Air fittings won't screw down

[dragginmetal]

My fittings will only go about 1/3 of the way down. Is this normal? Seems like it should tighten more than 3 threads. Should i get a thread cleaner? Its all new parts. ...any ideas?


It looks and feels like the threads are flat inside the bung.



1/4" seems to be fine

[N2TRUX]

Anyone?

[dragginmetal]

Hey, thx for the bump. .........

My concern is, will 3 threads hold 150-200psi? Its a new tank so if i use a thread cleaner and it dont work then i probably void any warranty on the tank. I dont want to ship the tank back if the threads just need to be cleaned.

[gringoloco]

I would run a tap through, but NPT threads are tapered. This means they may not sit flush but still be tight. 2-3 threads is not enough IMO, hence the need to tap

[Shane]

"chase" the threads with the correct NPT tap (DO NOT USE A STANDARD TAP!!!) ... run the tap in by hand until it's snug then turn ONE revolution with a wrench ... back it out ... test your fitting ... repeat until at least 1/2 - 3/4 of the threads are fully engaged.

~ use just enough Teflon tape to cover the threads with 2 layers of tape. more tape doesn't mean more seal.
~ don't be afraid to use some grunt on it
~ NPT threads are designed to deform in order for the "mechanical seal" to work correctly
~ the brass is softer than the steel so you'll only be out a fitting if you over-tighten
~ bow-up on it and let us know how it turns out

[71swb4x4]

New parts are not always good parts. I think one of three things is happening:
1) The threads on the tank are messed up.
2) The threads on the fitting are messed up.
3) The fitting is not NPT thread. Maybe you bought NPT thread, but maybe the wrong fitting was in the bin when you or the person you ordered it from pulled it.

I would run to the hardware store and buy another fitting. It doesn't have to be a correct fitting, just the correct threads - throw another in and see if it seats farther. That would at least tell you if the problem is your fitting or your tank bung.

[Shane]

the fitting in the provided pic is indeed an NPT thread fitting.

[dragginmetal]

Thanks for posting and helping me out yall.

I have tryed other fittings. They all did the same thing. So im thinking it the bung, or should i say all 6 of them (6-1/2",3-1/4"). All the 1/2" are like this. Seems like the bungs shrunk when they were welded to the tank, or something like that.
I'll get a tap tomarrow and go from there. I'll let yall know how it goes... also this tank is aluminum if that makes any difference.

[tubbedII]

The bung's 1st 3 threads looks stripped...they look further apart than the last 4 in the pic, but that could be my eyes playing tricks on me. Shane's response sounds to me like your best option at the moment (getting a NPT tap).

[dragginmetal]

Originally Posted by tubbedII

The bung's 1st 3 threads looks stripped...they look further apart than the last 4 in the pic, but that could be my eyes playing tricks on me. Shane's response sounds to me like your best option at the moment (getting a NPT tap).

I just went and checked. I think its the anodizeing comming off the threads. The dark lines are the peak of the treads. The brass fitting is trying to cut the threads deeper. On the brass fitting i can see where its flattening the threads but they still look evenly spaced.

[fixit-p]

Be careful that your not trying to put a NPT fitting into an SAE port, it's hard to tell from the pictures if that's what you have or not. Is there a chamfer before the threads begin on the tank flange? If yes you may have a 1/2" SAE flange which has a 3/4-16 straight thread and will not accept NPT fittings.

[kev2809]

where did you get that tank from?

[dragginmetal]

Originally Posted by fixit-p

Be careful that your not trying to put a NPT fitting into an SAE port, it's hard to tell from the pictures if that's what you have or not. Is there a chamfer before the threads begin on the tank flange? If yes you may have a 1/2" SAE flange which has a 3/4-16 straight thread and will not accept NPT fittings.

I'll have to check that.

Originally Posted by kev2809

where did you get that tank from?

AVS.

[Shane]

Not 100% on this, but I don't think SAE fittings are approved for pressure vessels.

[fixit-p]

Originally Posted by Shane

Not 100% on this, but I don't think SAE fittings are approved for pressure vessels.

Yeah I see allot of them on class 8 trucks, not saying that's what the op has here but I work with fittings on a daily basis and the first thing I do is identify what I have.

[dragginmetal]

Originally Posted by fixit-p

you may have a 1/2" SAE flange which has a 3/4-16 straight thread and will not accept NPT fittings.

Does that mean a standard bolt will tread into it? I dont know how to tell a SAE from a NPT.

[fixit-p]

Yeah if it's SAE a regular bolt will screw in. 1/2" SAE is a 3/4-16 thread and a 3/8" SAE would have a 9/16-18 thread.

[dragginmetal]

OK, here's where i'm at. I went to Tractor Supply, Atwoods, Autozone, Oreillys, True Value, and a Ma and Pop hardware store. No one had a tap that big or could identify 100% what the threads are in the tank. I ended up at a Fastenal store. They said the tank threads were M20-1.5. The adaptor to go from them threads to 1/4" is around 10 bucks apiece. I need 6 of them. So, im just gonna ship the tank and fittings back and let them send me something that works... Thanks for all the help everybody. I do appreciate it.

[texastrendz]

See if you can buy an American built steel tank. Should not have issues then.

[tubbedII]

Man, that sucks...good luck with the next one!

[fixit-p]

Metric, that stinks. I just had a Volvo truck in the shop the other day I assumed the fittings were SAE (o-ring boss) but I bet it was metric too being a Volvo.

[lolife99]

Did you try to run a NPT tap thru it?
I have a hard time believing any air ride company would put a metric bolt thread in an air tank. All of the ports should be a tapered pipe thread.

I think the welding process and the paint/coating are the issues.
The NPT thread pitch may be similar to a metric bolt thread, but I would try a pipe thread tap first.
Posted via Mobile Device

[fixit-p]

Originally Posted by lolife99

The NPT thread pitch may be similar to a metric bolt thread, but I would try a pipe thread tap first.
Posted via Mobile Device

Interesting point, I checked the thread pitch on a 1/2" NPT fitting which is 14 TPI and is no where close to 1.5 MM. If you were to take a pipe tap to it you may end up with interrupted threads and it will possibly leak. I would check with your vendor, they probably have more tanks with similar issues.

dragginmetal did Fastenal actually thread a M20-1.5 bolt into that port?

[SCOTI]

Originally Posted by fixit-p

Interesting point, I checked the thread pitch on a 1/2" NPT fitting which is 14 TPI and is no where close to 1.5 MM. If you were to take a pipe tap to it you may end up with interrupted threads and it will possibly leak. I would check with your vendor, they probably have more tanks with similar issues.

dragginmetal did Fastenal actually thread a M20-1.5 bolt into that port?

I agree. Check w/AVS on what the thread pitch should be & see if there have been other issues brought to their attention.

[dragginmetal]

Originally Posted by lolife99

Did you try to run a NPT tap thru it?
Posted via Mobile Device

No, Nowhere i went had one that size.

Originally Posted by fixit-p

dragginmetal did Fastenal actually thread a M20-1.5 bolt into that port?

They threaded a "thread finder(?)". It was a bunch of different pieces of pipe on a wire string conected together. One side was male the other female on each of the pieces.. I dont know the proper name for this tool.

Originally Posted by SCOTI

I agree. Check w/AVS on what the thread pitch should be & see if there have been other issues brought to their attention.

I called them yesterday. They said to mail them the tank and they would look at it and go from there.......... On a side note. I may be out of luck. I ordered this stuff around march and just now had time to install it.