COMPLETING THE JIGSAW GETTING TO KNOW YOUR STRESS CORROSION CRACKING

摘要

WHAT IS STRESS CORROSION CRACKING? Stress corrosion cracking(SCC)is a form of environmental cracking found worldwide, on both liquid and gas pipelines.External SCC requires the presence of three fundamental elements in order to occur: a tensile stress, a corrosive environment and a susceptible material(Figure l).SCC literature suggests that pipelines with higher hoop stress, i.e., stress due to internal pressure, are more susceptible to SCC.A corrosive environment often forms as a result of damaged coating that exposes the pipeline surface.This, in combination with a poor cathodic protection(CP)system, can lead to external corrosion and an increased risk of SCC.All steel pipelines are technically susceptible to SCC, but modern pipelines with higher grade steel are considered less susceptible to SCC than older and lower grade pipelines.