Tape or Tighten ?

admin

Hi Folks,Glad I found this place.   I own a circa 1995 craftsman MIG welder (Lincoln elect made it I believe).It has thin, roughly 1/8 plastic tubes that carry the argon.  Thus, my regulator has a special quick-release adapter for that 1/8 plastic hose.    Okay...Okay....I admit, those quick release do-hickeys arent industrial per se, but its a darn good little welder and serves our shop just fine.     So when we broke the old quick release adapter ....and still found a cache of those quick release things, I was greatly relieved.   I also bought a new regulator.However Im still finding that my new regulator is leaking gas after I get past ' 5 ' (psi I guess).  I cant seem to tighten the nuts any tighter.   I guess my question boils down to this....Should I use that white tape stuff to seal off anything?And where can I buy that white sealant tape?Or, could something else be causing the leak?Projects are backing up...I gotta get this thing working again.   Thanks folksDrew
Reply:Many of the readers here are neither familiar with your machine, nor your gas set-up. Either a very detailed description, or better yet, some good pictures of the equipment, would provide the information that is needed by us  uninformed ones to give you a reasonable response.
Reply:it is called teflon tape , sold where home plumbing stuff is sold.but first get some soapy water on that thing to find out where its leaking.
Reply:General rule: tape is only used on tapered pipe threads, and is intended to lubricate the threads to allow proper tightening without galling to get the seal. It is not itself a sealant.It should not be used on standard regulator fittings (attachment to the bottle), standard hose fittings, quick connects, etc, as these do not seal on the threads. The quick connects seal using an O-ring, the others seal on a ground seat.If the connection you are talking about is the style I am thinking of (the bare plastic hose pushes in to the connector, and you push a collar to release it... I have never seen these on welding gear, but use them for vacuum and control air, and they were all over the lab for service gasses when I was doing semiconductor fab work), tape won't help if the leak is on the hose. The only solution is to cut the hose back about 1/4" (or as needed to get clean, smooth surface), and if that doesn't fix it, replace the connector. If, and only if, the leak is where the connector is threaded into the flow regulator, and the threads are tapered pipe thread, then it may be removed, and after inspecting the threads for damage, and reinstall with teflon tape. Be very careful to keep the tape back from the lead thread, and to wrap it the proper direction. If you let a little flake get into the system, you will have a devil of a time.
Reply:Here is a photo of the piece that is leaking.I have another thread regarding how to remove it.   Both related in a sense, but ultimately taking different routes. Attached Images
Reply:Is that the fitting which came installed on the regulator? If so, it should have the correct thread; it appears to be  a 1/4" pipe thread  which is commonly used there. I would remove the fitting and see if the internal thread appears to be deep enough, the correct thread pitch, and properly formed---sometimes factories do make mistakes. If it does look correct, then the Teflon tape should be usable, as stated with the cautions above. I generally use 1.5 to 2 layers of the thin material, (I'd guess it is maybe 1/1000" thick, and I do have some which feels 3 to 5 times thicker) rolling it into the threads with my finger. Because Teflon lubricates well, the fitting is easy to over-tighten so be careful when assembling.
Reply:OldironThe hose fitting actually comes off.   Thus the red circled coupling has threading to the left (covered by the hose fitting), a nut, and then threading to the right).  Ergo,   the coupling is a solid unit composed of:  threading- nut portion- threading