Crawler set ups are what I have seen (large? 48" to 80" girders). This allows access underneath the Flg 2 Flg braces and the Flg to webs just have to be interrupted and figured into the BID. But, I have only been in 2 AISC, D1.1, D1.5 shops.

Chris

Most of the time, those temporary stays are not allowed. 

All of the fabrication facilities that I inspect as a third party QA inspector, who weld with the flanges vertical and the web plate horizontal, use some sort of "squeezer" and wedges to hold the flanges aligned.  Some also tilt the flanges to a "secret" number of degrees, so that the flanges are slightly tilted after the first side is welded and are perpendicular after the second side is welded.  Many shops flip the beams when placing multiple pass welds, so that the flange tilt comes out perpendicular.  Most shops do extensive tacking on both sides of the web prior to SAW welding.

I have seen some shops that weld with the web vertical, and they all tack weld both sides and top and bottom prior to running the crawler carriages with the wire feeders down both sides simultaneously.  I have seen only one shop do web vertical welding fabrication without a squeezer.

Swept and cambered tub girders are always done in a special squeezer.

In bridge girders, tilt of the flange is often a QC/QA issue, but not the warp of the flange, because the thickness of the flanges is adequate to avoid exceeding the acceptance criteria limit for warp and tilt of flange.  I usually see web warpage problems when the web plate is less than 9/16 inch thick.

In building girders, many times the flange plates are relatively thin, and I often see excess warpage.  Again, I also see web warpage problems when the web plates are less that 9/16 inch thick.

Fabricators that regularly fabricate welded beams usually have a Dart Welder to weld the stiffeners to the webs.   Is this type of fabrication something your company is just getting into?

Joe Kane

Metal building manufacturers fabricate beams by SAW web plate to flat bar flanges on an assembly line basis. The parts are held together in a large, adjustable, pneumatic jig during SAW with very little to no distortion, even though the beams are only welded on one side.

Here is an example of a CONRAC fully automatic machine, otherwise known as a "Pull Through" beam welder. With this machine, an operator simply feeds pre cut parts into one end and the machine spits a completed beam out the other end. This set up is rather expensive, with a basic model starting around 1 million dollars.

http://www.yodermachinery.com/machine.asp?Index=0

The last company I worked for used a KENTEX semi automatic machine that worked very well but was somewhat labor intensive as operators hand load the parts into the jig and tack them together prior to turning on the automatic SAW. This macine is more economical at a starting price for a basic model around 250K.

http://www.gokentex.com/pages/beam_welding.htm

Here's another link for a typical pull through beam welder.

http://www.steelexnetwork.com/beamweldingline.html

Tim