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Re: Stitch Welding - Staggered vs. Directly Opposite

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Daryl,
First, CSA W59 Section 12 Cl 12.4.14 "Dynamically Loaded Structures" forbids the use of intermittent welds except for "members always in compression ----", and "interconnection always in compression of two or more rolled sections or plates" In all exceptions, 1) the min length of weld shall be 1.5 inches. 2) the max clear spacing between welds shall be 12 x thickness of the thinner part, but not more than 6 inches, 3) at least 25% of the joint shall be welded, 4) A joint with intermittent welds shall have welds at each of its terminal ends (S16.1 covers the length of weld at the ends). Having said that, I have never seen staggered welds on a cap channel ( i have been involved with cranes etc since 1970) but that does not mean you can't do it. In reading your note again, I am not sure if you are referring to the cap channel weld or the sq bar rail weld. For sq bar rails I use a 5/16" fillet (min weld size per W59) x 3" long spaced at 24" o.c. In Europe they usually weld the rail sufficiently that it is part of the built-up beam, whereas here usually the weld is just sufficient to hold the rail in place.
I hope this helps and that I haven't told you something you already know.
Gary

On 3/3/2010 2:22 PM, Daryl Richardson wrote:
Fellow engineers,
I have a crane runway situation for which I would like some opinions. I have a W18x45 runway beam with a C12x20.7 cap channel topped by a 1.5x1.5 square bar for the crane rail. The specified welding is 0.25"; 3"welds @ 12" spacing. The question is "Should the opposite side welds be staggered or directly opposite one another?"
Regards,
H. Daryl Richardson

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