I screwed up, help me learn from it.

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Today a cantilever rack that I built, was carrying about 700 lbs on it when it snapped in half  and came dam close to crushing my arm. It actually landed on my arm but some 4" drops of pipe stopped it from falling farther.The rack failed because someone had knocked the cap off, water got in, turned to ice and split the pipe. The crack waited patently for me to reach under it and snapped in half.I work for a fence company and made the rack for storing used top rail, 21' x 1-3/8, 1-5/8, a mix of .065 and ss40.The rack is about 3'6" high by 24" deep. 2 racks total one for each end of the top rail. They are made of used fencing.2-1/2" ss40 for the frame, 1-5/8" ss40 for the arms.LessonsWeld the caps on so water can't get in the pipe.I didn't do the math on how much this would weight when full.Using 2 singles instead of 2 doubles for pipe this length was a major brain fart.What I think I should have done.2 double racks (thats what I normally do for top rail.)3" ss40 for the frames, 2-1/2" ss40 for the arms.According to hooverfence.com/catalog/chart.htm that would give me about a 2x safety margin when full. Any advise is welcome.Adam
Reply:My only advise.. Move somewhere warmer You already know to make it heavier and weld the caps on, I can't think of anything else to add.Airco Ac/Dc 300 HeliwelderMillerMatic 200 (stolen)Miller Maxstar 150STLMiller AEAD200LE (welding and generating power) Hobart MIG
Reply:I don't think I have ever seen steel "break" before. . . .I've seen it shear, kink, bend, rip (same as shear?), but never seen a "break" like that. like a tensile break is what happened, right?bosses stuff:trailblazer 325maxstar 200my stuff:sa 200fronius transpocket 180100 amp Lincoln w/f97 f350 DITKevin
Reply:Overloaded it by this much? If you can't use larger diameter pipe use more at closer intervals. You already know this. If your the go to guy for fab work in this outfit it is all on you. When you rebuild it do it right. Your responsible for every person that even walks by your work. If the boss don't agree get it in writing that the particular design doesn't work or whatever(try not to get fired). This could have easily killed you or an innocent.  That should have been made with 6" heavy wall at 4'oc to hold that. Probably more. You've got to account for everything like wind load, snow load and Unicorns looking for a pipe rack to land on. I'm glad you care enough to ask about it. Hope I helped a little.Arcon Workhorse 300MSPowcon 400SMTPowcon SM400 x 2Powcon SM3001968 SA200 Redface1978 SA250 DieselMiller Super 32P FeederPre 1927 American 14" High Duty LatheK&T Milwaukee 2H Horizontal MillBryan
Reply:That's exactly what happened. Started with a vertical rupture. Right at the joint where it was welded. Heat boys, heat. Originally Posted by 92dlxmanI don't think I have ever seen steel "break" before. . . .I've seen it shear, kink, bend, rip (same as shear?), but never seen a "break" like that. like a tensile break is what happened, right?
Reply:I would be checking the others.
Reply:Ice jacking is a common problem here keeping the water out is one thing but makeimg sure the water has a way out when it gets in is another we drill 3/16" drain holes in the lowest point of all structural tubing.
Reply:that looks like some bogus pipe with the split on what appears to be the seam. looks more like cast iron or aluminum at the break, it must be some low bid grade of steel to begin with.i.u.o.e. # 15queens, ny and sunny fla
Reply:pretty amazing what ice can do isnt it. I've seen copper rated for use at 500psi stretch to double its original diameter and rupture from a little ice, also seen it lift entire buildings to the point where the doors don't open, windows seize up and the drywall and foundations crack. Remember, it was an ice cube that sank the titanic. Amazingly powerful stuff.
Reply:Originally Posted by docwelderthat looks like some bogus pipe with the split on what appears to be the seam. looks more like cast iron or aluminum at the break, it must be some low bid grade of steel to begin with.
