The principle of heat fusion is to heat two surfaces to a designated temperature,then fuse them together by applicaon of a sufficient force. this force causes the melted materials to flow and mix, thereby resulng in fusion. When fused according to the pipe and/or fing manufacturer's procedures, the joint area becomes as strong as or stronger than the pipe itself in both tensil and pressure properties. As soon as the joint cools to near ambient temperature, it is ready for handling.