During the early years of welding and cutting apparatus development, there was no uniformity among manufacturers of torches, hose connections and regulators. In order to use one manufacturer’s torch with another manufacturer’s regulator, an adaptor had to be inserted to make the connection, or hose connections had to be changed entirely. In a cooperative effort, the equipment manufacturers developed a set of standards which were approved by the Gas Products Association (no longer in existence) and the International Acetylene Association. These standards have been in use since 1926. They were also adopted by the National Screw Thread Commission of the Bureau of Standards
(now the National Institute of Standards and Technology), Washington D.C., as Standard No.107.
Threads for the hose connections for small torches are 3/8 in. O.D., 24 threads per in., left hand for acetylene and other fuel gases, and right hand for oxygen.
Threads for ordinary size torches and for regulators are 9/16 in. O.D., 18 threads per in., left hand for acetylene and other fuel gases, and right hand for oxygen.