Question About Copper Exhaust System.

[frozenhawaiian]

exhaust question for you guys. my boat has jacketed copper exhaust system there is one 6 inch or so section that is not jacketed, this system is new and was never fully installed under the previous owner, the mechanic I was working with to finish the install doesn't want to install it due to concerns over melting of either the copper or of the brazing, of this one section of non jacketed copper exhaust. the joints appear to be brazed with copper or brass and not your standard tin solder. what are you guys thoughts on the issue? oh also there's a 10in section of stainless flex pipe before the copper section even meets the engine. below is a photo of the section in question.

Untitled by Nathan Pablo, on Flickr

[topmast]

Looks kinda clumsy. If in SS probably avoid the problem of heating. Brazing the copper (or everdure) was a step in the better than solder which wouldn't work at all. The water nipple has to be a barbed unit if you expect a hose to stay on it. The 10 inch SS flex pipe is going to get pretty hot. Insulation? Where's the muffler in all this or is a straight shoot out the back? Copper can work harden with vibration . Personally ,I like catching both water and ex down into a SS can(build in a drain) and then it's straight up onto a rubber hose and out

[model 10]

Probably done with silver solder. It needs to be hot to melt ,much hotter than your exhaust by the time it gets to that section. Lot of heat coming from that set up, I'm kinda with your mechanic there.
Something I saw that worked for that kind of thing was a heavy wrap of asbestos type material then coated with a heavy layer of Silicone to keep it clean and sealed. Pretty ugly/artsy looking with the silicone by spread hand but it works.

[frozenhawaiian]

Originally Posted by topmast

Looks kinda clumsy. If in SS probably avoid the problem of heating. Brazing the copper (or everdure) was a step in the better than solder which wouldn't work at all. The water nipple has to be a barbed unit if you expect a hose to stay on it. The 10 inch SS flex pipe is going to get pretty hot. Insulation? Where's the muffler in all this or is a straight shoot out the back? Copper can work harden with vibration . Personally ,I like catching both water and ex down into a SS can(build in a drain) and then it's straight up onto a rubber hose and out

no muffler, just a straight shot up and out to the transom

[tkeithlu]

I think I'm seeing brazing, not soldering; if so the temperature of the part per se isn't a problem. Heat from it may be - copper is one hell of a conductor. But, hot exhausts are nothing new. Amazon sells bunches of fiberglass exhaust tape, largely for motorcycle exhausts. So does NAPA. I wrapped all my pipe from the exhaust manifold to the muffler becaue it's where I could bump into it and burn the living !@#$ out of myself. That has been very successful. I tied mine with aircraft safety wire, but the kits available come with wire ties that are made out of SS wire.

[topmast]

Wrap hot parts with fiber glass cloth,blanket, tape. Used to use asbestos, but that was then.Fire place stores have some neat stuff.Glass rope packing. Tie with SS wire or better yet paint with water glass >(aluminium silicate full strength) Must cut it off like a cast so know it's what you want.

[topmast]

A straight out the back type can hold or catch enough water (think following sea under sail or drifting down wind) Number one killer of engines on poorly thought out designs

[HappyMdRSailor]

Originally Posted by topmast

A straight out the back type can hold or catch enough water (think following sea under sail or drifting down wind) Number one killer of engines on poorly thought out designs

+1
Definitely a concern...

[model 10]

Originally Posted by topmast

A Number one killer of engines on poorly thought out designs

But it's a Hinkley!
Another design that sucks is a wet exhaust where water is pumped around the exhaust pipe which is inside a hose. The pipe rots out and water leaks into the exhaust.
Once you figure out how a water lift system works, it's not hard to put together. Lots of mufflers and elbows etc for sale to make it work.

[Jim Cate]

fwiw:

Years ago I owned a Yankee-30 which had an Atomic 4 engine, and the factory exhaust system at the engine end was made up of common copper plumbing fittings. They were brazed together as needed, with an unknown brazing alloy. After some eight years or so, pin holes developed in all the brazed joints and the system leaked, increasingly badly. I purchased a similar bunch of fittings at the local hardware store, and instead of brazing, I (having access to the equipment) TIG welded it all together. It worked a treat, never again leaked in the remaining years I owned the boat. There were no heat issues, or other problems attributable to the copper materials. It is possible that there are some subtle differences in the exhaust gasses of petrol vs diesel engines... dunno about their effects on the copper.

Jim

[um saudade]

Jim Cate pretty much nailed the big issue with copper and that being the quality of the brazing alloy. And on his replacement he did the best possible fabrication technique, which is to TIG weld the joints.

Copper will last for years in exhaust systems if heavy walled pipe is used. We can’t tell from looking at the picture what the wall thickness is. It is type “M” it won’t have a very long service life.

I would be more suspect of what the poster is calling flexible stainless. There is a lot of flexible exhaust out there that is not gas tight, a bad situation for an enclosed space such as a boat.

I would encourage a little research with the possibility to going to a standard mixing elbow and a water lift muffler.

[model 10]

[QUOTE=Jim Cate;2172982]fwiw: TIG welded it all together.


Another post on the forum had me give TIG welding on copper a try. I'm no ace by any measure but I found it very easy to weld

[topmast]

Brazing up any salt water /exhaust is doomed as the zinc dissolves and leaves it porus. Before Tig I got prettyy good with Oxy acetylene ,using strips cut from scrap bronze water tanks. Many uses on a boat for stuff made from those old tanks.

[chris95040]

Originally Posted by um saudade

I would be more suspect of what the poster is calling flexible stainless. There is a lot of flexible exhaust out there that is not gas tight, a bad situation for an enclosed space such as a boat.

I thought one of those flexible, braided stainless fittings was the answer to my prayers a few years ago until I saw how leaky it was. I guess you dont have to be quite as careful with automotive stuff thats out in the open.


carbon monoxide is a real threat here.

[topmast]

Unless its a real SS flex fitting (available) better to use black iron plumbing fitting . Taking that back ,better to use black steel NPT plumbing fittings.