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

Eng. Failure Analysis, Elsevier.

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