Determining load capabilities of scrap metal (Safety Factors)?

[Ty Pottebaum]

I am a young engineer working for a construction company and I get a lot of requests to check the loading capabilities on random racks, jigs, etc.. These are often made of random scrap metal left over from other builds. A recent request was to see how close to the edge they could they put a 2" diameter hole in a 1" thick metal plate to hold a 3,500lb load. They wanted to leave 2" of material between the bottom of the hole and the edge of the plate. I know this is plenty of material to hold that load. In most cases I just do a simple deflection or stress calculation, such as divide the load by the cross-section of the material, given that is applicable in that scenario. This usually comes out no where near the yield stress of your basic A36 steel, 2 digit safety factors. My question is, what might your guys' process be for checking stuff like this? And what safety factor would you typically shoot for?

Thank you!

 

[Heaviside1925]

OP,
So, 2-digit safety factor, so at least 10Xs?

What does yield mean to you in terms of A36 from the mill? And how do different stresses (heat, cold work) imposed on the steel effect the material properties in terms of the original yield point? If you are using the original yield strength for your calculations, what does it mean if they place a part on the shelf and it starts to deflect?
I think you'll find if you work through this mentally, you'll answer your own question.