Welding can easily defined as process for joining different materials whether they are made of the same or different kinds of metals. Though this process is mostly used to join metals and their alloys it is also used to join different kinds of thermoplastics. The welding process consists of a number of processes in which the materials to be welded are joined together by the application of heat.As early mentioned the most essential element for this joining process is heat. Without it welding cannot be done. There are many types of Plastic pipe welding machine. In some methods the application of pressure is also essential. It is one of the most used processes in manufacturing whether it is cars, planes, electronic equipments or anything solid. Welding was invented in the early 1900's and played a big role in post industrial revolution.Welding processes are classified into:Gas welding: This is the most used method of joining metals in small-scale industries. Here a mixture of Oxygen and Acetylene is burned to attain the high temperature required for the process.Arc Welding: here the heat required for melting the metals is generated by means of an electric arc. The most commonly used arc welding method is TIG (Tungsten Inert Gas).Resistance Welding: In this process the heat required to melt the material is obtained though the resistance offered by that material to the flow of electric current.Advantages:A good joint created though this process is as strong as the base metalGeneral welding equipment is not so costlyPortable welding equipments are availableWelding permits considerable freedom in designA large number of metals/alloys both similar and dissimilar can be joined by welding