Electro-fusion　welding　is　a　common　method　for　high-density　polyethylene　(HDPE)　pipes.　It　has　a　high　degree　of　automation　and　mature　technology.　However,　during　the　welding　process,　various　buried　defects　are　easily　generated.　In　this　paper,　HDPE　pipes　with　welding　defects　were　processed,　and　X-ray　technology　was　used　to　detect　the　defects.　The　results　show　that:　The　X-ray　detection　technology　is　sensitive　to　the　defects　of　sockets　and　ultralight　clay-filled　holes.　But　it　is　difficult　to　distinguish　the　size　of　the　holes.　Unfilled　holes　are　partially　fused　during　the　welding　process,　which　makes　them　difficult　to　detect.　In　addition,　the　defects　of　cold-welding　and　unscratched　oxide　skin　cannot　be　detected.　©　Published　under　licence　by　IOP　Publishing　Ltd.