> I have a situation where we specified an aluminum
> railing system consisting of welded members. The
> system is manufactured in china and shipped to the US
> for installation. what kinds of tests should we
> request to insure that foreign welding is appropriate.
Tough job. If it were a pressure vessel job, I'd request copies of
all the QA documents, the welding procedures and procedure
qualifications. Then I'd probably do some quick met testing over here
to make sure the materials themselves are what the supplier said they
were. I'd also request design documents showing that the original
designers knew enough about aluminum design. And because I'm a bit
nosy, I'm real curious why you specified the system without some
guarantee that the system would be welded properly and that it would
meet the Aluminum Association structural spec. If you've already
contracted for the railing, any testing you do may be irrelevant if
it's not in the original purchase documents.
Welding aluminum isn't exactly rocket science, but it has to be done
properly or you get serious problems. Aluminum undergoes a
significant loss in strength when it's welded and there may be a loss
in ductility depending on the welding consumables. There can be
distortion issues and because aluminum has a low melting temperature,
sometimes there are procedural problems.
OTOH, I've been riding a bike with a welded aluminum frame and put
about 7000 miles on it and it's done pretty well. The bike was
designed in the US and made in Taiwan, although it appears that each
frame was welded and heat treated to restore the strength of the
aluminum, presumably by the manufacturer. This isn't your everyday
approach to aluminum welding but it seems to work out.
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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