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SkiprJohn · 17-04-2009, 13:30

Well! Here's my dilemma.

I ordered bronze 90degree street elbows and it turns out they are not NPT but NPS. Now I can't fit them to my 1" Jabsco saltwater cooling water pump because its NPT. This is so frustrating trying to get it right and dealing with companies from over the water and across the mainland. Its probably my fault for ordering the wrong item but I didn't see any options and didn't foresee the problem (dummy).

Question: Can they be made to fit?
If I find a plumber with a 1" NPT die could he turn them down for me?

Kind regards,
JohnL

btrayfors · 17-04-2009, 13:55

If you can possibly wait, I'd order the proper fitting rather than try to make something work (silk purse out of a sow's ear???).

Here's a source: Pipe Fittings and Bronze Pipe Adapters / Connectors

No doubt there are many others.

Be sure to consider not only the NPT fitting for the pump, but what you're gonna attach to the 90-degree fitting: NPS, NPT, hose????

Also, a street elbow ain't as good as a more gently curved 90-degree elbow....if you have room.

JMHO.

Aloha,

Bill

SkiprJohn · 17-04-2009, 16:46

Thanks Bill,
I guess I'll have to bite the bullet on this one.
Darn.
JohnL

SkiprJohn · 17-04-2009, 16:50

Since this is a new installation I'll just make room.
JohnL

Celestialsailor · 17-04-2009, 20:49

John....An unusually large hammer normally works...

Lancerbye · 17-04-2009, 21:50

John

Unfortunately if the error had been the other way you could have solved it by re threading with an NPS tap and Die. However you need the tapered fitting. The threads should be the same if you have the exact match and have not got metric mismatch also. The NPS = National Pipe Straight and NPT= National Pipe Taper. I have seen people use them together with lots of teflon tape but it's not a good seal. I know the price you paid for those bonze fittings is not easy to swallow but.....

delmarrey · 17-04-2009, 23:35

Where in the heck did you get a bronze street elbow with a NPS thread? And what makes you think it is a straight thread? I've only seen NPS on hydraulic elbows only.

BTW- one can screw a straight thread in to a tapered using a sealant but not the other way around. A tapered hole will crush the male fitting a bit but a tapered thread in a straight hole would go up to the last thread and probably not seal except on the last thread.

http://www.sintermatic.com/pdf/t2.pdf

In the chart above, if you look at the thread pitch dia's (e.g. 1") you will see the pitch dia at the E1 (1.238") of the female tapered thread is the same as the pitch dia of a straight thread. One would have to force it in a little bit but is would hold and seal at typical pipe pressures. Just use RecterSeal #5. See the first line of the last page.

......................................_/)

SkiprJohn · 18-04-2009, 12:55

Aloha Del,

Got them from Hamilton Marine at www.hamiltonmarine.com under their plumbing section listed as bronze plumbing. I guess I should have assumed they were straight unless they are listed as tapered?

Thanks for the info. Its good to hear I might still be able to use them.

Regards,

JohnL

Lancerbye · 18-04-2009, 19:11

Hey JohnL
You were right in assuming that the fittings were a tapered thread. That is a much more common thread in North America. I looked at the site for Hamilton and I think they made the mistake. Your fittings on the main page in the size you got look like BPSS (British Pipe Standard Straight) which are again different than NPS or NPT just to add confusion to the pot. Out here in the Middle East we have nothing but piping screw ups when it comes to pipe fittings. On Hamilton's pages I see Both types of fittings and changes from the page view to the expanded view. BSPP (British Pipe Standard Parallel) normally have a hex nut fitting which allows the use of a wrench on a fitting as is shown on some of their fittings. NPT are usually made to be used with pipe wrenches. I deal alot with various types of fittings and I have seen exceptions to all norms, so it comes as no surprise that you did not get what you really wanted. There are too many standards. The way they presented the advertised fittings, the discriptions were not detailed enough.