Can you dismantle a gate valve?

[Kelpie]

I want to remove a through-hull and valve in the engine compartment, but if I try to unscrew it the handle of the gate valve hits an obstruction. Can I reduce the size of the valve by removing part of it? This would allow me to unscrew it much mroe easily.

 

[sailorman]

I want to remove a through-hull and valve in the engine compartment, but if I try to unscrew it the handle of the gate valve hits an obstruction. Can I reduce the size of the valve by removing part of it? This would allow me to unscrew it much mroe easily.

yes close it first then a spanner on the hex section below the spindle. it could be very tight & immovable

 

[Norman_E]

I want to remove a through-hull and valve in the engine compartment, but if I try to unscrew it the handle of the gate valve hits an obstruction. Can I reduce the size of the valve by removing part of it? This would allow me to unscrew it much mroe easily.

If you cannot get it apart, just saw the handle off, unscrew it and fit a ball valve in its place. I assume that you are on the hard to do this. In my opinion gate valves are a bad idea on boats. Most are made of common brass, and when worn they often fail to close completely. I have also had a domestic one that stripped its internal thread on closure and could not be opened.

EDIT: The other issue with gate valves is that they take several turns of an often stiff handle to cut off the water flow. Not much fun on a boat if water is pouring in from a ruptured hose. The ball valves turn off with a 90 degree turn and give obvious visual open or shut indication, whilst with gate valves you just cannot see whether they are open, shut or half way.

 

[Kelpie]

Thanks guys, I hoped it would come apart like that.
And yes a ball valve will be replacing it! DZR whilst I'm at it.

 

[ghostlymoron]

Pat Manly, in his book Simple Boat Maintenance, states 'gate valves have no place on a boat'.................and then devotes a page and a half to describing the maintenance. This shows you how to dismantle them. But having removed it, I would bin it (and any others you may have) and replace with quarter turn ball valves - DZR grade of course.

 

[aquaplane]

When I was changing my cockpit drain valves I was alarmed to find that the bonnet came off in my hand with far too little effort.
The shaft wasn't broken as in this picture, but the thread on the bonet only had one turn on it.

 

[rob2]

If you cannot get it apart, just saw the handle off, unscrew it and fit a ball valve in its place. I assume that you are on the hard to do this. In my opinion gate valves are a bad idea on boats. Most are made of common brass, and when worn they often fail to close completely. I have also had a domestic one that stripped its internal thread on closure and could not be opened.

A properly made bronze gate valve, given proper maintenance will outlive most of us and give good service. Many ball valves are also made of unsuitable materials and there isn't always room for the 90 deg swing of the handle. When looking around chandlers, most valves do not state what material they are made of and the main suppliers mail order catalogues offer brass first for underwater use.

Just saying, ball valves can also be rubbish if made of the wrong materials (and the handle usually is) and it requires great care to get really good valves of any design. I have had a ball valve spindle fail (mild steel!) so the handle wasn't indicating anything. O course the other option is to knowingly use domestic brass fittings and throw them away every year!

Rob.

 

[samwise]

Pat Manly, in his book Simple Boat Maintenance, states 'gate valves have no place on a boat'.................and then devotes a page and a half to describing the maintenance. This shows you how to dismantle them. But having removed it, I would bin it (and any others you may have) and replace with quarter turn ball valves - DZR grade of course.

Nigel Calder says the same thing. but his statement that they have no place on a boat is unqualified. We had a couple on our Sadler 29, I think simply because there was no room to swing a handle. I always viewed them with suspicion. Our current boat has Blakes throughout.

 

[prv]

The cockpit drains on KS were both gate valves when we bought her. Both had failed, but the surveyor only cited one - the other had failed in a way that was impossible to detect from the outside.

Pete

 

[Kelpie]

OK, the valve is off, intact. It says on it:
Pegler England
3/4
PN20

On the handle:
9/180oC
BS5154B

It's very green but doesn't seem to be losing any material.
Would save me a bit of time if I can just stick it back on!
Any suggestions?

