The development of an automated system for ultrasonic mapping of autohesion and other joining related defects in heat-fused polyethylene gas distribution pipe joints is discussed. Leading into the system description a brief summary of how polyethylene is joined and the types of defects that can occur is presented. Elastic wave interactions with polyethylene and autohesion defects are outlined to define the flaw detectability problem, particularly, as it relates to the requirements for development of an automated system.