Polyethylene welding wire is often used for repairing gouges in HDPE pipe or sheet, or welding outlets on HDPE pipes and poly tanks. Polyethylene welding rod comes in different thicknesses and lengths, and is also known as plastic welding wire or plastic welding rods. Round poly welding wire comes in 3 mm & 4 mm width, in 3 kg or 10 kg rolls. 4 mm circular poly welding rod is available in hot gas welding yellow, for use with yellow plastic or gas lines. 5.7 mm triangle poly welding wire is available in 220 m coils, because the triangular shape suits some PE extrusion welding guns. Triangle PE welding rod is commonly used for tack welding with a hot air gun, before fully welding with an extrusion gun.