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Old 09-10-2014, 11:30   #16
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Re: Tapered fittings on thru hull question

If you look at the picture, the OP's issue is after the valve. It's really likely that it's 1/4" NPT threads, because wouldn't NPS be super rare to be used there? I don't even know where I'd get 1/4" NPS fittings.

So, in my mind It's still a simple issue of there's no more threads to turn the T on because it's been over tightened. OTOH, if they WERE NPS, that's exactly what would happen.

Easy enough to tell if you pulled the T off and looked for a taper.

Reread a bit and found:
Quote:
Originally Posted by robert sailor View Post
Yes there is a ball valve on the thru hull and the elbow screws into the the ball valve fitting. They both look like tapered threads.
That gives a bit of credence to the fact that they're NPT. Jamestown has the T and the street el in bronze for around $4 each. Seems the easy way to fix it without changing the seacock, or resorting to goop.

(I agree that the thru-hull is NPS, and that NPT should not be threaded onto NPS)
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Old 09-10-2014, 11:56   #17
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Re: Tapered fittings on thru hull question

take it apart and determine if the fittings are not bottoming out etc. Clean the threads or replace any fittings that don't match well (bottoming out). BE SURE TO USE MULTIPLE WRAPS OF TEFLON TAPE or P J compound. You can use 5200 there is no problem getting metal fittings apart with 5200.
and finally... remember pipe threads have to be REALLY tight.
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Old 09-10-2014, 14:37   #18
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Re: Tapered fittings on thru hull question

Its a forward bilge pump that would rarely ever be used as it picks up water out of the chain locker and the shower sump pump which is never used. The water would enter the thru hull when we were sailing but was stopped by 2 check valves off of each line but then it would leak with a steady drip and that drip would turn into gallons after several days/nites at sea. I could not isolate the leak as the fitting was wet and was dripping, hard to tell exactly where it was coming from so decided to take the whole thing apart and clean everything up and replace it. Problem is that whenever it was originally installed some sort of pipe lock was used as it was a bugger to remove but that was probably how they were able to center the elbow even though it wasn't tight. I'm no plumber but it feels like the elbow does bottom out in the ball valve. After we found the source I simply shut off the ball valve and that stopped our water problem but I don't want to not have the lower chain locker pump not working when we cross the Atlantic. I'm going to make a trip to the local hardware store in the morning and see if I can buy some replacement fittings. Thanks for all the ideas and suggestions/advice. Cheers, Robert
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Old 09-10-2014, 14:46   #19
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Re: Tapered fittings on thru hull question

Never install a check valve in a bilge pump line.

Never share a bilge pump line.

And don't expect to find bronze fittings at the local hardware store. Don't use brass!
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Old 09-10-2014, 15:04   #20
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Re: Tapered fittings on thru hull question

Someone mentioned the elbow had bottomed out and maybe I'm getting old or just didn't notice but I flipped the elbow (even though I carefully put everything back together the first time exactly the way it came off) and the one side had a little more thread and that allowed the elbow to center being tight. It needed a wrench to turn the last 180 degrees, which was just perfect. The T portion also went on pretty tight so I'll put all the hoses back together in the morning and double clamp everything and wrap it in paper towel so that if it leaks even a little I will see it. Hopefully that looks after it. We have an overnighter to the next Island in another few days and that will be a good test. Thanks again for all of your impute...much appreciated.
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Old 09-10-2014, 17:50   #21
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Re: Tapered fittings on thru hull question

It's good you appear to have solved the positioning problem.

Earlier, Donradcliffe suggested Loctite 242. I have used this before to secure a fitting in a position where it was still loose on the thread. Works fine and (apparently) it can be released with heat, as it melts. I thought the price was reasonable at around $20 or so for a small tube from memory.

I also used it to secure an engine control lever on a worn spindle where parts are no longer available. I experimented with increasing quantities until it was just strong enough to stay in place. 3-4 drops did the job.

