Tell me if this is overkill

admin

First I don't have pics since this is a work project.I've been building a boom to hold an overhead light and a ventilation tube and air hose.  The material I'm using is 01-CS 2"x3" angle with the top span being 10' in length while the back is 3' and the bottom support is 6'.  I've taken 1" inside diameter stainless pipe cut into 6 pieces for hinges and stainless steel bar for the hing pins.  The back plate for the other side of the hinge are two 6" wide C channel 1/4" thick welded to a steel H beam, using the C channel allowed this to be mounted to the face of the H beam so that it would not interfere with electrical conduit already there and to run additional conduit or wiring if needed.At the end of the boom arm I'm attaching a frame for the light made of a 2"x2"x12" angle with 2 1.5"x1.5"x 10" angle to form an arrow attached to a 1/8" plate 2'x8" plate for a total length of the boom arm to be 11'5".  The light fixture is a 4 bulb 4' long fixture with internal ballast, the ventilation line is a 6" round flame resistant wire reinforced tube and the air line is a standard industrial shop pneumatic line and there's a 30' weld lead also.All beads on the frame are tig with 2 bead reinforcement, the hinge sleeves are 4 bead reinforced and the C channel will also be 4 bead reinforced with the top channel being 12" in length and the bottom 8" in length.  So is it overkill?  I'm leaning towards no because I believe in building it tough and to last a long time.Welding Supervisor Department of Corrections.
Reply:Not sure what this is for, but a few thoughts about how the Navy and the military in general does things. They have specs written for everything... Often it's easier to go with an existing spec rather than go thru the process to approve a new spec even if the existing spec is overkill. Those specs often have to cover items that may be used at below -60 in Alaska to +140 in the desert. Add in special requirements like subs and aircraft where material or assembly failures can be catastrophic and some times things that don't make sense start to. Toxic smoke might not matter that much in your house, but it's a different story in a sub at 1000 ft where you can't just open the window. Designs also often are made to take in worst case scenarios, like battle damage even if the item itself isn't critical. Then there's always the "make do with what you have" mentality that's often a necessity in the military as well.  It is often easier to use 1/4" material than ordering 1/8" when you have than going thru all the paper work to justify something thats not standard issue to your unit.None of this may apply to your situation, but it's something to think about where you work. There were a great many ships saved or lost in WWII based on the care taken at the yard by workers..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:This is a shop built purpose tool and not something for ship use.  The current overhead lights are12ft up and are minimal at providing light, there's a door right next to me that opens outside but its coming from the side and to glaring in the darkened interior.  In regards to the actual materials for the ships themselves each item is built to spec and if we have to wait for a specific thickness of plate or a specific alloy then we wait and go to work on something else.  I've also stopped work on items that I felt were not right and have gotten the problem corrected which makes me feel pretty good about what I do.Welding Supervisor Department of Corrections.
Reply:A couple of thoughts in no particular order.Do NOT weld onto the existing building structural steel!  Not sure if your description had you welding to the H-beam in the building.Related to the building steel, for anything other than very light-weight stuff, be careful of using the building structural steel as part of your 'structure'.  Sometimes that is no problem at all.  Other times, you can end up putting some funky sideways load on something that was not ever designed for a sideways/funky load.Want to hang/attach something onto the building's structural steel?  More than just a few pounds worth?  Get the building engineer/manager to figure it out and 'approve' it.  (probably overkill in your case, but I don't know what this sideways cantilevered boom of yours is going to do to the building's column.)Although angle iron is useful and handy for lots of things, I'm always very leary of using angle iron for anything 'structural'.  Mostly because angle iron will ever so slightly twist/torque as it is loaded and deflects.  And when (not if, but when) that slight deflection twist occurs the angle iron will often no longer have a leg vertical to resist the vertical load (or horizontal to resist a horizontal load).  Which means that what was formerly just fine now suddenly and catastrophically collapses.And a cantilevered 10+ ft long piece of 2x3 angle iron with weight at the end (big light fixture plus hose reel that you then tug on plus duct/fan and all) is not what I would consider all that good.Closed shapes are 'better' because they don't undergo the same catastropic twisting under deformation loading that an open shape like angle iron does.  Hence hollow tubes/pipes instead of angle iron.  Heck, even making up a closed shape of that angle iron into a hollow triangular 'beam' would be better from the standpoint of eliminating that twist-on-deformation that angle iron does.Watch out for loaded up stainless steel on stainless steel, especially if they are the same/similar alloy.  Stainless on stainless can gall (micro-weld itself to itself under pressure/load).  Think stainless nut on a stainless bolt, which is sort of why never-seize was invented.    (BTDT, ended up using the biggest cheater bar we could scrounge and hauling on that until we ended up snapping the bolt, because the nut and bolt had achieved a Zen Oneness-With-The-Universe-And-One-Another and were NOT coming apart.)  The best laid schemes ... Gang oft agley ...
Reply:sounds   to me  like    you have  a good understanding      and  common sense   to build  most anything  safely   ,   and    get help when needed   to  make things   right  .         the material  u mentioned    sounds like  good sizing  .Also would like to mention >all though  u prolly  already knowInnovations are what i leave behind for History
Reply:I could box the the angle in with a long and thin piece of plate about 1/16" to minimize added weight if needed.  I got approval for the installation the beam and it is welded.  The upper hinge is the largest and is within 6 inches of the horizontal beam.I'll see what I can do about pics but it will take some red tape to get it.Welding Supervisor Department of Corrections.