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Old 08-06-2015, 17:58   #1
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Copper pipe for raw water?

HI, I've done a fair bit of searching on this but I can't find anything definitive Is it ok to use copper pipe on the raw water circuit of my engine cooling?

I have a Perkins 4108 which I'm switching from the old heat exchanger system to the newer Bowman h/x setup and so I'm having to devise my own piping

What's best practice? Copper is easy to bend
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Old 08-06-2015, 18:07   #2
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Re: Copper pipe for raw water?

All the cooling plumbing on Volvo Penta engines is copper. (and expensive )
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Old 08-06-2015, 18:35   #3
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Re: Copper pipe for raw water?

The only issue with copper is you'll want a bit of hose somewhere between the raw water inlet and pump to avoid excessive vibration in the copper, which would work harden over some little time.
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Old 08-06-2015, 19:41   #4
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Re: Copper pipe for raw water?

Thanks all!
So there is no problem with electrolysis, I guess as along as the copper is separated by rubber hose from the other metals?
Is there a better thickness or is normal plumbing pipe ok?
Thanks
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Old 08-06-2015, 19:56   #5
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Re: Copper pipe for raw water?

Keep your eye out for velocity erosion when using copper pipe, particularly around bends where the metal may be stretched thin, or in areas where flow turbulence might occur.

DougR
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Old 08-06-2015, 20:18   #6
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Re: Copper pipe for raw water?

Google "velocity erosion in copper pipe" for further info regarding recommended maximum velocities in cold and hot water copper pipe systems.

Reminds me of working in Diego Garcia many years ago where we encountered pitting in copper pipes in the sea water circuit of Volvo Penta engines due to high water velocity and high ambient water temps.....a problem not seen elsewhere in the world. Changing to a harder alloy resolved the problem.

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Old 08-06-2015, 20:35   #7
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Re: Copper pipe for raw water?

Hmm, so I probably should replace the existing bits of copper pipe of unknown age...
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Old 09-06-2015, 05:44   #8
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Re: Copper pipe for raw water?

It isn't necessary to scrap pipe just because it is old. In fact, if it's old it's probably OK because it hasn't failed over the years. Examine the inside of the pipe for erosion in areas of restriction or bends. If the pipe has problems you can see the areas where there has been erosion and turbulence.

As mentioned above, do some online searching.....you will find design guidance and photos of what velocity erosion looks like inside a pipe.

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Old 09-06-2015, 09:33   #9
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Re: Copper pipe for raw water?

BY choice I would use bronze or monel.
If you are using copper I would at least use USA schedule 40.
McMaster.com has the good pipes and fittings.
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Old 09-06-2015, 09:34   #10
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Re: Copper pipe for raw water?

Go ahead with the copper, erosion if not normally a problem unless it is downstream of a area of turbulance (nice elbows, straight through valves).

Always best to throttle the flow thru a heat exchanger at the outlet of a cooler.

I'm old enough to remember copper pipes in ships Engine Rooms, copper is better because it wont get marine growth on it. Ships now use protected steel and central FW cooling systems.
As sailor chic says, use flex pipe for transition, will stop galvanic action, will be long lasting.
Best practice? don't know but polished copper will look a treat.
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Old 09-06-2015, 09:35   #11
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Re: Copper pipe for raw water?

I don't know about for the engine but I'm thinking about using PEX for inside water. I've used all through the cottage and it's been great. Has to be better than cu on vibration and it sure is easy to install where there are curves.
Bill
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Old 09-06-2015, 15:50   #12
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Re: Copper pipe for raw water?

In Aus, we have various grades of copper.
Type A is thick, heavy wall and really robust.
Type B is the normal plumbing pipe
Type C is the soft copper rolls for refrigeration.
Try for A at a plumbing supplies rather than hardware stores, but at 6m lengths, take a big wallet.
Type B is OK for most work, but if you are in polluted waters, ordinary copper will get eaten away by corrosion in time, 70/30 copper nickel and other more exotic types work well, but are frighteningly expensive and a tad tricky to work.
Roger
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Old 09-06-2015, 18:07   #13
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Re: Copper pipe for raw water?

In the past, ships were sheaved in copper to resist marine growth so copper should be fine for engine plumbing, with the cautions others have pointed out. I would rather, and I DO use marine grade plastic fittings and the correct grades of flexible piping. My local supplier is General Marine NZ LTD. However there is such a vast array of fittings that it is possibly better to personally select them rather than buying online unseen. You need to be aware of either inside or outside measurements. If you don't have a local supplier, then making your own out of copper would be a suitable alternative. I doubt if it would be cheaper than using marine plumbing suppliers and certainly more work. Normal inspections over the years should detect potential problems soon enough. If attaching flexible hose to plain copper pipe I would go with plenty of overlap and double hose clips. There may (or may not) be a problem with compatible diameters. Liquid soap is always good to help fit flexible pipe on any fittings. Plastic fittings normally have serrated tails to better grip attached flexible pipes. This is not the case with plain copper although compression fittings work but then you may as well use correct grades of plastic.
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Old 09-06-2015, 18:17   #14
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Re: Copper pipe for raw water?

Hi all, thanks for your help, this is doing my head in slightly. Easy conversion me thought haha

For the Bowman heat exchanger end caps I've worked out I need
22mm (7/8th) and 28mm (1 1/8th) tubing. These aren't standard plumbing sizes and I need to be able to put some 90 bends into it.

Piece by piece I'll get there

I think I need to buy a pipe bender...
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Old 09-06-2015, 18:23   #15
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Re: Copper pipe for raw water?

In my earlier note I should have added the issue of fittings. This is the biggest problem with self fabricated arrangements and I have had many a hose part company with the pipe under pressure, even with twin clips, but then they were generally used on a glycol circuit not plain raw seawater.
Adding serrated tails seems simple, but the jointing method must be considered. Lead solder? Silver solder? Most compression fittings for copper pipe are brass, so watch-out there, but the solders are also a complex alloy. If you get plain lead solder, that is great but watch the flux as the acid can also attack things.
Not really as complex as it sounds, you just need to be aware of the issues and take care.
Roger
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