ISO 4427-3:2007 specifies the general aspects of fittings made from polyethylene (PE) for piping systems intended for the conveyance of water for human consumption, including raw water prior to treatment and water for general purposes. It also specifies the test parameters for the test methods to which it refers.

In conjunction with the other parts of ISO 4427, it is applicable to PE fittings, their joints, to joints with components of PE and to joints with mechanical fittings of other materials, intended to be used under the following conditions: a maximum operating pressure (MOP) up to and including 25 bar; an operating temperature of 20 °C as the reference temperature.