The Loctite site has a lot of useful information on their products.
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Old 09-10-2014, 18:19   #22
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Re: Tapered fittings on thru hull question



Here's what I would do:

Unscrew everything from the seacock, disconnect it from the hoses and throw it away. Then go to a marine store and get an adapter that screws fully into the seacock (the threads match) with hose barbs on the other end to fit your hoses. Also buy a hose "T" to fit the existing hoses. Buy a few inches of the same sized hose.

Screw the adapter into the seacock using pipe dope on the threads. Insert the "T" into the hoses and cut a piece of the new hose to fit between the "T" and the seacock. Put everything together and install quality hose clamps everywhere. Problem solved.
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Old 09-10-2014, 21:59   #23
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Re: Tapered fittings on thru hull question

I gotta go with Delmarry and Ron on this one. What you've got looks like a problem waiting to happen.

At your next haul out I suggest you add a Groco Flanged Adapter and replace the hardware store ball valve with a Groco or Apollo marine valve.

Groco Flanged Adapter IBVF

By using this Flanged Adapter, you eliminate the mismatch of threads between the thru-hull fitting and the ball valve and you protect the thru-hull fitting from side loads.
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Old 09-10-2014, 22:19   #24
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Re: Tapered fittings on thru hull question

This is the image I was looking for.
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Old 10-10-2014, 00:38   #25
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Re: Tapered fittings on thru hull question

Quote:
Originally Posted by HopCar View Post
This is the image I was looking for.
Thanks Parks!

Pictures are worth a thousand words. Now if one could put a street elbow, a tee and a couple barbed fittings it'd be the way to go. Or just rotate the handle and eliminate the elbow.
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Old 10-10-2014, 00:49   #26
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Re: Tapered fittings on thru hull question

This is simpler.

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Old 10-10-2014, 11:06   #27
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Re: Tapered fittings on thru hull question

http://www.highsidechem.com/leaklock.html
This stuff is goop but better than any other pipe joint compound you will find.


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Old 10-10-2014, 11:22   #28
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Re: Tapered fittings on thru hull question

Loctite 242 is just normal ordinary blue loctite, heat not really needed, I always have a tube of blue in the tool kit.
I can't remember the numbers, I go by color, it's the red that takes heat and is worse than 5200 for holding something, good for loose bearing cups and studs that you never want to remove
breakdown of the colors, and anything more than $10 for a small tube and your paying more than you should.
The Difference Between Red, Blue, Green and Purple Threadlockers
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Old 10-10-2014, 12:02   #29
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Re: Tapered fittings on thru hull question

I've been working through plans to replace all of my thruhulls and valves when I haul out next summer but this thread raises a comment and a few questions.

My comment (implied in some posts above) is: Be sure that all of the fittings are marine bronze. If you've ever seen what electro corrosion looks like in fittings you'll have nightmares for months. I'm still having them over a year later.

My questions. Why not have bilge pumps share a thruhull? I can see why you don't want a check valve but I'd think that they could share a thruhull.

I'm also trying to decide whether to use the flange and ball valve approach suggested in Hop-Car's drawing or to use the seacocks. Seacocks are cheaper and a bit simpler but the two part (flange and ball valve) has the advantage of flexibility if there should be a problem with the valve later.

My last question: What happens to the threads when one threads an NPT valve on an NPS thruhull? I've got that situation on all of my thruhulls. It really doesn't matter because I'm going to replace everything and discard the old ones but I'm just curious. Does it crush the threads or just stop turning at the point where things get tight?

Bill
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Old 10-10-2014, 12:10   #30
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Re: Tapered fittings on thru hull question

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...Why not have bilge pumps share a thruhull?...
the two part (flange and ball valve) has the advantage of flexibility if there should be a problem with the valve later...
No, it doesn't.

There are several reasons to not share thru-hulls.

One bilge pump can flow right back into the other, rendering both useless.
And only one pump can be effective--they won't both work when you need them--the output of one will overcome the other.
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