HDPE pipes are also available in 63 to 450 mm in PN 2.5, PN 4, PN 6, PN 8, PN 10, PN12.5 and PN 16 pressure class. These pipes are manufactured as per IS 14333:1996 and are available in 6 meter length. The pipes are joined either by click ring type fittings or by butt welding, thus absolutely watertight. These pipes are most advantageous for undulating terrains.