Thread: Groco seacock
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Old 09-10-2015, 10:41 AM   #20
ranger58sb
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City: Annapolis
Vessel Name: Ranger
Vessel Model: 58' Sedan Bridge
Join Date: Aug 2013
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Quote:
Originally Posted by TDunn View Post
So if some Buck Algonquin phone guy told you their valves have straight threads on the input end all I can say is that their technical specifications on the web site say the valves are all 100% tapered (NPT) threads.

It was during a phone conversation, where I had asked pretty much the same questions... and partly because of the specs on their website.

He didn't say their valves have straight threads, though; he said their NPS thru-hull threads are "slightly modified" to work better with NPT ball valves. (Backwards from the way I said it before; sorry, just re-read my notes from back then.)

This from a note I posted (on another forum) shortly afterwards (11/7/2011):
Another tidbit I just learned today...

The very helpful sales assistant at Buck Algonquin told me they've machined the NPS threads on their thru-hulls in a way that allows them to accept an NPT-threaded ball valve. He said to expect approximately 3 turns before the threads lock up, with Teflon tape recommended as the pipe sealer.

He also said he thinks all thru-hull manufacturers do the same -- and that seems to jive with what Groco describes as "combination threads" on the ends of their NPS-threaded through-hulls.
At the time I thought it made absolutely no sense at all for companies to make ball valves with NPT threads intended to mate up with NPS thru-hulls. Since then I've come to suspect they assume their marine ball valves will be used in a number of different applications where NPT threads would be appropriate... and have maybe adopted this kind of approach simply because ONE of those applications (probably relatively low volume, marine thru-hulls) would mean mating NPT-NPS threads. IOW, cost control for the manufacturers, too, not just the boat builders.


-Chris
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