Qualification of Welding Procedures for ExxonMobil High Strain Pipelines

Abstract

Weld procedure qualification methodologies for ExxonMobil high strain pipelines are presented. ExxonMobil has been involved in the design and construction of high strain pipelines for both onshore and offshore applications. These projects have included onshore applications involving potential seismic activity (fault displacement and soil liquefaction) as well as arctic applications that may involve displacements associated with frost heave and thaw settlement. Recent offshore installations have been designed and constructed to accommodate potential displacement caused by ice scour. Some of these installations have been designed to accommodate in excess of 3% longitudinal tensile strain demand. A critical element of the overall pipeline design is the qualification and validation of acceptable strain capacity for the pipeline girth welds. A girth weld qualification test program, based on large scale proof testing (i.e., curved wide plates) has been developed and executed.

Latest developments in mechanical properties and metallurgical features of high strength line pipe steels

“…Subsequently, the rolling and cooling procedures are very effective in achieving a grain structured (low angle boundaries) microstructure which hinders the dislocation mobility, resulting in a perfect combination of strength and toughness. This microstructure is also developed to ensure fully ductile failure behaviour and high crack arresting behaviour at temperatures as low as -40 °C (arctic conditions) [14,30].…”