Analysis and optimization of welded joints of HDPE pipes during butt fusion welding: State-of-the-art and emerging directions

High-density polyethylene (HDPE) has become a preferred material for modern pipeline systems due to its exceptional advantages. Among various joining techniques, butt fusion welding is the most widely employed and cost-effective method for connecting HDPE pipes. In response to growing demands for improved weld quality and long-term reliability, this review presents a comprehensive synthesis of recent advances aimed at enhancing the overall performance of welded joints in HDPE pipelines. It begins with an examination of the intrinsic material properties of HDPE in relation to weldability, followed by an overview of the principles and procedures of butt fusion welding, and an in-depth analysis of the mechanisms and implications of welding defect formation. The review then turns to recent progress in both destructive testing (DT) and non-destructive evaluation (NDE) techniques for weld quality assessment, as well as the optimization of key welding process parameters. In addition, emerging modification strategies of HDPE material are highlighted for their potential to improve weld strength, structural stability, and overall joint integrity. Building upon these thematic areas, the review identifies existing technical barriers and unresolved knowledge gaps, and outlines future research directions aimed at advancing both fundamental understanding and practical solutions for the next generation of high-performance HDPE pipeline systems.