Pipelines carrying heavy crude oil may be subject to corrosion caused by deposition of sediments, a
sludge containing oil, water, and bacteria in a particulate matrix. A standard testing protocol was
developed with the participation of five inhibitor vendors. The test protocol includes inhibitor
evaluations based on (1) Filming Effectiveness, (2) Partitioning Studies, (3) Sludge Corrosivity and
Inhibitor Tests, and (4) Bacterial Kill Studies. The results of the different tests and the relevance of
each test with regard to the application are discussed. A successful bacterial kill test approach was
established. Initial exposure tests of coupons covered with inhibited sludge in oil are most
representative of the pipeline environment, but results were variable. Improvements to the test
procedure are presented and explored.
Key words: inhibition, underdeposit corrosion, sludge, bacteria