DIN 16961 Thermoplastics pipes and fittings with profiled outer and smooth inner surfaces:

Part 1: Dimensions
Part 2: Technical delivery conditions
DIN 16961.1:2010-03 applies to thermoplastics pipes with profiled walls and smooth inner surfaces made from polyethylene (PE 63, PE 80, PE 100 and PE-HD), unplasticized polyvinyl chloride (PVC-U), polypropylene (PP), homopolymers and copolymers and to fittings made from these pipes. The dimensions and properties for thermoplastic pipes with profiled outer and smooth inner surfaces.

DIN 16961.2:2010-03 focuses on technical properties for profiled pipes made of PE-HD (high density polyethylene), PVC-U (unplasticized polyvinyl chloride), PP (polypropylene) homopolymers or copolymers.