Seacock broke in my hand!

I think the ball material is irrelevant for three reasons. First, it's chrome plated so the brass won't see seawater for years. Second it is mostly under no load so even if dezinced it won't break. Third, even if the ball disappears in a puff of smoke the boat won't sink

The body of the valve is the very opposite, on all three counts. So I buy the bronze bodied valves. All imho! It's annoying that we have to be bothered by all this.
 
This question must have been asked numerous times on here before, in which case I've missed the answer, but with all the composites available today, why are seacocks still made of materials that seem so unreliable in the environment they are used in?
 
scubaman said:
This question must have been asked numerous times on here before, in which case I've missed the answer, but with all the composites available today, why are seacocks still made of materials that seem so unreliable in the environment they are used in?
Click to expand...

The gate valve has many uses and a seacock is not one of them, it's up to the person installing it to select the correct part.
 
scubaman said:
Using those seems like a no-brainer but there must be some obvious reason not to.
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I think the market is just nervous of plastic (irrationally perhaps), but also we lack tech info on these items including mechanical strength data at different temperatures. The other problem is that they lack the "lego" nature of bronze items, where you can attach any hose diameter to any size valve and any size hole in the hull, and you can have scoops or plain entries, you can add a weed filter, you can make the valve stand up from the hull if that gives you easier access, you can add a second valve (electric), and so on. This Lego-ness is quite important
 
jfm said:
I think the market is just nervous of plastic (irrationally perhaps), but also we lack tech info on these items including mechanical strength data at different temperatures. The other problem is that they lack the "lego" nature of bronze items, where you can attach any hose diameter to any size valve and any size hole in the hull, and you can have scoops or plain entries, you can add a weed filter, you can make the valve stand up from the hull if that gives you easier access, you can add a second valve (electric), and so on. This Lego-ness is quite important
Click to expand...

Found some interesting products from these guys -> http://www.trudesignplastics.com/marine/products

They seem to have a wide range of products for marine use and a pile of certifications to convince customers (although I have no idea what those certs actually test for and subsequently prove). I noticed that some products mentioned an operating range of -20 to +80 C which may or may not be enough for every purpose, eg. engine room.

As such, composites have been used on very demanding applications for years so they would seem an obvious way to go in the marine industry as well.
 
scubaman said:
Found some interesting products from these guys -> http://www.trudesignplastics.com/marine/products

They seem to have a wide range of products for marine use and a pile of certifications to convince customers (although I have no idea what those certs actually test for and subsequently prove). I noticed that some products mentioned an operating range of -20 to +80 C which may or may not be enough for every purpose, eg. engine room.

As such, composites have been used on very demanding applications for years so they would seem an obvious way to go in the marine industry as well.
Click to expand...
Thanks. That looks good and has "lego" -ness. I can see the case for using them but (a) they're no use in e/room if their rated Tmax is 80deg, (b) I suppose I still worry about mechanical strength compared with bronze, if something heavy is stored in the bilge and hits them, (c) bronze is mechanically much stronger and very corrosion resistant, so why switch from bronze?
 
aquapower said:
The gate valve has many uses and a seacock is not one of them, it's up to the person installing it to select the correct part.
Click to expand...

It's interesting that this is stated so frequently. All of the seacocks on Dragoon were gate valves - this is a Swedish boat built 36 years ago. I have only changed them (2 or 3) when the mechanism itself has failed/seized. The must be bronze as they haven't dezincified. There are still several on the boat. I fear for changing them in case I end up fitting an inferior part to what was there....especially after the recent problem.

I understand the challenge though of a mix up of brass gate vales and bronze gate valves. I strongly suspect that's what happened to me here. Either in the chadlery, or in manufacture.....or parts are being supplied on the cheap and are not what the supplier claims they are.

I think I'm one of the persons who now also asks - how do I know what I'm buying / fitting?
 
jfm said:
Thanks Dragoon for the update and good to hear it all came good in the end.
Yep, gate valves are best avoided. They aren't used widely in this type of application so there is temptation for manufacturers not to use all bronze. Ball valves are a much safer bet, sourced from Asap or Aquafax (though, if I recall correctly, Aquafax were guilty of mislabelling brass/bronze in that PBO test several years ago). I buy the seaflow branded bronze ones from Asap, fwiw

Nick-H's story/picture above is quite worrying and makes you think!
Click to expand...

Thanks JFM.
Incidentally, on ball valves, I've had them fail. I fitted a 1.5" or 2" (forget which) one for the outlet of the forward head, and a year later it had seized - (possible marine growth internally?) An attempt to free it bent the shaft and I had to replace it again (it was a real pig to fit as well due to close proximity to the head - I had to remove the toilet and replace the hose also.

I get the impression there is no panacea with these things. Even Blakes valves can seize, although I've always managed to free them off.
 
dragoon said:
It's interesting that this is stated so frequently. All of the seacocks on Dragoon were gate valves - this is a Swedish boat built 36 years ago. I have only changed them (2 or 3) when the mechanism itself has failed/seized. The must be bronze as they haven't dezincified. There are still several on the boat. I fear for changing them in case I end up fitting an inferior part to what was there....especially after the recent problem.

I understand the challenge though of a mix up of brass gate vales and bronze gate valves. I strongly suspect that's what happened to me here. Either in the chadlery, or in manufacture.....or parts are being supplied on the cheap and are not what the supplier claims they are.

I think I'm one of the persons who now also asks - how do I know what I'm buying / fitting?
Click to expand...
l

The use of gate valves on new boats has not been allowed since the RCD was introduced, one of reasons given is that you can look at ball valve and see if it's open or closed, going back prior to this I seem to remember most boat builders have fitted gate valves, things move on.
 
jfm said:
Thanks. That looks good and has "lego" -ness. I can see the case for using them but (a) they're no use in e/room if their rated Tmax is 80deg, (b) I suppose I still worry about mechanical strength compared with bronze, if something heavy is stored in the bilge and hits them, (c) bronze is mechanically much stronger and very corrosion resistant, so why switch from bronze?
Click to expand...

J,

sorry for reviving an old thread (that I missed back then...)
I also fitted Trudesign all around MiToS (must be 8 below w/l from 1/2 inch to 1 1/2) lego-ness is definitely there and working fine.
Had a problem when installing with one skin fitting (3/4 iirc) slipping (me benig stupid and trying to tighten it while Sika 291i (or 292 don't remember the one, but anyway was the right one for the job) was still soft and I had noone outside to keep the skinfiting from twisting, so it twisted :(

That meant that I had to remove it. When the time came to do so (a couple of months later and just a few days before launching) I had a very hard time doing so. Thought I'd break it with a hammer (1kg job), flexed but didn't feel a thing, then thought I'd bend and break it levering with a long and strong pry bar, nothing, then used a sharp chisel and said hammer and took me a good 10mins to eventually cut it.
I'm very confident that unless the whole 500kg of the bloody engine drops on a Trudesign fitting, it wont break!

Now regarding temps I wonder what temp are the pipes with the ss wire wound on them are rated. I'd definitely expect the hose to fail first.

Concluding I'd question your a and b above and the only reason for going plastic fantastic was that I wasn't at all sure of what I was buying locally as even the translation of brass and bronze in Greek is rather confusing...

Is dezincification linked to electrolysis somehow?

cheers

V.
 
I would guess it may be a old common problem. Everyone is very very careful about hull fittings and valves. Then when you just need a hosetail reducer, and the local plumbing merchant or ebay has a brass hosetail. Not suggesting, just guessing, but seen it before. Apologies if wrong
 
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