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Old 08-25-2014, 03:18 AM   #1
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flexible wet exhaust pipe

Hi All,

The stainless exhaust pipe from the riser to the muffler has developed some rust and pinholes have started to occur. I'm considering switching to a flexible hose product rather than having new stainless pipe fabricated.

Can anyone offer any advice on doing this? Seems all the flexible pipe available is only rated to +100C and I assume temps would be higher than this as the pipe is situated just aft of the turbo. The motor is a Volvo TAMD41A.

Just started my search today so any and all advice/warnings etc are welcome.

Thanks.
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Old 08-25-2014, 07:28 AM   #2
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Measure the temp with a heat gun under 10 min of full load.
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Old 08-25-2014, 08:16 AM   #3
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It sounds as if you are considering the use of rubber wet exhaust hose in the very hot dry exhaust flow directly downstream of the turbo. I think that would be a really bad idea. Flexible metal exhaust hose might work for a while. Can you post a picture?
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Old 08-25-2014, 08:33 AM   #4
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Look at the blue hose.

Trident Marine: Wet Exhaust Hose

But you need to stick with SS coming of the turbo or manifold. As mentioned need pictures.
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Old 08-25-2014, 10:16 AM   #5
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Let's step back and make sure we are all talking about the same thing.

In a typical installation the exhaust from the turbo goes up in a fabricated stainless steel "riser" and then bends down to an "injection elbow" or "mixer" where sea water is introduced into the exhaust stream to cool it. After that Trident or similar exhaust hose is used to go to the muffler.

So if you are talking about the "riser" then it has to be fabricated from stainless steel pipe- usually schedule 10 with a double wall mixer with holes for the raw water to be injected into the gas stream.

If you are talking about after the mixer then rubber hose can be used as the exhaust gas is cooled in the mixer sufficiently for rubber. If you are concerned about temps then use blue silicone hose as it is good for several hundred degrees F.

But rubber hose can't be bent significantly. There is one common and maybe another uncommon solution if you need to bend more.

The common solution is to use fiberglass elbows such as made by Centek, either 45 or 90 degrees to go where you need to go and rubber hose before and after the elbow.

The uncommon solution is to use a braided flexible stainless steel hose. I have never seen it in the large diameters needed for a trawler exhaust system as I suspect it isn't any more flexible than rubber at those sizes.

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Old 08-25-2014, 10:39 AM   #6
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Thanks for the input all. Ok - here's a diagram of the system:



As you can see - the riser (or elbow) -Part #20 - sits right on the turbo. That is where the water is injected. My rusted exhaust pipe is part #24. Well, not exactly as it's been custom-made by PO. It goes to the muffler, then out the back.

Attached (crappy - sorry) pics show where I'd cut the existing pipe (yellow lines) - then use the flexible pipe (clamped onto the two ends). So yes - it would be in the wet part of the system.

Reason I'm considering NOT just having a new SS pipe fabricated is that the fabricator I spoke to estimed 4-5hrs work ($75/hr) + materials. I doubt I'd get out of it for under $500.
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Old 08-25-2014, 10:44 AM   #7
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That should not be a problem
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Old 08-25-2014, 11:13 AM   #8
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I agree it should not be a problem. You could also change the stainless bends for fiberglass elbows and have no more pin holes in the future.
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Old 08-25-2014, 11:22 AM   #9
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If it worked there would be examples, I have never seen or heard of it.
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Old 08-25-2014, 11:28 AM   #10
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Quote:
Originally Posted by rochepoint View Post
I agree it should not be a problem. You could also change the stainless bends for fiberglass elbows and have no more pin holes in the future.
That is what I would do. Replace part 24 with Trident exhaust hose and a couple of Centek 45 deg elbows. You could use a "hump hose" at one or both of the joints. These allow for a bit of misalignment.

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Old 08-25-2014, 12:53 PM   #11
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If it worked there would be examples, I have never seen or heard of it.
If you're talking about using hose and fiberglass elbows instead of the SS pipe, it works and it's very common. In fact you're more likely to that than SS pipe.
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Old 08-25-2014, 01:37 PM   #12
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You might consider using Trident Blue Corra-Sil Marine Wet Exhaust & Water Hose (SAE J2006) #252v which is very flexible and minimizes transmitted vibration between the riser and the muffler. It is so flexible that you should be able to eliminate the 45 elbow at the muffler.

At the riser, you could use a Trident Silicone Wet Exhaust Elbow to make the sharp turn back toward the muffler. Use a short piece of fiberglass tubing for the coupler and high quality SS T-clamps, especially on the riser since it looks like it is only wide enough for a single clamp.

The use of silicone components results in much longer service life and higher operating temperatures in the event of a raw water pump failure. The Blue Very High Temp silicone is rated at 350F, 100F higher than normal exhaust hose.

I just finished a similar project and was amazed at how much vibration the corrugated silicone hose and elbows provide. Caution, $$$$$$ alert though!

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Old 08-25-2014, 01:53 PM   #13
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I stand corrected. It is being done.
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Old 08-25-2014, 09:07 PM   #14
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Caution, $$$$$$ alert though!

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Holy bloody nightmare. You're not joking are you.

Anyone care to recommend a good supplier that will post international?
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Old 08-25-2014, 09:18 PM   #15
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Bevel cut and glass fiberglass tube to get what you need to fit. Join to mixer and to muffler with six inch sleeves of softwall rubber exhaust hose. Lowest dollar option and still good engineering.
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Old 08-25-2014, 09:35 PM   #16
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Holy bloody nightmare. You're not joking are you.

Anyone care to recommend a good supplier that will post international?
Call Marine Exhaust Manufacturing and Fabrication, Diesel and Gas Systems, and Accessories | DeAngelo Marine Exhaust | deangelomarine.com and ask for Dave.
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Old 08-25-2014, 10:09 PM   #17
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Quote:
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Bevel cut and glass fiberglass tube to get what you need to fit. Join to mixer and to muffler with six inch sleeves of softwall rubber exhaust hose. Lowest dollar option and still good engineering.
Or, if vibration control is an issue, you can use EPDM rubber or silicone hump hoses instead of the straight sleeves. Much, much cheaper than what I proposed before. And, like Ski suggested, still good engineering.

I believe either solution will be much better than the stainless tubing.
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Old 08-25-2014, 10:20 PM   #18
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if you dont want a fabrication job, cut the existing pipe where you wish & replace with hose or similar, several different makes available, here are two with distributors in oz
Trident Marine: Wet Exhaust Hose
http://www.seastarsolutions.com/prod...e/wet-exhaust/
the slicone smooth stuff gives better flow than the rubber corrugated stuff but more $, you choose. the rubber stuff works ok for me (shieldsaust C) but I dont have tight bends
you can surely salvage joining pieces / bends out of your existing pipe if you cant run hose for the whole length ??
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Old 08-25-2014, 10:20 PM   #19
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Holy bloody nightmare. You're not joking are you.

Anyone care to recommend a good supplier that will post international?
Yea, breathtaking isn't it?

Looks like you might be able to get similar Purosil products in Australia here. They will certainly be more affordable without shipping, duty etc.
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Old 08-26-2014, 12:56 AM   #20
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I'm familiar with the Trident 252V hose that has been recommended. It really is great hose. If my memory is correct it can be had in 3, 6, 12 and 60 foot lengths.
I also know a Trident distributor with great prices who ships to Oz, but the forum rules prevent me from saying who it is.
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