There are three types of conventional heat fusion joints currently used in the industry: Butt, Saddle, and Socket Fusion. In addition, electrofusion (EF) joining is available with special EF couplings and saddle fittings. The heat fusion process comprises the heating of two surfaces to a designated temperature, followed by application of a sufficient force to cause the melted materials to flow and mix, thereby resulting in fusion of the two components. When fused according to the pipe and/or fitting manufacturers' procedures, the joint area becomes at least as strong as the pipe itself, in both tensile and pressure properties, and properly fused joints are absolutely leak proof. As soon as the joint cools to near ambient temperature, it is ready for handling.