Copper fittings in seawater

[MM5AHO]

Someone mentioned dezincification recently to me, but that got me thinking about copper fittings in seawater service.
Any thoughts about copper pipes in seawater?

 

[bikedaft]

would be interested to see whether we should use it or not

I have a 15mm copper pipe exposed to sea water in the bilge (I use it to drain the exhaust antisyphon box before leave boat - long story), I put it there 3 years ago expecting it to crumble, it seems fine?

 

[JumbleDuck]

would be interested to see whether we should use it or not

I have a 15mm copper pipe exposed to sea water in the bilge (I use it to drain the exhaust antisyphon box before leave boat - long story), I put it there 3 years ago expecting it to crumble, it seems fine?

Copper sheathing isn't particularly thick, and seems to last OK.

 

[Findhorn]

Someone mentioned dezincification recently to me, but that got me thinking about copper fittings in seawater service.
Any thoughts about copper pipes in seawater?

Fortunately copper cant dezincify..

 

[alahol2]

Presumably they used to know what happened as they used to sheath ships with it as a form of antifouling.

 

[Stemar]

My Snapdragon 24's rudder tube was a simple piece of 50 mm or thereabouts copper tube. It died a couple of years after I bought the boat, fortunately on the hard when refitting the rudder. If I'd been in the water when it failed, the boat would probably have sunk. OTOH, that was after nearly 40 years.

The replacement was a lump of windsurfer mast that should be good for the next 100 years or so, so failure won't be my problem.

 

[NormanS]

Many wooden boats were copper fastened, and have lasted for years.

 

[macd]

Early copper sheathing was fairly pure copper, but since the mid 19th Century Muntz metal (60% Cu, 40% Zn, plus a pinch of Fe) has been preferred, being just as effective but cheaper. The Cutty Sark has Muntz metal sheathing.

From Wiki: copper alloys have become important netting materials in the aquaculture industry because of the fact that they are antimicrobial and prevent biofouling, even in extreme conditions and have strong structural and corrosion-resistant properties in marine environments.

Cupro-nickel (up to 90% Cu) is an excellent (if expensive) material for hulls (and ships' condensers, which get a hard life). And, until recently 'silver', coinage.

 

[penfold]

Copper pipe suffers badly if the flow inside is fast; it's a common failure on my company's creaky old ships with seawater flushing lavvys rather than whizbang vac systems.

 

[Neil_Y]

Someone mentioned dezincification recently to me, but that got me thinking about copper fittings in seawater service.
Any thoughts about copper pipes in seawater?

In isolation there is no galvanic action, but if the copper is in any way connected to other metals in sea water it's likely to dissolve, check the EMF series to see where it sits it is certainly more reactive than an SS it may be in contact with.

 

[charles_reed]

Many wooden boats were copper fastened, and have lasted for years.

Unless of vast antiquity I think you'll find they were bronze fastenings.

Copper does gradually corrode in seawater, hence the use for anti-fouling on square-riggers.

Steve may find his windsurfer mast section will be even more short-lived than the copper one - all depends on the galvanic couples present.

It's common brass that de-zincifies and turns into rather porous and weak copper.

 

[NormanS]

Unless of vast antiquity I think you'll find they were bronze fastenings.

Copper does gradually corrode in seawater, hence the use for anti-fouling on square-riggers.

Steve may find his windsurfer mast section will be even more short-lived than the copper one - all depends on the galvanic couples present.

It's common brass that de-zincifies and turns into rather porous and weak copper.

I think you will find that the vast majority of clinker boats were fastened with copper rivets.

 

[VO5]

I think you will find that the vast majority of clinker boats were fastened with copper rivets.

In our club we have the only fleet of Victories outside the UK.
These clinker boats are copper riveted throughout.
Their age range is over 65 years each.
The rivets only need replacing if a plank pops, but the integrity of the rivet itself does not seem to be affected....meaning...they don't corrode or crumble.

 

[MM5AHO]

Reason I asked is that a couple of winters back I changed most of the seacocks. Used DZR ballvalve (though I think the ball is 316 SS??). On two seacocks, which both drain scuppers and cockpit, there is a copper pipe Y junction to allow hoses to be fitted. The copper pipe is in contact with the valve, and that's in contact with a DZR skin fitting through fibreglass.
I replaced one of these Y junctions as one had been a bit crimped by overtightened hose clampsm over the years. Wasn't a serious crimp, but made it worth changing.
These Y junctuions allow 2 hoses of different sizes, to be connected to each valve.
On inspection, there seemed no corrosion or thinning of the copper pipes, though these are only domestic plumbing pipes, brazed with bronze welding rod (gas).
The one that was replaced had done perhaps 20 years, but it could be as much as 40 years, the age of the boat.
This winter I'll be checking the seacocks again, but don't expect to find anything amiss.

 

[macd]

I changed most of the seacocks. Used DZR ballvalve (though I think the ball is 316 SS??).

Almost certainly chromed brass.

 

[macd]

Unless of vast antiquity I think you'll find they were bronze fastenings.

Copper does gradually corrode in seawater, hence the use for anti-fouling on square-riggers.

1. I think not.

2. Why the 'hence' as though there were some logical inevitability about it? Copper is inherently a biocide. Knock a copper nail into the neighbours lelylandii and you'll find out.

 

[vyv_cox]

The coil in almost every calorifier is copper, carrying hot rather than cold seawater in a raw water cooled installation, and therefore far more susceptible to corrosion. I replaced my calorifier at about 20 years old in order to fit one with an immersion heater. I cut the old one up for interest and found the coil to be in virtually perfect condition.

I have also had boats that had copper elbows and pipes in the seawater cooling circuits, none seemed unduly corroded. Whereas at home, blessed with extremely soft water sourced in a mountain lake, we have had several leaks in copper piping that corroded through.

 

[vyv_cox]

Almost certainly chromed brass.

I have come across some that were electroless nickel plated but some could well be chromium. As far as I can ascertain even bronze and DZR valves have brass balls. During the YM campaign we came across several valves that appeared to be perfect externally but the ball had corroded completely away.

 

[nigelmercier]

The inlet and outlet pipes of my sea-water strainer are copper. Had to replace one after 12 years (made from some copper pipe and a sawn-off solder fitting to form a lip).

 

[Stemar]

Unless of vast antiquity I think you'll find they were bronze fastenings.

Copper does gradually corrode in seawater, hence the use for anti-fouling on square-riggers.

Steve may find his windsurfer mast section will be even more short-lived than the copper one - all depends on the galvanic couples present.

It's common brass that de-zincifies and turns into rather porous and weak copper.

You'd be right if it was carbon fibre, but the one I found lying in a corner of our club yard was plain old GRP, so I don't think galvanic couples will be a problem. I'm guessing that what killed the old copper one was a connection to a stainless rudder shaft.