Originally Posted by Christian Van H
...Gerr says use Schedule 80 pipe, I measured my old plain steel rusted elbow, and settled on Schedule 40.
I am assuming the elbow is in a wet exhaust and the raw water
exiting the engine
is injected there - ignore the following if not the case.
I have no direct experience of using 316L ss in that particular service
as all the new builds I have been involved in with wet exhausts requiring the injection parts
to be fabricated from new have been large power boats and specialist ss's have been used for which standard fittings cannot be had. But I have had quite a lot of experience with the failure of ss in hot and drying situations where chlorides exist.
SS is very susceptible to corrosion
when exposed to chloride solutions (eg seawater) at higher than ambient temperatures and especially if there are wetting and drying cycles allowing a coating of precipitated chlorides to form.
It is normally even more vulnerable to corrosion in regions where there are stress raisers due to welding.
So, for myself, if going to fabricate such a fitting I would follow the advice and use Sched 80. If it were the case that the engine
manufacturer made their elbow using a resistant alloy (cast in one piece) then I would always use that and swallow my pride regarding the cost, however I understand that the standard fitting in your engine's case seems to be steel so that option is not available.
I also would be interested in any feedback regarding any experiences of long term use of 316L in the application. I have known of a couple and in both cases the experiences were bad - but it may only be because they were bad that I got to hear of them
's for Marinheiro, we posted at the same time so didn't see yours before I hit the send button - is nice to find someone who agrees with me for a change