Gate valve replacement question.

[hastingsml]

I am buying a boat that has gate valves that I plan to replace with ball valves. Currently there is a thru hull with the gate valve screwed on. The valve is the type that does not screw all the way down to the inside hull.<br /><br />I have notices two types of ball valves. One has a flange that actually becomes part of the thru hull and tightens down to the inside hull. The other does not have the flange and just tightens down on the threads of the thru hull.<br /><br />Should I just remove the gate valve and screw on a ball valve or remove the inside fitting of the thru hull and attach a ball valve with the flange and seal/tighten it down to the inside hull?

 

[tommays]

Re: Gate valve replacement question.

<br /><br /><br />One problem is that a lot of through hull fittings like this

<br /><br />are NPS and not tapered so a standard ball valve will really not tighten on it correctly<br /><br /><br />tommays

 

[SS MAYFLOAT]

Re: Gate valve replacement question.

Here is a pic of how mine is. I used teflon tape on the threads for the ballvalve. Didn't have any leaks or problems except for my tansom being rotted. That is why it is not in the boat. If you remove the thruhull fitting, use 3M's 5200. Some good stuff right there.<br /><br />

<br /><br />Tommays is right about the threads. The ballvalve will be tapered while the thruhull fitting is not.

 

[Buttanic]

Re: Gate valve replacement question.

I never had a problem with a regular ball or gate valve on a through hull. They tighten up OK and considering the pressure on a through hull at 24" deep is only about 1 psi with some pipe dope on the threads it's not about to leak or come off. Matter of fact a 31 Bertram I had came from the builder with regular valves on through hulls. Bertram is not knon to pinch pennies so they must have felt it is not an issue.