 

[ghostlymoron]

OK, the valve is off, intact. It says on it:
Pegler England
3/4
PN20

On the handle:
9/180oC
BS5154B

It's very green but doesn't seem to be losing any material.
Would save me a bit of time if I can just stick it back on!
Any suggestions?

BS5154 refers to brass gate valves. Your valve may be DZR but I wouldn't bet on it. My advice would be to replace with a quality ball valve - and all the others.

 

[James_Calvert]

OK, the valve is off, intact. It says on it:
Pegler England
3/4
PN20

On the handle:
9/180oC
BS5154B

It's very green but doesn't seem to be losing any material.
Would save me a bit of time if I can just stick it back on!
Any suggestions?

I would clean and grease the internal working parts, checking for any deterioration. Check the water gland as well, the spindle should turn fairly easily. You might need to take this apart a bit and get some grease in there as well. Reassemble. It should go back together easily, only needing a spanner for final tightening. (If it doesn't, something is misplaced which will be damaged if you force it.) If you've loosened the gland nut, check for leaks on relaunch and tighten up just enough to stop the leak but not too much. The valve should work easily using little effort. Repeat annually.

That's what works for the two gate valves in my Sadler 32.

 

[Giblets]

Words of wisdom from a plumber who has dismantled many gate valves in his time.

In order to remove the "guts" of a gate valve it is vital that you support the body of the valve with a pair of Stilsons or similar before trying to use an adjustable spanner on the flats below the shaft. If you don't you could end up either loosening the skin fitting or, at worst, ripping said fitting clean out of the hull!

 

[l'escargot]

I have just removed 2 x 43 year old gate valves from my cockpit drains. One, which was easily accessible and regularly operated, was perfectly serviceable and I considered reusing it. The other, which was less accessible and operated less often, appeared ok but I was able to bend and break the shaft by hand.

They have both been replaced with 2 new ball valves and while I was at it I replaced the 2 skin fittings, although unnecessarily as they were both found to be in good condition after I had taken the angle grinder to them.

Somehow though I doubt whether the replacements will all last another 43 years...

 

[ghostlymoron]

I would clean and grease the internal working parts, checking for any deterioration. Check the water gland as well, the spindle should turn fairly easily. You might need to take this apart a bit and get some grease in there as well. Reassemble. It should go back together easily, only needing a spanner for final tightening. (If it doesn't, something is misplaced which will be damaged if you force it.) If you've loosened the gland nut, check for leaks on relaunch and tighten up just enough to stop the leak but not too much. The valve should work easily using little effort. Repeat annually.

That's what works for the two gate valves in my Sadler 32.

What do you use if you need to re-pack the gland?

 

[James_Calvert]

Good question, but this hasn't happened yet. The packing material in my gate valves is in the form of a black compressible rubbery cylinder, and these were still serviceable when I last totally dismantled this part of the valves. I've subsequently used self amalgamating tape on top of this on one of them, which works fine. That should work for a total repacking if necessary, but a bit of rubber tubing of the right internal diameter and wall thickness would be less fiddly to introduce if it could be found. Whether such materials would last another twenty years before repacking again is another matter...

 

[poter]

get good valves

Ok a word from another old plumber....

If you have a Pegler valve, its almost certainly brass, which is a no no.

Get yourself a blakes or even a plastic ball valve IMO you will not have a risk of them failing.
Have a look here for PVC valves: http://www.johnsonvalves.co.uk/Plastic_Valves.htm

Or try your local Plumb center.

Good luck

 

[vyv_cox]

The biggest problem I have found with gate valves occurs where the spindle connects with the gate. This point has a small cross section and on a brass valve it fails by dezincification. The gate closes because the spindle is pressing it home but when trying to open it nothing remains to pull. It can be difficult to detect this, which on cockpit drains could cause flooding of the boat by rain water.