Gantry Crane Width Extension:

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I'd like to extend the width of my gantry from the current 18' to 24' overall. The main beam is 12", 35# per foot currently. The factory rating on this gantry is three tons and I don't mind derating to two tons if need be with the width extension. The factory did offer the same crane in 24' width with the same top beam so really don't know if a derate would be required.What would be the best way to do perform this operation minus replacing the top beam with one the correct length; add to one end, or stub onto the ends of the existing beam? I'm not opposed to replacing the top beam, but am exploring this modification first.Thanks,SlobPurveyor of intimate unparalleled knowledge of nothing about everything.Oh yeah, also an unabashed internet "Troll" too.....
Reply:I would splice a section to one end. Save making two full pen welds. Do you have room on top to add a truss?Here is the joint prep I would use if using a wire feeder. With SMAW I would open the gap some. Attached ImagesDon’t pay any attention to meI’m just a hobbyist!CarlDynasty 300V350-Pro w/pulseSG Spool gun1937 IdealArc-300PowerArc 200ST3 SA-200sVantage 400
Reply:Another way to beef up a beam is to add to the flanges. Look at a beam being point loaded in the center, like a yard stick. The flanges have to roll to one side, before the beam can buckle. So just add to the flanges.  Attached ImagesDon’t pay any attention to meI’m just a hobbyist!CarlDynasty 300V350-Pro w/pulseSG Spool gun1937 IdealArc-300PowerArc 200ST3 SA-200sVantage 400
Reply:This is along the lines I was thinking also and thanks for the confirmation. When I made the crane hydraulic drive I lost almost 20" of inside clearance which was marginal prior to doing this. Opening it up 4' will more than make up for the shortfalls now.Thanks again,SlobPurveyor of intimate unparalleled knowledge of nothing about everything.Oh yeah, also an unabashed internet "Troll" too.....
Reply:CEP is the best way. If it is bending and deflects weld a piece of channel legs down on the top in the center say 10 ft.
Reply:Originally Posted by Pavinsteelmanweld a piece of channel legs down on the top in the center say 10 ft.
Reply:By placing the channel  toes down, you place the C channels web at it's highest possible point, putting the majority of the steel as far from the neutral axis of the beam as possible. In effect you have made that section of the beam "taller" vs simply adding more material to the flange as your diagram in post 3 shows. "Best" solution would be to install a full length taller beam of at least equal or greater weight per foot. That would give you the most resistance to bending. Trussing the top of the beam would also give similar results if done properly..No government ever voluntarily reduces itself in size. Government programs, once launched, never disappear. Actually, a government bureau is the nearest thing to eternal life we'll ever see on this earth! Ronald Reagan
Reply:Originally Posted by DSWBy placing the channel  toes down, you place the C channels web at it's highest possible point, putting the majority of the steel as far from the neutral axis of the beam as possible.
Reply:That way increases beam strength without greatly increasing beam height. Typically you'd want to do that in existing conditions where say you needed to increase the beam strength to handle additional loads later, say a new larger AC unit on a roof where removal of the existing beam isn't possible or clearance issues prevent using a larger beam and lowering the lower flange. It works, but isn't very efficient.For example a W 8x28 will carry 21.5 kips over 18 ft roughly ( heaviest small beam in my structures book) ( 8" tall, Flange width 6.5"  flange thickness .465) A W 14x22 carries almost the same load over that distance, ( 13.75" tall, Flange 5" wide .33" thick)  and a W 12x26 carries almost 3 kips more and a W 14x26  almost 4 kips more, close to 20% more than the heavier 8" beam does. A W16x26 will carry almost 28 kips over that distance, almost 30% more and it's still lighter than the 8" beam.( 15.69 tall, flange width 5.5", thickness .345")You will note that the 8" beam has more steel top and bottom compared to the 16" beam, yet the 16" beam is significantly stronger and lighter overall. This is because the material top and bottom that resists bending is farther from the neutral axis of the beam, thus it's loaded more efficiently. It's just like a lever. Mass x distance. You can use less material if you put it farther out the lever arm ( a bit over simplistic but easier to understand for most.).No government ever voluntarily reduces itself in size. Government programs, once launched, never disappear. Actually, a government bureau is the nearest thing to eternal life we'll ever see on this earth! Ronald Reagan
Reply:I don't remember why, maybe I was never told. But I had to weld flatbar to the bottom of the structural beams at Sea-Tac airport. Decking was on the top flange, so I welded flatbar to the bottom flange. The worst part was scraping all that fire protection off the beams, before welding! Don’t pay any attention to meI’m just a hobbyist!CarlDynasty 300V350-Pro w/pulseSG Spool gun1937 IdealArc-300PowerArc 200ST3 SA-200sVantage 400
Reply:Man CEP, I had to do the exact same thing at DuPont.  It took me longer to scrap all the fire protection off than to do the welds.  That's some nasty stuff!
