some kinds of welding do not use an electric arc. they might use a flame, electricity without an arc, an energy beam, or physical force. the most common type of welding that does not use an arc is called gas welding. in gas welding, a flammable(meaning it will burn) gas and oxygen are combined and burn at the end of a torch. gas welding does not need any special shielding because a flame which is adjusted right has no extra oxygen in it. it is still important to make sure the metal is clean. the flame heats up the metal so much that it melts. when both the pieces of metal are melted at the edge, the liquid metal becomes one piece.