We have talked a lot about “B” fittings on regulators, hoses and other parts, but what does ‘”B” fitting’ really mean?
In simple terms, the Compressed Gas Association (CGA) standardized fitting sizes some years ago. These fittings follow specific size and thread designs, and consist of “A”, “B”, “C” and “D” sizes. The welding industry for the most part uses “B” fittings, so those are the ones we will be discussing here. Also standardized is that oxygen fittings have right hand threads and fuel gas fittings have left hand threads. Fittings designed for use with fuel gas will also have a notch machined into either the nut or hex fitting.