Gas Welding & Heating Nozzles FAQs
Straight answers to the questions people ask most when choosing and using gas welding and heating nozzles.
What is the difference between welding, heating and brazing nozzles?
A welding nozzle gives a small, focused flame for melting metal and is sized for the thickness being joined. A heating nozzle gives a much bigger flame, often with many flame ports, for heating larger areas for bending, straightening, preheating or freeing seized parts. A brazing nozzle produces a softer, wider flame suited to heating the joint evenly without melting the parent metal.
Some heads are specialised, such as flame cleaning heads for removing scale and paint. Choose a nozzle for the job you do, for your torch and for your fuel gas.
How do I choose a welding nozzle size?
Welding nozzles are numbered by size. The number relates to how much gas flows, and so to how much heat you get and the thickness of metal you can weld. A small number suits thin sheet and a large one suits thick material. The numbering systems differ between makers, so do not assume a number from one maker matches another's.
Use the maker's chart for your nozzle, which gives the metal thickness and the pressures to use. A nozzle that is too small will not fuse the joint properly, and one that is too large can burn through thin metal or leave a messy weld.
Will a nozzle fit my torch?
Nozzles must match the torch they are used with. Torches differ in their connection, in the way they mix and feed the gases, and in the fuel gas they are designed for, so each torch has its own series of nozzles. Injector (low-pressure) designs and positive-pressure designs, for example, need different nozzles, and nozzle-mix torches use their own type too.
Check the torch maker's list for your model or the markings on your old nozzle. Do not force a nozzle that does not fit or mix parts from different makers, because it can leak or cause a flashback. If you are not sure, our team can help you identify the right one.
What are heating nozzles used for?
Heating nozzles put a large amount of heat into a wide area. They are used to preheat thick steel before welding or cutting, to bend or straighten bars, pipe and plate, to free seized nuts, bolts and bearings, and to warm or dry parts before work. Multi-flame heads spread the heat evenly instead of focusing it on a point.
Heat the metal slowly and evenly to avoid distortion and cracking, and remember that heated metal stays hot long after it stops glowing. Keep flammable materials away, and never heat a sealed or pressurised container or part.