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High-density polyethylene (HDPE) piping systems are increasingly recognized for their exceptional corrosion resistance, flexibility, long-term mechanical durability, leak-free monolithic joints, fast and easy installation, and overall cost-effectiveness across a range of industrial sectors, from municipal water and gas networks to safety class nuclear power plant piping applications. The long-term reliability of these systems hinges critically on the integrity of butt-fusion (BF) joints, which often represent the most vulnerable points under operational stresses and environmental conditions. This review serves a dual purpose, it distils best practices for welding-condition optimisation and evaluates joint-integrity assessment methods, offering a unified guideline for butt-fusion welding (BFW) of HDPE pipes. Fundamental welding parameters such as fusion temperature, interfacial pressure, and heating/cooling durations that govern polymer chain interdiffusion and resultant joint strength are explained. Key standards are examined for their differing recommendations, underscoring the need for harmonized global guidelines. Standard weld integrity testing methods and recent advancements in mechanical testing, ranging from short-term tensile and impact assessments to long-term creep and slow crack growth (SCG), were critically reviewed. Emerging approaches such as, tapered-waist tensile (TWT) specimens, and hydro-axial tension (HAT) evaluating the full joint thickness, offer steps toward addressing the pronounced limitations of existing test methods revealed. The review concludes by highlighting critical research gaps, including real-time weld monitoring for proactive defect mitigation, adaptive multi-stage pressure protocols, and the development of reliable qualification and testing methods specifically tailored to large-diameter, thick-wall HDPE pipes. Addressing these issues is pivotal for advancing BFW performance, ultimately fostering globally standardized, next-generation HDPE pipelines with trustworthy reliability in high-stakes engineering applications. • Synthesizes fundamental butt fusion welding (BFW) parameters—fusion temperature, interface pressure, and heating/cooling durations—and their impact on HDPE joint integrity. • Evaluates and compares international standards (ISO 21307, ASTM F2620, DVS 2207) for BFW, underscoring the need for harmonized guidelines. • Analyzes mechanical testing methods (short-term tensile/impact and long-term creep/slow crack growth) and highlights microstructural factors affecting weld performance. • Discusses emerging non-destructive testing techniques, including phased array ultrasonic testing (PAUT) and microwave imaging, for defect detection. • Identifies critical research gaps in real-time weld monitoring, adaptive multi-stage pressure protocols, and multifactor aging conditions to drive future BFW innovations.
Alhatti et al. (Fri,) studied this question.