 Many different energy sources can be used for welding , including a gas flame , an electric arc , a laser , an electron beam , friction , and ultrasound . While often an industrial process , welding may be performed in many different environments , including in open air , under water , and in outer space . Welding is a hazardous undertaking and precautions are required to avoid burns , electric shock , vision damage , inhalation of poisonous gases and fumes , and exposure to intense ultraviolet radiation . 
