Processes and Hazards
Welding
Welding is a general term for various processes used to join metal parts by producing a coalescence, known as a weld, at a joint. This is usually accomplished by applying heat and energy while bringing the pieces of metal together.
Welding has numerous applications. Some welded products include ships, aircraft, automobiles, electric and electronic parts, and in building and construction work. Although more than 50 welding processes are used today, the most common are gas welding and arc welding.
Welding is a hazardous process that joins materials together by melting a metal workpiece and a filler metal to form a strong joint.
Coalescence
Coalescence occurs when two metals seem to pull together or merge into one body at the base metal parts upon the slightest contact. There are two basic requirements for coalescence: heat and intimacy of contact.
Heat
Welding processes differ depending on the source of heat, how heat is applied or generated, and the intensity of the heat. The fuel used as a heat force may be:
- acetylene or hydrogen in air or oxygen;
- an electric arc;
- an electric, gas, or oil furnace;
- the resistance of metal to the flow of electric current; or
- a chemical reaction between a metal oxide and finely divided aluminum.
The intensity of heat applied or generated at the joint varies according to the metals being joined and the welding process used. All welding processes, except brazing, use temperatures high enough to melt the base metals. However, all welding, cutting, and brazing processes generate enough heat to injure workers seriously.
Intimacy of Contact
The second basic requirement for coalescence, the intimacy of contact, is accomplished in two ways: pressure processes and non-pressure processes. In pressure processes, there is no space between the surfaces being joined. Welders apply pressure while the contact surfaces are at a high enough temperature to allow the plastic flow of the metal. In non-pressure processes, the space between the joined surfaces is filled with molten metal.
Knowledge Check Choose the best answer for the question.
1-1. Why does welding create a potential serious hazard to workers?
You forgot to answer the question!