Assessment of API pipeline steel surface and its environmental vulnerability

Petroleum pipelines provide a safe and economical way of transporting commodities such as natural gas and crude oil in large volumes. They form part of a large and complex infrastructure that connects raw resources, processed products and consumers together. This has made pipeline an integral part of the oil and gas industries. API grade pipelines may be either seamless or welded pipes. The welded manufacturing process may include a filler metal during welding as in submerged arc and gas metal-arc welding, or may not include a filler metal as in continuous welding or electric resistance welding and laser welding. One of the major concerns is corrosion on welded joint. Stress corrosion cracking is major concern in pipeline steel due to the susceptibility in the weld region, changes in chemical compositions, microstructure and the presence of residual stresses. This study focuses on the concise assessment of possibility of failure in pipelines and the trend of pipelines materials in service.