April 18, 2013 Washington DC-It seems that the pipeline corrosion that likely was the cause of Chevron’s Richmond refinery fire last year, seems to be present at other refineries too. An investigation by an independent agency working closely with the US Chemical Safety Board(CSB) and OSHA have found evidence of corrosion in the El Segundo refinery too. This implies that oil and gas installations everywhere, should take a closer look at corrosion in pipes, that may compromise the mechanical integrity of the installation, leading to possible ruptures and consequent fires and explosions.
In the El Segundo case, the pipeline walls have been found to have thinned by about 60%, which is alarming. This thinning could lead to rupture of the pipelines and possible release of toxic and flammable materials, that can cause a fire/explosion similar to that in the recent Richmond refinery case.
More from the CSB website below
The new report was completed this week by Anamet, Inc., an independent materials engineering and laboratory testing company. After the August 6, 2012, fire in Richmond, Chevron voluntarily inspected and upgraded corresponding sections of piping from El Segundo, which has a nearly identical crude unit. The tests compared sections of pipe from the #4-sidecuts in the two crude units. It was the #4-sidecut pipe in Richmond that released a massive quantity of combustible gas-oil and other hydrocarbons in August 2012. No release or incident occurred in El Segundo, and Chevron has since replaced the corroded piping with an upgraded metallurgy that is more resistant to sulfidation corrosion.
The removed pipe from El Segundo was secured and preserved for testing under an order from Cal/OSHA process safety inspectors, who recognized the similarity between the two crude units and sought to determine whether similar corrosion had occurred in El Segundo to what was observed in Richmond. The pipe was later transferred to the Anamet lab in Hayward, California, under a joint testing protocol. Chevron cooperated with the CSB in the testing.
The report’s main conclusion: “Sulfidation corrosion had affected the [Chevron] El Segundo samples to a similar extent as the [Chevron] Richmond samples had been affected.”
The report notes that both refineries processed similar crude oil, leading to sulfidation corrosion in the carbon steel piping used in both facilities, and that silicon content – which aids in corrosion resistance – was low in both cases. Older carbon steel piping, which is common in refineries, can have widely varying levels of protective silicon, a trace constituent that is hard to measure under field conditions.
“Consequently,” the report authors stated, “it is not surprising that the presence of thick sulfide scale on the inside surfaces of the pipe, and generally uniform wall thinning indicate that sulfidation corrosion was active during service of the El Segundo 4-sidecut, and that the general extent of sulfidation corrosion was similar in both systems. The obvious difference between the two 4-sidecut lines was that Richmond suffered more extensive corrosion in one component that resulted in rupture.”