From: Christopher Wright <chrisw(--nospam--at)skypoint.com>
Date: Wed, 18 Apr 01 17:47:56 -0500
>What is the standard I should follow to evaluate the welded connections that
>support the 50-kip counterweights? What percentage of welds should be
>checked? Should they be X-rayed, magnafluxed.....?
Bill's right--the standard is AWS 1.1, but there's more to it. You need
to start with the AISC spec for structural welds for sizing and basic
design issues. You'll also need to set up a means to insure you have
qualified welders and weld procedures. Most of the QA problems I've run
into started with welds specified and supervised by people who know
nothing about welding and weld quality.
Sticking my neck out a little, you'll probably be dealing with fillet
welds performed in the field. If it were me I'd restrict testing to
either liquid penetrant or magneting particle testing of a representative
sample (5-10%)of critical welds. Tests like these are practical, and my
experience has been that NDT has a hidden benefit--welders really don't
like repairing welds and they tend to work more carefully if they think
subsequent examination means grinding out defects and reworking a weld.
Your service sounds very much like critical lifting: highly cyclic and
service load dominated. Weld defects, especially cracks that grow
quickly. kill people in such circumstances, so quality is very important.
You probably won't be doing any impact testing, but you should be using
weld metal with minimum impact test properties. The work goes a little
slower, but I doubt if it'll make any real difference in this case. Your
clients will be laity who work under pressure on a budget and don't care
jack about engineering so be very careful about someone's brother-in-law
who works cheap.
Christopher Wright P.E. |"They couldn't hit an elephant from
chrisw(--nospam--at)skypoint.com | this distance" (last words of Gen.
___________________________| John Sedgwick, Spotsylvania 1864)
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