Reply:Originally Posted by gnm109It appears to have been overloaded as well......
Reply:Originally Posted by kingneroIf it weren't, it wouldn't have cracked ??? But I guess that's not what you ment? Why would you say that it has been overloaded (apart from the obvious tell-tale that you can see the inside of that pipe, of course) ?
Reply:Is this used oilfield pipe?
Reply:It was 65 pieces of 1-3/8, I figure around 700 lbs.Even if it hadn't cracked from the ice, it still would be to much weight to be safe.I want to have at least a 2x safety margin.Having said that, the way it cracked still seems strange to me.I agree with gnm109 that the grain looks closer to cast iron and it makes me wonder about the other pipe I have.What does everyone else think, and how can I tell if the other stuff I have is good?BD1The first thing I did was check the others.PipelinerThis is all old galv fence posts probably 50 years old or so.BTW it did split at the seam(I assume it always does), you can see what the unbroken weld looks like in this pic.Last edited by Blueduck600; 01-21-2014 at 11:45 AM.
Reply:Ok I was just wondering about the pipe the rack was made from.
Reply:So the reason the fracture surface looks like cast iron is likely because of how fast it broke and the cold environment.  Ice caused the tube to split right along the welded seam.  The overload caused the crack to start at the point of highest stress and run around the circumference of the pipe.That fence pipe is, "...What it is...".  It's probably not an ASTM grade of structural tube or pressure pipe.  OSHA and most safety personnel would call what you had a Near Miss.  You got lucky, which I'm sure you already know.  In your shoes I'd do one of 3 things:1-Buy an engineered rack from someone else with rated and labeled load capacities.  Shift the liability for design to someone else with the knowledge and experience to engineer the product. Ensure that the people storing material on the rack don't overload it.2 - Pay an engineer to design a pipe rack and provide a safe load rating for it.  Then make certain that the people storing material on the rack don't overload it.3 - Build your own rack.  Pay an engineer to evaluate the structure and give you a load rating with appropriate safety factors.  Label the rack with the load rating.  Ensure that the people storing material on the rack don't overload it.All three options are going to cost you some money, one way or the other.  My guess is when you factor in the design time, fabrication time, and engineering fees, option 1 will turn out to be the least expensive.Option 2 is the next best choice if you can't find a ready-made product that meets your needs.Option 3 might be cheaper than option 2, but you may be surprised at the end and find out you built way too sturdy, or not sturdy enough...Benson's Mobile Welding - Dayton, OH metro area - AWS Certified Welding Inspector
Reply:Originally Posted by abecIce jacking is a common problem here keeping the water out is one thing but makeimg sure the water has a way out when it gets in is another we drill 3/16" drain holes in the lowest point of all structural tubing.
Reply:A DAB will do, walkerweldThanks for verifying that the grain is from the cold temps.Unfortunately there is no chance of my boss buying new racks or paying for an engineer. The quality of what I build is well above what my boss wants, but he is willing to tolerate it(he has actually said this). He once wanted me to build an 8' tall cantilever rack for bunks of 4x4x8 fence posts. that would be 6 bunks, and bolt it to a cinder block wall for strength. I was horrified and flat out refused. He wasn't happy but he got over it.Generally what I'm doing is replacing old racks that are scary bad with mine that are at LEAST 2x as strong. This one was an exception and it won't happen again.I will use drain holes in all future builds and in the ones already built. Thanks.
