need help identifying threads 1

[packmule]

Had to replace nozzles on steam jets recently and one of six gaulded while trying to unscrew it. Of course, the internal threads were damaged so I figured the simple thing to do was head to the machine shop and get a tap to clean up the threads. One problem..... upon measuring the major dia. of the nozzle threads I found to be .808 or 20.5mm. I didn't bother checking the pitch because I realized instantly that I had an odd size and there is probably not a tap that size in the state. I couldn't find any info on threads this size in the Machinery's Handbook. Could this be special made for this application only? The nozzles screw into sch.80 pipe but they are straight threads, whether or not they are considered straight pipe threads or machine threads I don't know.

 

[mrainey]

Maybe a 1/2-14 NPSM? The major runs .813/.823


Software For Metalworking

http://mrainey.freeservers.com

 

[packmule]

You were correct, it is a 1/2-14 npsm. We found a tap locally and cleaned up the threads and welded a bead around the nozzle for safe-keeping.

Thank you.

Greg