SEDL / STP / STP918-EB / STP19330S

Applied Fracture Mechanics for Assessing Defect Significance in a Crude Oil Pipeline

Christensen, C
Metallurgist, Korrosionscentralen, Copenhagen,

Hill, RT
Consultant, J. P. Kenny & Partners Ltd., London,

Pages: 14    Published: Jan 1986

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Abstract

The integrity and service life of a pipeline will depend, to a large extent, on the fracture toughness properties and subcritical crack growth resistance of pipes with defects either inherently present or introduced during construction or service. Unstable fracture from crack like defects can occur if the fracture toughness of the line pipe material is inferior, whereas subcritical crack growth can occur under sustained load and cyclically varying loads (fatigue). Both of these subcritical growth mechanisms can be strongly influenced by the internal pipe environment (hydrogen sulfide, carbon dioxide) and external environment (corrosion, cathodic protection).

A case history of the application of fracture mechanics for evaluating the static fracture toughness and subcritical crack growth resistance of an external longitudinal weld toe crack is discussed.