On May 28, 2006, at 10:05 AM, Ken Nisly-Nagele wrote:
> I've not heard it said outright, but my perception is many "seasoned"
> contractors and engineers think that carbon steel does not fail in
> steam
> service due to fatigue.
Nothing does not fail in fatigue, provided the stress high enough and
you put enough load cycles on it. That goes double for materials
commonly used in steam service where toughness is overlooked. Weld
defects are notorious sources for fatigue failure in carbon steels
because any crack will grow under cyclic loading. Even without a crack,
enough stress ccycled enough times will cause a fatigue failure, and it
can happen with anything.
That said some materials are a lot less susceptible to fatigue failures in some services. But A-106 or A-234 aren't immune. Al lot of the kinks have been worked out of carbon steel steam piping and such failures don't happen often these days. But they can happen and they do.
Remember that all generalizations are false.
Christopher Wright P.E. |"They couldn't hit an elephant at chrisw@skypoint.com | this distance" (last words of Gen.
.......................................| John Sedgwick, Spotsylvania1864)
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