PP (polypropylene) welding rod is the correct filler for welding polypropylene tanks, automotive battery boxes, ducting and chemical fabrications. Because a weld is only as strong as the match between rod and base material, polypropylene parts must be welded with a genuine PP rod — never PE or PVC.Techspan PP rod is extruded from virgin material for reliable, repeatable welds in workshop fabrication and industrial repair. Suited to chemical-process tanks, pipework, and fabricated PP components, it comes in 3 mm, 4 mm and 5 mm round profiles plus triangular and rectangular profiles, in 50 m and 400 m rolls. If you’re unsure whether your part is PP or PE, our plastics identification guide covers the burn and float tests that tell them apart.