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Stuck NPT fittings
Posted: Mon Jan 22, 2007 8:44 pm
by snowjack
Probably a noob question. I'm almost done building my first gun, but I'm having trouble with the threaded fittings. The male fitting is NPT Sch80 PVC, and the female fitting is NPT Sch40 PVC (this is for a combustion gun, I couldn't find the male fitting I needed in Sch40). Anyway, I can't get the male fitting to go in all the way. It gets tighter as it goes and gets stuck about 2/3rds of the way in. Both the male and female are supposed to be tapered threads according to McMaster (straight is NPS instead of NPT, right?). On Burnt Latke's site he recommeded filing down the little imperfections in the thread seams, but that doesn't seem to have helped. I also tried lubricating the threads with a little WD-40 but that didn't help either. Any suggestions?
Posted: Mon Jan 22, 2007 8:48 pm
by squeaks
hahahahaha............sorry, had to laugh at this one.
NPT fittings are supposed to get tight until the point where you can't turn them anymore. This is so that a proper seal can be acquired. It's perfectly fine to have some of the threads not being used. Just remember to teflon the threads.
Posted: Mon Jan 22, 2007 8:54 pm
by Bluetooth
Yeah, if you get it all the way in your not getting it back out. Lol
Posted: Mon Jan 22, 2007 8:57 pm
by garrettee
Take it easy squeaks, If you knew it all when you started you wouldn't be here right now. That's what this forum is for, right?
Posted: Mon Jan 22, 2007 8:59 pm
by MrCrowley
2/3rds aint bad, if it blows off dont blame us
Posted: Mon Jan 22, 2007 9:24 pm
by squeaks
I was taking it easy. That's why I was enjoying this moment for some comic releif. Yeah, I knew about just as much when I first started. Then I discovered the joy of the forum search key and spudwiki. Two lifesavers.
Posted: Mon Jan 22, 2007 11:34 pm
by snowjack
squeaks wrote:I was taking it easy. That's why I was enjoying this moment for some comic releif. Yeah, I knew about just as much when I first started. Then I discovered the joy of the forum search key and spudwiki. Two lifesavers.
No harm, no foul. But just for the record I did spend about an hour searching the forums, reading, and going through the Wiki, and didn't see anything mentioned about stuck threaded fittings.
Actually, all together I've probably spent three or four hours reading through the forums here, and I think I saw more posts about forum etiquette, grammar, and spelling than about spudguns...
Anyway, thanks for the sanity check, everybody.
Posted: Mon Jan 22, 2007 11:45 pm
by squeaks
Yeah, we are a bit nutz here about grammar and whatnot. In fact, just by typing this message someone will proofread me and fix any and all spelling/grammar errors. That or they will make fun of me for whatever dumb reason I'm posting this message. That's half of the fun of the forum.
Posted: Tue Jan 23, 2007 12:07 am
by A-98
ugh. you spelled "nuts" wrong!!!
lol, jk
ya, when i first started i thought that you had to get them almost all the way in...but then i realised that that wast possible.lol.
Posted: Tue Jan 23, 2007 12:16 am
by Pete Zaria
Snowjack,
Two strap wrenches (like these:
) work wonders on stuck threaded fittings.
I don't know if they'd shrink at all if you put them in the freezer to get them cold - it might help, and I don't think it could hurt them...
Peace,
Pete Zaria.
Posted: Tue Jan 23, 2007 11:32 am
by snowjack
That should work. Thanks, Pete!
Posted: Tue Jan 23, 2007 2:00 pm
by jrrdw
Helpfull hint --
After you get it out of the freezer, try a hair dryer on the out side of the female fitting, that will make it even easier to unscrew.