Decoding the welding fittings…

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.

These are the standard fittings (using part numbers from Western Enterprises) that you may need while working on your oxygen and/or fuel gas lines:

Hose Nuts:

 Hose Nuts 

  • Oxygen Part # 7
  • Fuel Gas Part # 8

 Nipples (can be used with both oxygen and fuel gas)

 Barbed Nipples

  • 1/4″ ID Hose Part # 17
  • 5/16″ ID Hose Part # 216
  • 3/8″ ID Hose Part # 20

Regulator outlet bushings (NPT to “B” fittings)


  • 1/4″ Male NPT to RH B Part # 32
  • 1/4″ Male NPT to LH B Part # 33
  • 3/8″ Male NPT to RH B Part # 142
  • 3/8″ Male NPT to LH B Part # 143

Hose Couplers

 House Couplers

  • Oxygen RH Part # 30
  • Fuel LH Part # 31

Male B fitting to hose adapter


  • RH B to 3/16″ ID hose barb Part # 40
  • RH B to 1/4″ ID hose barb Part # 40-B
  • LH B to 3/16″ ID hose barb Part # 41
  • LH B to 1/4″ ID hose barb Part # 41-B

I gratefully acknowledge the wealth of information available on the Western Enterprises website:

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