DVS 2212-1:2006 Qualification Testing Of Plastics Welders - Qualification Test Groups 1 And 2 - Hot Gas Welding With The Torch Separate From The Filler Rod (Wf), High Speed Hot Gas Welding (Wz), Heated Tool Butt Welding (Hs), Sleeve Welding With An Incorporated Electric Heating Element (Hm), Heated Tool Sleeve Welding (Hd) And Hot Gas Extrusion Welding (We)