Using polyethylene fittings and valves in water and gas industry is a common and necessary approach nowadays. The chemical and physical properties of polyethylene on one hand, and increasing expansion of gas and water and sanitation networks in Iran on the other hand, has made the use of these products inevitable. Over the past 15 years, the use of Polyethylene Electrofusion fittings and valves has been a priority in all the gas projects executed by NIGC.