Weldless Ball Valve Install Issue

I am working on installing a weldless ball valve on my kettle and I am following Kal's, or theelectricbrewery.com and using their technique for attaching the valves. The issue is that the female compression fitting I got from Bargain Fittings will not tighten enough over the nipple to seal against the inside of the kettle.

Here is what I am trying to do. As you can see, the compression fitting should seat against the washer on the inside, but I probably have at least 1/8" before it would be tight. It feels like the threads are chewed up, but these fittings are brand new... To be honest, I'd say 90% of the fittings I received have nicks or imperfections from Bargain Fittings. But just by looking at these pieces, they don't look so damaged they wouldn't tighten.

I tried to tighten it outside the kettle and I'd say I can maybe get 2 full turns before it gets REALLY difficult to tighten, even with teflon and a little WD40 to try to help it turn easier.

I guess I just don't know what to do, whether the nipple just won't fit with the compression fitting for some reason, or maybe the threads are too damaged from shipping? Maybe would be worth contacting Bargain Fittings about it? Ugh, frustrating!!

My guess is the nipple is not NPT and the compression fitting is.
The electricbrewery links are to specific items at morebeer.
Those would probably work fine.

This problem has happened to me and was a factor pushing me to
welded fittings and tri-clamps. Almost completely converted and very happy.

It is not just Bargain Fittings. All of the vendors have this problem of not really
telling the customer what nipples work with what fittings. You should not
have to become an expert on NPT, FPT, MPT, bulkheads, etc just to put together
a SS weldless valve.

bob352 said:

My guess is the nipple is not NPT and the compression fitting is.
The electricbrewery links are to specific items at morebeer.
Those would probably work fine.

This problem has happened to me and was a factor pushing me to
welded fittings and tri-clamps. Almost completely converted and very happy.

It is not just Bargain Fittings. All of the vendors have this problem of not really
telling the customer what nipples work with what fittings. You should not
have to become an expert on NPT, FPT, MPT, bulkheads, etc just to put together
a SS weldless valve.

Click to expand...

That was my idea too! But the NPT lock nut fits over the nipple, and so does the ball valve, so if there was a thread difference it would probably be the compression fitting... But I have double checked my invoice and it says it's an NPT Female compression fitting

Who would have guessed screwing things together would be this difficult

Locknuts are NPS, no taper. Compression fittings off the shelf like those are NPT. There are just some variance in the actual OD of the threads. We're talking about thousands of an inch here. If the male side is slightly oversized and the female side is undersized, you only get a few rotations before the threads mesh. NPT was never meant to facilitate a gasket seal and we're really just doing the best we can. True bulkheads are expensive so people settle for this. What you need is an extra shim washer or two or a thicker gasket.

NPS is straight thread, no taper. NPT is the same general dimensions but the otherall OD of the threads is about the average of an NPT but just without a taper. You can usually mate male NPS with female NPT but not vice versa. MPT and FPT are just ways to denote Male/Female NPT.

Bobby_M said:

Locknuts are NPS, no taper. Compression fittings off the shelf like those are NPT. There are just some variance in the actual OD of the threads. We're talking about thousands of an inch here. If the male side is slightly oversized and the female side is undersized, you only get a few rotations before the threads mesh. NPT was never meant to facilitate a gasket seal and we're really just doing the best we can. True bulkheads are expensive so people settle for this. What you need is an extra shim washer or two or a thicker gasket.

NPS is straight thread, no taper. NPT is the same general dimensions but the otherall OD of the threads is about the average of an NPT but just without a taper. You can usually mate male NPS with female NPT but not vice versa. MPT and FPT are just ways to denote Male/Female NPT.

Click to expand...

So it would make sense maybe that the compression fitting is FPT but the nipple is maybe NPS? Or do I have that backwards...

Also, I tried to just screw in a male barbed fitting into the compression fitting, same issue. Will not get more than a couple turns out of it. So maybe the compression fitting would be the NPS?

Sent an email to Bargain Fittings to see what's going on. Hopefully they can shed some light on what's going on.

Actually what I was trying to say is that you have NPT threads on both fittings there but there are just some variances in OD. Obviously the female NPT on the compression fitting is a little undersized. At this point, shimming the gap with extra washers is practical.

Bobby_M said:

Actually what I was trying to say is that you have NPT threads on both fittings there but there are just some variances in OD. Obviously the female NPT on the compression fitting is a little undersized. At this point, shimming the gap with extra washers is practical.

Click to expand...

I gotcha... Well thanks for the response. I might try reconfiguring and if that fails, I'll shim it up.

BoxBrewer said:

I gotcha... Well thanks for the response. I might try reconfiguring and if that fails, I'll shim it up.

Click to expand...

On a positive note, shims have always worked for me.
Even when I only get a couple of threads to engage I can
get a leak proof seal with teflon tape.

The issue is as Bobby stated. NPT threads are tapered and you can get about half the threads to engage or about 1/4" total of thread. If the die / tap is worn or mis-set when they cut these nipples and females the threading can be too shallow.

I replied to you via email that we would get a replacement sent out.

The locknuts thread the entire length because they are NPS and slightly bigger than the male NPT threads.

Stainless steel shims are the way to take out the slack in any application like this.

BargainFittings said:

The issue is as Bobby stated. NPT threads are tapered and you can get about half the threads to engage or about 1/4" total of thread. If the die / tap is worn or mis-set when they cut these nipples and females the threading can be too shallow.

I replied to you via email that we would get a replacement sent out.

The locknuts thread the entire length because they are NPS and slightly bigger than the male NPT threads.

Stainless steel shims are the way to take out the slack in any application like this.

Click to expand...

What service! Thanks again!!

BargainFittings said:

Stainless steel shims are the way to take out the slack in any application like this.

Click to expand...

I got it and this compression fitting was MUCH better than the other one I got. I was able to get it fully tightened with only one extra shim on the inside of the BK. Thank you again!