PE pipes are flexible type plastic pipes made of semi-crystalline thermoplastic polyethylene (PE). PE the pipes are suitable for use in high pressure pipelines. Polyethylene pipes are used for the installation of pipelines in water, sewage or gas supply systems. PE pipes are divided  into pressure classes PN6, PN10, PN12.5 and PN16 according to the pipe strength, which is defined by the standard aspect ratio SDR. SDR = D / s, where D is the outer diameter of the pipe (mm), s is the wall thickness (mm).