead attempt to manage the rate of deterioration, taking corrosion into account when designing new pipelines, investing in corrosion-resistant alloy pipes and employing corrosion engineers to help them mitigate risks.
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Posted 29.09.2020
[5 minute read]