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Recent content by toothless48

  1. toothless48

    Two disconnects on one enclosure

    Hello, My question is whether NEC or other standards prohibit this design choice: We have an industrial electrical cabinet that receives 480V power from an electrical drop. There is a knife switch disconnect that kills power to the whole cabinet. We would like to be able to disconnect just the...
  2. toothless48

    Looking for advice on a validation procedure for E-Stop buttons tied to a safety PLC.

    Hello, I am working on a small to medium-sized automation system, and I am currently writing the commissioning procedures, particularly ones related to functional safety. I am somewhat new to it. The procedure I have written out is based on some examples I found while searching the internet...
  3. toothless48

    How to dampen noise coming from a thin-walled rectangular aluminum extrusion

    @BrianE22 Thanks for the input. Good to know that it helped. We will be much lower in amplitude than a shaker table, so it might be a solution. @IRstuff That is an interesting point, didn't think about that at all. This is something we are going to have to access.
  4. toothless48

    How to dampen noise coming from a thin-walled rectangular aluminum extrusion

    Hi, I am working on a project with thin-walled aluminum extrusions (4" x 4" x 1/8" x 6' LG) that are bolted to a large machine that produces a lot of vibration. The concern (not yet proven, but suspected) is that the tubes will act as an acoustic chamber and produce a lot of nuisance noise...
  5. toothless48

    Concrete strength for a lifting point

    Ingenuity - thanks again for the detailed response. For "option 1", could you confirm how you calculated the 18,000 lbf dead load? I assume it is the beam weight + slab weight, using a typical concrete density. I've included a quick sketch of the beam geometry - would the tributary area be the...
  6. toothless48

    Concrete strength for a lifting point

    Tomfh/STrctPono, thank you, I appreciate the advice. I seem to have found myself slightly out of my depth with this one. I will try to see if the building plans are available, although the building is quite old - at least part of the building was built in 1903.
  7. toothless48

    Concrete strength for a lifting point

    I did a global analysis on the overall concrete beam for simple bending. I got a tensile bending stress value of 117 psi. I have to admit my own ignorance (my career so far has mostly involved metal...), I am not sure what to do with that. Based on Ingenuity's post, a conservative assumption for...
  8. toothless48

    Concrete strength for a lifting point

    Thank you STrctPono for the input. I agree with your concern. When I did my nominal stress analysis on the bolt, I assumed a cantilever length of 2" to be conservative, which I think is about 0.75" longer than the apparent length. The steel strap is definitely an interesting idea.
  9. toothless48

    Concrete strength for a lifting point

    One more question - there are two lifting points that have been set up. The concrete condition in the first is very good, no indications. In the second, near the form ties, there is some missing material (much of which has been painted, so it has been that way for some time). This is more of a...
  10. toothless48

    Concrete strength for a lifting point

    Thank you Ingenuity for the helpful post (your diagram does represent our situation), I appreciate your time, and everyone else for your advice. This helps a lot with our assessment.
  11. toothless48

    Concrete strength for a lifting point

    Hello, I work in a small R&D lab. Our CTO had our technician set up a lifting point using a concrete beam in the ceiling of our lab (a week when I was out). I would like to validate the strength of this setup to make sure it is safe, since it was done very ad-hoc. The setup is a 3/4"-10 double...
  12. toothless48

    Water intrusion in a sealed beam

    drbrainsol, thanks for the source. Does anyone have experience with vacuum drying? I am wondering if ice formation will slow us down. I am also somewhat concerned about the ice expanding in any crevices in the beam.
  13. toothless48

    Water intrusion in a sealed beam

    Thanks for the additional input! A corrosion inhibitor sounds like a good idea, but we have very little access to the beam interior (without being destructive!), which is also divided by a baffle. I will probably seek the advice of a corrosion engineer moving forward. I wish I could share more...
  14. toothless48

    Water intrusion in a sealed beam

    Thanks all for your replies. This forum is a lifesaver, 10 heads are better than 1. For our application, a vacuum pump is going to be the best solution, being non-invasive and relatively quick. This is not a road vehicle, and we need very high reliability, so removing all of the moisture will...
  15. toothless48

    Water intrusion in a sealed beam

    Hello, I am dealing with a sealed, welded box beam (~8" x 8" x 36", 8mm wall thickness, low carbon structural steel) which acts as the backbone of a chassis frame. At some point, some small #6 tapped holes were drilled through the beam to mount a bracket. We have discovered, during a repair...
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