NPT / IPS

[jughead]

I am installing a Moen shower spout. The spout has iPS threads. The brass nipple has to be exactly 6 3/4" long. Since the nipple threads are NPT on both ends cutting either or both ends to achieve the correct length will not work because of the taper. If I could find a nipple with NPT on one end and IPS on the other, I could cut the IPS side so that it would be the proper length, but I cannot find a brass nipple that has NPT on one end and IPS on the other. How do I solve my problem ? I have brass nipples in lengths of 6 1/2", 7 ", and 7 1/2", but they all have NPT threads. Help please. Thanks.

 

[Jeff Handy]

If you add a few extra wraps of teflon tape to each end, then a 6 1/2 inch long nipple will tighten up early at each end, and should work for you.

Or use two shorter nipples and a coupling, with teflon tape, and after some trial and error you will find the right combination of nipples that gets you the length you need.

 

[breplum]

There are lots of great spouts that have easily adjustable depth capability. We routinely reject any spout that doesn't allow good adjustability.
Most Grohe spouts have this flexibility. Same with the Delta line.
And, I have not ever been aware of a spout having straight threads.
They all use standard taper threads. The only place we ever see straight running threads are the shank for the tightening nut on toilet ballcocks and sinks and washing machine box valves to secure to the fixture.
Abandon that Moen spout. Even Pasco makes easy adjust diverter and non diverter spouts

 

[jughead]

Thanks for the suggestions. I tried loading up extra tape with the 6 1/2 nipple and was sure that it would work, but strangely, it didn't work. I don't think I have enough inside diameter in the spout (it's a narrow barrel, which is why I bought it) to use a coupling. After thinking about it overnight, I think what I will do is cut the 7 1/2" nipple to 6 3/4, then use a die and cut NPT threads on the cut end, and use a lot of tape and force it in. I don't think I have an IPS die but if I do, then obviously I'll use that instead. Normally, I'd just use another spout, but I like the looks of this one, so I guess it's worth going the extra mile. Thanks much for your suggestions. I may end up using the coupling and grinding it down since I've only cut threads on galvanized pipe before and am not sure if the brass will cut as well (I assume it will, since it's much softer). We'll see.
Mahalo!

 

[jughead]

There are lots of great spouts that have easily adjustable depth capability. We routinely reject any spout that doesn't allow good adjustability.
Most Grohe spouts have this flexibility. Same with the Delta line.
And, I have not ever been aware of a spout having straight threads.
They all use standard taper threads. The only place we ever see straight running threads are the shank for the tightening nut on toilet ballcocks and sinks and washing machine box valves to secure to the fixture.
Abandon that Moen spout. Even Pasco makes easy adjust diverter and non diverter spouts
View attachment 25571

 

[jughead]

I hear ya, but I really like the looks of this spout. Even the box says IPS on it. Actually, that isn't the main issue. I can live with using a lot of teflon tape and mating the NPT to the IPS, it's the length of the pipe that is the issue. If I cut the 7" pipe at one end so that it's 6 3/4, since (I measured it) the pipe only screws into the diverter about 1/4", I expect that if I cut the tapered threads, the diameter of the shoulder of the taper will just barely grab onto the IPS threads and the joint will be barely hanging on. I'm going to find an old 1/2" pipe with NPT threads and will experiment and if it does grab enough to avoid a leak, then I'll just cut the pipe; however, I think the cut diameter of the threads will be too large to allow the nipple to fit into the diverter. I expect that I'll be better off trying to cut new threads as outlined in my reply to Mr. Handy. But I will try just cutting the NPT threads and see if that will work.
Thanks much.

 

[jughead]

I experimented and cut 1/4" off the NPT threads; as expected, it will screw into the IPS spout, but will only go in about 2 revolutions which is probably 2 or 3 threads, so it would just be hanging on and would more than likely leak. I did find both male and female NPT to IPS adapters at McMaster-Carr Plumbing, the cost of the adapters was $3 to $4.00 but the shipping to Hawaii was $24.00 each, so that's just ridiculous; but, they do exist. In any case, I could not find my taps and dies, so I've ordered a 1/2" die and that should work just fine, once I cut the pipe to proper length. I know this sounds silly and a lot of work for a simple diverter, but I'm building kind of a special shower and if I'm going to do it, I'll do it "right". I've attached some photos just to let anyone who reads this to know that I'm just a DIYer, just trying to do my best. Thanks much to Handy and Breplum for your response. Aloha.