Reply:Under the airport where all the conveyors are. One time a fire protection contractor dropped visqueen from the ceiling to block off this large section to spray. Had to protect the baggage handlers, but the he!! with the construction workers. It looked just like it was snowing inside the building! I hate that stuff, it gets stuck in my throat!Don’t pay any attention to meI’m just a hobbyist!CarlDynasty 300V350-Pro w/pulseSG Spool gun1937 IdealArc-300PowerArc 200ST3 SA-200sVantage 400
Reply:Yea I hear ya man.  That stuff is nasty!
Reply:Whoever checked our runways had us do it on a 90 ft span 15 ton runway to bring it up to 30 tons and had to be braced to the building frame for side loading sway on a outside runway. Pulled up the track and welded a C18x58 toes down and replaced track.
Reply:I went out to the shop, and dug through the scrap pile. How's this?  Attached ImagesDon’t pay any attention to meI’m just a hobbyist!CarlDynasty 300V350-Pro w/pulseSG Spool gun1937 IdealArc-300PowerArc 200ST3 SA-200sVantage 400
Reply:If the wider factory version uses the same size of beam, I'm not sure you need much more reinforcement? If it were mine, I'd just add a piece on one end and drill new holes to bolt it on. Being that it should be easy to take the top beam off, you could extend it and easily flip it for flat position welding an all sides. This would also allow you to back gouge and/or back grind all the welds for full penetration. Just for piece of mind weld a flat bar on the top.
Reply:Lots of good and prudent information in this thread I'd not even thought about. The company I'd purchased this crane from years ago actually had two being this one, and another like it but 12' in width. The company uses the same top beam for all they manufacture in the three ton rating. The top beam is retained by beam clamp wedges only and not via drilled flange. Removal of the beam via either forklift, or another crane is easy if the two vertical members are supported from falling. I'm going to be taking it apart to both widen, and increase the elevation shortly but only wish to dismember it a single time. I've already acquired material for the vertical legs and will purchase additional beam now. It will be welded in the horizontal position on support stands for ease of the job using my mig machine. I too am uncertain about adding additional support as I really never apply much over two tons to the hook but do wish to retain the original ratings. My hydraulic piping mounts are run on top of the current beam, but the mounts could be cut free, additional support welded to this beam, and the mounts rewelded down. Thanks for the assist.SlobPurveyor of intimate unparalleled knowledge of nothing about everything.Oh yeah, also an unabashed internet "Troll" too.....
Reply:When making the splice be sure to keep track of how straight it is with a straight edge or piano wire. Don’t pay any attention to meI’m just a hobbyist!CarlDynasty 300V350-Pro w/pulseSG Spool gun1937 IdealArc-300PowerArc 200ST3 SA-200sVantage 400
Reply:I'll probably "true up" the beam's butt ends in my band saw, bevel the edges, then clamp for alignment with straight edges on the top and bottom flanges, and apply a few good "tacks" to hold alignment while welding. I'll have to grind the top of the bottom flange flat as the hoist trolley wheels ride over this area. Other than that, probably won't have to do much else to finish except paint. Thanks again,SlobPurveyor of intimate unparalleled knowledge of nothing about everything.Oh yeah, also an unabashed internet "Troll" too.....
Reply:You need to keep track of it while welding! You'd be surprised how much welds will pull a beam out of alignment.Don’t pay any attention to meI’m just a hobbyist!CarlDynasty 300V350-Pro w/pulseSG Spool gun1937 IdealArc-300PowerArc 200ST3 SA-200sVantage 400
Reply:When I worked building skids, they'd clamp another section of beam on when extending or splicing the beams. I think once you have it tacked good you want to weld the web first but having a piece clamped on will hold it straight until the last welds which would be the outside flanges where you could grind them out.
Reply:I agree on heat pull. I'm a fan of opposed stitch welding myself rather than continuous. I really learned that lesson on a semi trailer neck once when not paying attention and got to cut it apart to do it again. Will try to not make that mistake again!! I agree with welding the webs first after tacking.SlobPurveyor of intimate unparalleled knowledge of nothing about everything.Oh yeah, also an unabashed internet "Troll" too.....