Experimental Investigation of Pipeline In-Service Welding Process

Abstract

Welding of pipeline in active operation (called in-service welding) is an advancedtechnique employed to repair pipelines to safe transmission of petroleum or gas. A thermalexperimental study is accomplished on welding process of gas pipeline in this work. Anexperimental setup had been designed, manufactured and instrumented to estimate the methodfor repairing locally pipelines defects (such as cracks and holes wall surface) under the influenceof internal pressure. Also the thermal history of welding process was investigated experimentallyto three cases which are : traditional welding process with no fluid flows inside the test pipe, anin-service welding process considering air as the flowing fluid inside test pipe, and an in-servicewelding process considering the liquefied petroleum gas (LPG) as flowing fluid inside test pipe.Results show that direct deposition of welding metal on a through hole under the influence ofinternal pressure succeeded for flow rate less than (12lpm) and failed for flow equal or higherthan (12lpm) in which a sleeve repair is considered. The calculations are followed by a separatethermal stress analysis based on the thermal history.