A major leak in a crude oil tank: predictable and unexpected root causes

PABLO CIRIMELLO; GUILLERMO CARFI; ,JOSE LUIS OTEGUI

Leipzig

Conferencia; ICEFA 7, 7th Int. Conf. on Eng. Failure Analysis.; 2016

ELSEVIER

A 2000 m3 washing tank at a crude oil treatment plant suffered a structural collapse involving the total loss of integrity. A fast fracture spread from a sector of the shell with very severe thickness reduction extended over an area of more than 5 m2, due to combined internal and external corrosion. The fracture bent and propagated horizontally, at the shell-roof intersection and at the joint between second and third courses, causing the almost instant opening of a large window. Due to the large initial leakage flow, the containment enclosure wall could not hold the spilled water and hydrocarbon mixture. The leaking wave overpassed the wall, and burst a gate from its rails in the wall. The company managed to avoid the spilled oil from reaching a nearby river and the sea coast, which could have generated a very important environmental impact. This near-miss led to a root cause analysis. Fracture and fluid dynamic models were developed to understand the origins of the spill. The influence of tank quality, maintenance adequacy, and corrosion prevention are discussed.