“A Costly Mystery”

The March 2018 issue of Hydrocarbon Processing has an article entitled,

“A Costly Mystery” that discusses the ULSD fuel quality problem.

It is written by Rick Chapman and Jack Burgalzi of Innospec Fuel Specialties, USA.

The article was notable for the following reason:

Innospec worked with several refinery and distribution system partners recently, and found that microbial-induced corrosion was inducing the presence of low-weight acids and low acidic pH in TERMINAL storage tanks. They say it was a key discovery, and eliminated ethanol as the sole key component necessary that fostered MIC in ULSD storage.

The article also says that the exact cause of corrosive conditions is still unknown and requires further work seeking clarification of the microbe and acetic acid source is on-going. It also talks about high sodium (sodium hydroxide) that form metal soaps. Acidic corrosion inhibitors that combine with sodium ions to form fatty acid soaps. If the corrosion inhibitors added at the refinery to protect terminals and pipelines is involved in forming these soaps, then the corrosion protection expected from the inhibitor can get depleted. Innospec testing found that 23% of the ULSD samples taken at the dispenser did not meet NACE fuel corrosion test ratings for fuel leaving the refinery, and in the pipeline.