ISO 8639:2016 specifies test methods for flexible non-thrust resistant socket-and-spigot joints with elastomeric sealing elements for buried and above ground glass-reinforced thermosetting plastics (GRP) pipeline applications. It covers methods of test for the leaktightness and resistance to damage of the joint only, when subject to specified combinations of longitudinal extension (draw), angular movement (angular deflection), compression (deformation) perpendicular to the pipe axis and internal pressure. ISO 8639:2015 is applicable to joints for either pressure or non-pressure applications.