Exhaust Elbow S/steel grade

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richardabeattie

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I'd like to buy a stainless steel elbow for my raw water 2GM20 so I asked the supplier - ben@exhaustelbow.com - why he does not make them from 316 stainless. He agreed it would be better than the 304 that he uses but said he could not get 316 tubing of the right size and that 304 was good enough to give long service - a lot better than Yanmar's expensive mild steel version. What does the panel think?
 
richardabeattie said:
I'd like to buy a stainless steel elbow for my raw water 2GM20 so I asked the supplier - ben@exhaustelbow.com - why he does not make them from 316 stainless. He agreed it would be better than the 304 that he uses but said he could not get 316 tubing of the right size and that 304 was good enough to give long service - a lot better than Yanmar's expensive mild steel version. What does the panel think?
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Yanmars elbow is not mild steel. It is stainless. However the aftermarket ones are cheaper. 316 is potentially better, but the problem with these elbows is not the grade of steel but a combination of the positioning of the welds (and the quality of welds) together with the way the water is injected.
 
Tranona said:
Yanmars elbow is not mild steel. It is stainless. However the aftermarket ones are cheaper. 316 is potentially better, but the problem with these elbows is not the grade of steel but a combination of the positioning of the welds (and the quality of welds) together with the way the water is injected.
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Can you expand on the specifics of the Welds and water injection?
 
The inner tube is welded into the outer, and the injection tube is also welded in. It is really difficult to get good welds here and they are sprayed with hot salt water which can cause corrosion. Also the hot salt water can be sucked back into the inner tube when the engine shuts down leaving the whole area damp. They corrode either at the welds or perforation of the inner tube.
 
Don't know, but probably not 316. Not polished and shiny like the aftermarket ones. Try a magnet on yours.
 
Agree about the welds. I removed mine this winter, it looked perfect from the outside but the inner tube fell out once it was off the engine. Both parts were perfect apart from the welds which gave way. I know it wasn't original but was a Yanmar one. The previous owner had replaced it sometime before I bought the boat.
 
On the other hand my 1GM from 1987 was still fine when I sold it in 2010 and think it is still going in another boat.
 
My original Yanmar manifold is definitely made from a 300 series stainless steel. It failed last year at about 2200 hours, 12-13 years. It failed as Tranona says, the complex welds between the inner and outer tubes and the flange began leaking seawater.

There is probably no great advantage in going to 316 over 304 as I see very little pitting on the old manifold. What I suspect would help, and I believe this has been suggested to Ben, is to use a better grade of filler rod, such as a low carbon version of 316 with titanium or niobium. This prevents sensitisation, the main reason that the welds fail.
 
vyv_cox said:
My original Yanmar manifold is definitely made from a 300 series stainless steel. It failed last year at about 2200 hours, 12-13 years. It failed as Tranona says, the complex welds between the inner and outer tubes and the flange began leaking seawater.

There is probably no great advantage in going to 316 over 304 as I see very little pitting on the old manifold. What I suspect would help, and I believe this has been suggested to Ben, is to use a better grade of filler rod, such as a low carbon version of 316 with titanium or niobium. This prevents sensitisation, the main reason that the welds fail.
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I used schedule 40 2" 316 stainless threaded pipe fittings screwed in to an ASAP water inj fitting. The weld to the flange was in a "dry" area. It has worked well and is now nearly 2 years old. It looks good, professional and was only a quarter if the price of a VP one.
The pipe fittings came from a factor in Chester and are relatively cheap and easily obtainable. Contrary to what Jumble Duck said it is a professional job and works well!
https://www.colglo.co.uk/productlist.php?category=SS_Fittings_Flanges_316
S
 
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I'm in the process of replacing mine with 316 stainless.
Mine is the high lift elbow though so more expensive but better in preventing water syphoning. French Marine quoted me £243 + VAT for the standard Yanmar elbow 124070-13520.
I getting the elbow fabricated for about £100.
PM me if you want a drawing and where I got the parts
 
richardabeattie said:
I'd like to buy a stainless steel elbow for my raw water 2GM20 so I asked the supplier - ben@exhaustelbow.com - why he does not make them from 316 stainless. He agreed it would be better than the 304 that he uses but said he could not get 316 tubing of the right size and that 304 was good enough to give long service - a lot better than Yanmar's expensive mild steel version. What does the panel think?
Click to expand...

From bitter experience, 304 ss is NOT good enough. I had an elbow made in allegedly 316 which lasted just 3 years before it perforated like a pepper pot. Under pressure the fabricator admitted that it was 304 not 316 but refused a refund. The refund popped through the post shortly after his summons to the Small Claims Court reached him.

316 or nothing, there are lots of good fabricators out there who want the business.
 
Len Ingalls said:
Possible source of SS elbows.
http://www.ebay.com/sch/haileyseye/...e=STRK:MEBIDX:IT&rt=nc&_trksid=p2047675.l2562
Click to expand...

How do I fit this to a 1GM10, for which it is listed?

$_57.JPG
 
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