> Pipers and millwrights can weld much better than structural welders.
Although I completely agree, having worked around a lot of ASME Code
fabrication for a lot of years, it's fair to say that if structural
welders were subject to the qualification and QA requirements
mandated by the piping and pressure vessel codes, they'd be just as
good. The moment connection failures after Northridge would probably
not been half so widespread either.
A big part of the problem is that too many engineers don't take
welding seriously. As undergraduates we're taught that welds are
those perfect little triangles with a simple minded design rationale
that makes them seem like another kind of beam. 'Tain't so, McGee. If
we're lucky enough to get some exposure to metallurgy we learn a
little about heat-affected zones, but nothing about welding itself--
how the welder controls the molten metal or thermal distortion or all
the bad things that can happen if things aren't done properly. Coming
from ASME Code fabrication, the first time I ran into the term 'pre-
qualified joint,' my blood ran cold. More of us ought to get out to
weld shops and watch field welding and maybe try running a bead.
> they weld huge steel pipes together with butt splice complete joint
> penetration bevel welds, in the middle of a Wisconsin winter, all
> of the time... These pipes carry water and steam and may not have
> the stress in them that a wide flange butt welded will have
Just so you know, piping codes don't permit welding when the
temperature is too low or when the joint might be exposed to rain or
snow melt. And the stress levels in pipe are about what you'd expect
in beams except there's no plastic reserve and pipe stress is
statically determinate and fracture critical. A running crack in a
steam line can spoil your whole weedend.
Christopher Wright P.E. |"They couldn't hit an elephant at
chrisw@skypoint.com | this distance" (last words of Gen.
.......................................| John Sedgwick, Spotsylvania
1864)
http://www.skypoint.com/~chrisw/
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