Steel can only be field/shop fusion welded with O/A and electric arc. Carbon arc and forge welding demised a long time ago. In the case of O/A it has to do with carbon provided by the acetelene. There are other process used in a production mode but they are not field feasible. A substitue for Acetelene as a fuel has never been found. The terms "weld" and "braze" are not interchangable. Weld is a fusion process, braze is a soldering process using high temp alloys, penetration is a capillary penetration process involving only the material surfaces.
I have had excellent results using propane or natural gas as a combustible fuel mixed with O2 for heating, brazing/soldering, and cutting of steel. Standard acetylene tips and rosebuds work with other fuels only steel cutting requires a special tip. I modified my tank cart to also hold a propane tank. The acet regulator works fine but requires an adaptor to the tank outlet of propane. Make sure your twin hose is propane certified, older hoses are not and will break down rapidly.
I predict the demise of acetylene due to production cost as demand declines and O/A tecniques become rare. O/A welding is not taught much anymore. What we used to O/A butt weld is now done with with arc using socket weld fittings (smaller pipe). I was always a better O/A welder than arc welder although certified on pressure vessels/power piping for both. Even know well and have used acetylene generators.
Now I have dated myself, Ron
