Abstract
A grade TP-316LN austenitic stainless-steel pipeline was found to undergo microbiologically influenced corrosion after 3 months of being hydrotested using demineralized water. The demineralized water was left half-filled in the pipeline for the mentioned 3 months after the hydrotest. Fine and deep pits were found to develop at the weld zone and at the far HAZ. SEM investigation showed that the corrosion was caused by bacterial colonies of rod-like bacteria. The cause of the corrosion was investigated by means of EDS analysis which showed that the corrosion was caused by selective leaching of Cr, Ni and Mo into the water phase. The type of corrosive attack was found intergranular rather than transgranular.