On Apr 5, 2007, at 5:27 AM, Steve McKenzie wrote:
> Generally for us pseudo-amateurs, we stick to the marine bronzes
> and the
> occasional bit of copper-exotic unless unusual circumstances
> prevail. 316(L)
Other people's experience is the best guide for corrosion prediction.
My own experience, for example, the part of me that gets the creeps
walking through dark woods, says that corrosion problems are only
solved by invoking dark powers.
Too many variables, I think. I spent a long time using plain old 304 stainless in intermittent sea water service, until one day someone noticed some cracking in a ballast tank weld. When we took off the paint all the welds appeared to be starting to dissolve. Only the welds. After a lot of spading through old memories, and some test results, it turned out the culprit was too much welding heat, which had sensitized the welds. That wasn't the case with a leaky fitting someone found in a forged tube fitting. The leak wasn't around the fitting--it was a tiny hole all the way through the wall. No welding or anything and no repeat failures after the fitting was replaced.
Most of this service involved well-maintained equipment used for undersea operations support, and our design practice benefitted heavily from general experience and design practice for military submersibles. Everyone had the quickie charts showing the galvanic series and wastage rates for various materials in various tests, but they were only the beginning. People tended to stick with what they knew.
Christopher Wright P.E. |"They couldn't hit an elephant at <a href="/group/PipingDesign/post?postID=35ZTmnhBz-im3z0k5WTcGPehV395Zhrh93k6nrxOaBgnVsKrIRscTYsMbR-EpKriXRQbuvrUfkd-i10">chrisw@skypoint.com</a> | this distance" (last words of Gen.
.......................................| John Sedgwick, Spotsylvania1864)
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