exhaust material question

[Mr_Boat]

The last section of exhaust is rusting away on my 40 ' trawler . The section is about 15 ' from the engine ( a single 120 lehman diesel ) about 3 ' long . The problem I have run into is the origional exhaust is iron pipe 4.5" o.d. not a common size for exhaust tubing or rubber pieces to make the connection . Locally I have been unable to purchase Iron pipe in a small qauntity . I found some aluminum tubing 4.5" o.d. 1/4 " thick 6061 T6511. My question is how would this hold up to saltwater being pumped through it ? could I just paint the inside of the tubing if corrosion with salt water and aluminum is a concern ? The tubing will be isolated at both ends with a rubber connector.
Thanks

[Tracy Blair]

The last section of exhaust is rusting away on my 40 ' trawler . The section is about 15 ' from the engine ( a single 120 lehman diesel ) about 3 ' long . The problem I have run into is the origional exhaust is iron pipe 4.5" o.d. not a common size for exhaust tubing or rubber pieces to make the connection . Locally I have been unable to purchase Iron pipe in a small qauntity . I found some aluminum tubing 4.5" o.d. 1/4 " thick 6061 T6511. My question is how would this hold up to saltwater being pumped through it ? could I just paint the inside of the tubing if corrosion with salt water and aluminum is a concern ? The tubing will be isolated at both ends with a rubber connector.
Thanks
you should probably stick with any non ferrous metal besides aluminum , send me an email and i will try to locate what you need i live on the gulf coast just need sizes i got 4.5od what length.

[Arrowmarine]

Every boat manufacturing company I have been involved with over the last 18 years has used custom fabricated aluminum exhaust tubes with excellent results. All have been constructed with 6061-T6 seamless tube and either mig, or preferably, tig welded. All aluminum from the engine to the transom. I have never seen a failure or heard of one. The 6000 series alloys have excellent corrosion resistance. Other benifits include no rust, no painting, virtually no maintainance, light weight, easily fabricated into complex curves and shapes. Just take care of them as you would any boat parts exposed to salt water. I personally wont use anything else unless I have to.
I can also ship material to you in small quantities if you are interested.
Hope this helps, Joey