A welding shroud or welding nozzle keeps the gas at the weld puddle:
A welding needle acting a very exact roll in the welding process. The major function of the welding needle or nozzle is to manage and direct the flow of the welding gases. It is most important to stay the nozzle clear from welding spatter.
Since any limit to the gas run will delay the welding torches presentation. A construct up of spatter on the inside of the welding needle will make turbulence in the gas direction. This turbulence will create the gas stream coming out of the needle out of control. Follow-on in not enough protecting gas about the welding arc. This means a fewer to wonderful weld.
Nozzles and shrouds are a welding consumable to turn into ineffective in excess of time. Frequently the ones so as to contain the white ceramic insulation fabric inside them such as the Bernard mig guns (WIA welding equipments) will finish up leaking air, and falling off. They require this air tight stick about the contact tip holder so that as the welding gas is flowing it does not suck in outer surface air similar to a venture result on a carburetor.