Fuel Tank Pick up, OK to use copper?

[thinksun]

Hi all, first post- but been watching for long time.

I'm installing a new to me fuel tank in a cool 71 Sidewinder Lo-Pro restoration project. The original pick up line was 1/4" steel and I need at least 3/8" for the 6 cyl merc. I found an adapter for the pipe thread fitting on tank top that solders to 1/2" copper. It looks good to me but I am wondering if I will have problems down the road using copper. I attached two pictures. All comments appreciated.

 

[MikDee]

Re: Fuel Tank Pick up, OK to use copper?

I would be concerned about electrolysis, from dissimilar metals, an electric charge that might be dangerous, and, or, cause massive quick erosion of all surrounding parts, but I'm just not sure if this is the case, or not?

 

[thinksun]

Re: Fuel Tank Pick up, OK to use copper?

Good point. I have now found the related topics which reference copper pipe/tubing and feel that it would be ok. I am not sure about the soldering material reaction or corrosion.

 

[studlymandingo]

Re: Fuel Tank Pick up, OK to use copper?

Can you use steel or aluminum tubing, and brass compression fittings?

Wouldn't have to worry about electrolysis.​

 

[MikDee]

Re: Fuel Tank Pick up, OK to use copper?

Being a retired pipe fitter, I know they make 1/2" brass pipe threaded both ends in various lengths, called a brass "nipple", you would probably be ok with that instead.

 

[thinksun]

Re: Fuel Tank Pick up, OK to use copper?

I'll look for the pipe nipple or other piping, thanks.

 

[Texasmark]

Re: Fuel Tank Pick up, OK to use copper?

I think steel would cause you more corrosion grief than copper ever would. Copper seems to have the remarkable quality of oxidizing the outer layer and it remain intact, protecting the metal and preventing further corrosion; unlike steel which does the same thing but it flakes off and keeps corroding.

Copper is one of the best electrical conductors, much better than steel, so electrical problems when using copper are not a problem.

The concern with copper would be from a vibration point where the copper could work harden and rupture. I would say that in a boat the biggest stress would be at the connections. So if you have a long unsupported run and at one end is a connection and obviously if the long run were allowed to bounce up and down you might have a problem. So clamp it so that it can't flop around. It doesn't have to be totally rigid.

My Materials Application chart shows copper (and alloys) to be in the same element group (Group IV), no reaction when touching each other, with Nickel, Chrome, SS, Gold, and Silver.

So, for the least corrosion or potential, at the interface, looks like brass (copper alloy) fittings are your best bet.

Tin and lead, which make up solder, are in the adjacent Group III and it is said that adjacent groups can be used together with minimal corrosion. But, in a marine environment I think I would stay with brass.

So it looks to me like the the answer is unanimous.

Mark

 

[studlymandingo]

Re: Fuel Tank Pick up, OK to use copper?

Well ixna on the eelsta, but you can get aluminum tubing as I stated before, it will work with brass fittings. I would personally use compression fittings.

You can also buy a poly pickup tube kit that comes with an aluminum fitting. I purchased one when I recently retrofitted a new fuel tank in my boat.​

 

[BillP]

Re: Fuel Tank Pick up, OK to use copper?

Copper is an excellent choice for fuel line and it will last longer than most others. You just have to do a careful installation with compression fittings to keep them from leaking...always use new ferrules. Before copper got so expensive it was used on motors and boat fuel systems of all sizes without problems. Brass is good for bells and home compressor fittings.

b.

 

[Scaaty]

Re: Fuel Tank Pick up, OK to use copper?

Yep, 3/8 copper line on my 350 GM. But I used plain old brass compression fittings. Big selections at any Home Depot. I don't like the solder idea simply because it will be a much stiffer joint, prone to fatigue/cracking. OK on house water pipe, but bounching and vibration in a boat a different story. Compression fittings work fine for me.

 

[Texasmark]

Re: Fuel Tank Pick up, OK to use copper?

Studly, my Mat Appl chart shows Alum and it's alloys in Group II. Copper is in Group IV. Mil-Std-454 is the origin of the chart and they do not recommend a Group II material mated to a Group IV material because of corrosion problems.

Course plating is something else. I think the interface has to be exposed to the atmosphere to have the corrosion problem.....needs oxygen.

I know we used to plate dissimalar materials with a suitable material so that we could attach them to a material in another group. Also, tin-lead solder is in Group II and it solders copper tubing in most new houses in the USA....but that is a plating process also so I guess that's why it works.

Mark

 

[PHILRAJOTTE]

Re: Fuel Tank Pick up, OK to use copper?

Tempo Makes An Aluminum Pick-uo Tube You Just Cut To Size And Thread In To 3/8 Npt Bung On Tank

 

[rschnack]

Re: Fuel Tank Pick up, OK to use copper?

If I remember correctly from my building days, the copper you solder as in the picture is "rigid copper". There is also "flexible copper", which is what is typically used for things like hooking up the ice maker in the fridge. The flexible copper is used to allow for movement. It can also be flared. Compression fittings seem to seal better on the flexible copper. I believe that is what was used on the old outboards. I don't know if it is a different alloy. I think the rigid is stress hardened. It seems like it would be scary to make a solder repair to a damaged gas line.
RCS