The butt fusion tensile test ISO 13953 is a mechanical test used to evaluate the strength and integrity of the butt-fusion joints in High-Density Polyethylene (HDPE) piping systems. This test assesses the joint's ability to withstand axial (tensile) forces, which are important for determining the reliability and performance of the welded joints. The results of the HDPE butt fusion tensile test are analysed to determine the tensile strength of the joint. Tensile strength is the maximum stress the joint can withstand while being pulled apart. Ductility is another mechanical property assessed these measures its ability to undergo plastic deformation without breaking. In the context of HDPE butt welds, ductility refers to the joint's ability to deform and stretch before failure when subjected to tensile or other mechanical forces. The ductility of an HDPE butt weld is an essential property to ensure that the joint can withstand mechanical stresses and maintain its integrity in various applications.