Wet Exhaust stainless.?

Discussion in 'Sailboats' started by howardm, Oct 9, 2013.

  1. howardm
    Joined: May 2010
    Posts: 25
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: Aberdeen, Scotland

    howardm Junior Member

    Hi,
    Can someone advise me as to materials for a water trap.
    I need to fabricate one to fit in a specific place.
    I tried a Vetus plastic one, but it just didn't sit right.

    I found an article which says super duplex would be bullet proof, but, a colleague at work says nickel and sulphur don't go well.
    Would 316 SS be a good choice.?

    thanks
    Howard
     
  2. michael pierzga
    Joined: Dec 2008
    Posts: 4,862
    Likes: 114, Points: 0, Legacy Rep: 1180
    Location: spain

    michael pierzga Senior Member

  3. howardm
    Joined: May 2010
    Posts: 25
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: Aberdeen, Scotland

    howardm Junior Member

    Thanks Michael,
    I have looked at Halyard, still too big.

    It really has to be fabricated to fit my space.
    I have re-engine and gone up to a two-cylinder, hence less space.

    The hoses contain a maximum of 2 litres, so I was going for a 4 litre size box, which needs to be narrow, to fit the remaining space.

    Would the corrosion be rampant ?
    If I made a spare at the same time and did an inspection/swapover annually I think I would be OK.
     
  4. JSL
    Joined: Nov 2012
    Posts: 754
    Likes: 38, Points: 28, Legacy Rep: 41
    Location: Delta BC

    JSL Senior Member

    check out Centek.
    If you make you own from metal try CuproNickel .steel
     
    Last edited: Oct 9, 2013
  5. michael pierzga
    Joined: Dec 2008
    Posts: 4,862
    Likes: 114, Points: 0, Legacy Rep: 1180
    Location: spain

    michael pierzga Senior Member

    The problem with stainless is that it needs oxygen to stay in the passive state. Standing water in the bottom of your exhaust causes trouble.

    If you must use stainless choose a thick gauge of ss for the bottom and sides....places that you know water will stand.

    Carefull welding...no void, pin holes. Ask a specialist.

    Ive had several ss aqaulifts over the years...they all failed over time. Inspect regularly

    You might ask a glass guy how to build one grp. The construction is simple. The complication is that the exhaust system must withstand high temp in the event of a cooling system failure

    High temp resin is used.
     
  6. howardm
    Joined: May 2010
    Posts: 25
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: Aberdeen, Scotland

    howardm Junior Member

    Thanks for the input,
    I am going for 316, maybe I can automatically slow drain the waterlock when left for some time to get oxygen in.

    The Cupro nickel was an idea but apparently is very hazardous to the health.

    I will also have a look at moulding one from glass, that would be quite easy.
     
  7. BMcF
    Joined: Mar 2007
    Posts: 967
    Likes: 45, Points: 28, Legacy Rep: 361
    Location: Maryland

    BMcF Senior Member

    Our welding shop has duplicated quite a few stainless steel sailboat wet exhaust muffler assemblies that had developed pinholes from years of corrosion. We use 316L exclusively and wherever possible, especially the jacketed section of the exhaust pipe where a pinhole assures water drainboard in to the engine exhaust will occur, use thicker material than was used in the originals.

    We did quite a few of them for older Nautor Swan's, for some reason. Not sure if it was the age or that they had originally used an inferior grade of stainless..or both?
     
  8. daiquiri
    Joined: May 2004
    Posts: 5,372
    Likes: 239, Points: 73, Legacy Rep: 3380
    Location: Italy (Garda Lake) and Croatia (Istria)

    daiquiri Engineering and Design

    Hi Howard,
    I see that you have mentioned the 316 in two separate posts, so it is probably not a typo. Since the manufacturing of the wet exhaust will require a lots of welding, I would suggest you to use the 316L (and not 316). SS 316L is the low-carbon variant of the SS 316. Having a low carbon content, the chromium-carbide precipitation in the welded parts of the 316L is significantly reduced and the chrome content is preserved. It gives a better corrosion resistance to the welded areas of the 316L, when compared to 316.
    Cheers
     

  9. MikeJohns
    Joined: Aug 2004
    Posts: 3,176
    Likes: 198, Points: 63, Legacy Rep: 2054
    Location: Australia

    MikeJohns Senior Member

    Slavi
    It's not really an issue with thin wall sections, they cool too quickly to get carbide precipitation. But 316L is marginally better for general corrosion in a wet exhaust but not by much.
     
Loading...
Forum posts represent the experience, opinion, and view of individual users. Boat Design Net does not necessarily endorse nor share the view of each individual post.
When making potentially dangerous or financial decisions, always employ and consult appropriate professionals. Your circumstances or experience may be different.