Reply:Blueduck,I hear what you're saying about the boss not paying for engineering.  I hope no one in your company ever comes to regret that kind of thinking.  It's been my experience that a sound design from an experienced professional is a lot cheaper than OSHA, workman's comp, and all the other costs that come when someone gets hurt at work...Enough preaching for now...My #2 suggestion is to look at what is available for purchase, and copy someone else's design and use their load rating.   If you can't buy the engineering expertise, you can at least borrow it.#3  You can also work your design so their are no failure critical connections.  Build it so that multiple joints have to fail in order for a catastrophe to happen.  No cantilevered members.  Use Diagonal bracing underneath to support the load.  Oversize the main structural columns.  #4  Build 2 smaller racks to hold the material.  Less load on each rack means less chance of a problem.  It'll take more space, but maybe that's not a problem...Benson's Mobile Welding - Dayton, OH metro area - AWS Certified Welding Inspector
Reply:Originally Posted by Blueduck600A DAB will do, walkerweldI will use drain holes in all future builds and in the ones already built. Thanks.
Reply:Originally Posted by Blueduck600It was 65 pieces of 1-3/8, I figure around 700 lbs.Even if it hadn't cracked from the ice, it still would be to much weight to be safe.I want to have at least a 2x safety margin.Having said that, the way it cracked still seems strange to me.I agree with gnm109 that the grain looks closer to cast iron and it makes me wonder about the other pipe I have.What does everyone else think, and how can I tell if the other stuff I have is good?BD1The first thing I did was check the others.PipelinerThis is all old galv fence posts probably 50 years old or so.BTW it did split at the seam(I assume it always does), you can see what the unbroken weld looks like in this pic.
Reply:Looks like the design of the "cantilever" rack verticals is way too light duty.
Reply:I'm in an area that freezes too, if I'm making a rack like that for outside, I'm using channels or beams.  Nothing that can fill with water and freeze.
Reply:What scheme do you use for the feet of the support legs?  To prevent water from entering you still need to cap the open top end of the legs, but with a solid welded plug, or a slip cover cap that is welded in place so it can't be dislodged by a careless move when working pipe in and out of the racks.Drain away provisions still need to be used in the feet.  I have observed outdoor racks that were secured to concrete pads having embedded anchor studs for attaching the feet of the racks to the pads.  In those venues, the bottom end of the vertical rack legs were welded to a mounting flange, but the flange had an opening in the center so that the leg could drain and never become a containment vessel.  Furthermore, a nut was run down onto each anchor stud first before the rack leg was placed over the studs. The nut became a spacer that positioned the mounting flange above the concrete pad, and also doubled as an adjustment means for aligning the legs to a true vertical.  The space between the concrete pad and the flange assured good drainage for the life of the structure.Even if the racks you build are free standing, you can incorporate a good drainage scheme into the feet that are unlikely to clog.
Reply:Well?Lots of thoughts on the Ice and Cold causing the pipe to snap like brittle Cast Iron.In the mid-80's I used to pick up lots of old Pennsylvania Oil Field pipe to sell to the Farmers for Gates, Stanchions and such. Well Tubing is steel and will bend, the old pipe line pipe, some would bend and lots of the REALLY old pipe would snap just like that one did. Most times to sort through it, you could hit it with a hammer, if it rang, it would bend, if it made a thudding sound, it went in the Shear. If it was brittle, it snapped off, if it was good, it sheared and went back on the Farmer pile.Cheap old pipe will get brittle from weather and old age.All this talk of cold weather has me wondering if you ought to be pre-heating your weld area before welding.  The drastic change from cold temps to hot, post welded temps, and then back to cold temps has a way of weakening metal.  In the pressure tank business, we are required to preheat everything, maintain heat for the duration of welding, and control how quickly the welded piece cools off.  You probably do not need to go crazy with the process but a little preheating might make the weld and the metal surrounding the weld stronger in the long run.  Additionally, I second the notion that your vertical pipe, the one that snapped, was way too thin for what you were building.  Consider using I-beam if you have any laying around.  Thats what we used for the main frame at work.Matthew MortonTexas A&M '06Logsdon Seminary '13"Who Dares Wins""AFTF""WH2PH"SA 200 (Code: 5337)TB 302CP 302 w/22A Wire FeederMillerMatic 200Miller Syncrowave 200MillerMatic 252BurnTables 4x4 CNC MachineHypertherm 65