New Standard Addresses H2S Corrosion
The British Standards Institution (BSI) has issued a new standard for testing a common and dangerous type of corrosion and cracking in oil and gas pipelines.
The new document, BS 8701: Full Ring Ovalization Test for Determining the Susceptibility to Cracking of Linepipe Steels in Sour Service—Test Method, covers cracking problems in steel pipelines, caused by the presence of wet hydrogen sulfide (H2S).
Environments that contain H2S are considered to be “sour,” as opposed to “sweet.” When sour corrosion takes place, iron sulfides are formed on the corroded surface. This then leads to hydrogen accumulation, which is eyed as a cause of pipeline cracking.
Sulfidic corrosion was blamed for the August 2012 leak and subsequent fire at Chevron’s Richmond, CA, refinery.
The new standard updates the U.K.’s Health and Safety Executive’s guidance document OTI 95 635, addressing the same topic, published in 1996. According to BSI, the previous standard was not up to date with regard to sour service lines.
Ring Specimen Test
According to BSI, the standard discusses assessing a pipeline’s susceptibility to cracking by testing a ring specimen “where a stress level is applied to two regions of the specimen” and a sour test solution is applied. The specimen is monitored and studied to determine whether cracking begins or expands.
While sour corrosion is also known to take place in wastewater pipelines, the new standard from BSI is tailored to the oil and gas industry, and was authored with the help of industry experts, the organization says.
“Having a test method such as BS 8701 in place allows the correct tests for identifying the damaging levels of corrosive hydrogen sulfide gas, to be carried out,” said David Fatscher, Head of Market Development for Sustainability and Energy at BSI. “It can act as an early warning system that offers reassurance that everything is being done to safeguard the environment.”