Question About Steel Type

[gskinner]

Greetings:

I am not sure if this is the correct forum for this question; so my appologies, if it is not. I am working on a reverse engineered drawing of a weld fixture that contains a piece of hollow square steel, that measures 2 1/2" square, and has a 7/16" wall. Every structural steel chart I have seen, so far, shows no wall thickness greater than 1/4", for 2 1/2" square tubing. Can anyone please tell me what to indentify this material as?

Thank you very much.

Sincerely,
Gary Skinner

 

[racookpe1978]

Any four pieces of (assmued) mild steel plate can be assembled by welding into a rectangular tube of the dimensions stated. Verify the part measurements and configuration, and look for indications of welds on the corners" Two angles? Four plates? Could be several ways of putting it together.

You will have to go back to fundamentals to calculate the wall stresses and "S" values the are created by the weldment. If the shape isn't in the standard tables, you can still calculate properties. Be sure you determine what material and strength you have as well.

 

[JStephen]

If it's normal structural tubing, it would have rounded corners. My AISC "Hollow Structural Sections" book shows up to 5/16" wall thickness in that size.

When dealing with round sections, you have standard pipe sizes, but also have some mechanical tubing sizes that are different- perhaps there is similar material available in square. For example, members of a truck frame wouldn't necessarily be standard structural members.

 

[gskinner]

Thank you both, for your responses. With appologies; I should have made it clearer, that the piece in question is a single piece of material that, like square tubing, appears to have been formed into a square profile, from hollow round stock; so it does have rounded corners, as you mentioned, JStephen. I would call it square tubing, but I'm not sure that, because of its wall thickness, its not considered something other than tubing.

-Gary

 

[bdSE]

If your measurement is coming from a drawing (that's what it sounds like in your problem statement), and is not a physical measurement of the existing piece... you need to consider that the drawing could have a typo.

HSS 2 1/2 x 2 1/2 x 5/16 is available according to the current AISC Steel Manual. It is possible that a typo could have happened here.

If, on the other hand, you are taking your own measurements, make certain that you are using accurate calipers (measure something known to verify the tool is working properly). Next, take several wall thickness measurements to ensure that you didn't just pick a thick wall. Manufacturing tolerances can not account for a jump from 5/16 to 7/16.

I checked a few metric sizing charts and saw nothing in that thickness range, barely even half that thick.

It could be a custom piece, or it could be a bad measurement. Hope that helps you go farther in the right direction. Let me know if I made some bad assumptions and I'll keep thinking about this with you.

What are you shooting to reverse engineer? Make another one of your own design? Figure out the strength properties of the parts? You could simply make some conservative estimates (such as 5/16 and 36ksi steel for starters as a suggestion).

 

[racookpe1978]

Aluminum can be formed into "square cornered" tubing - but I've never seen any Al tubing 7/16 thick.

Steel that thick with "squared corners? Never seen, but won't say somebody didn't do it.

Don't duplicate an earlier bad design!

Just because "he always did it that way" or "she used to do it that way" would mean we would still use hand forges, steam locomotives, and horses and muscles rather than diesel-powered combines.

 

[gskinner]

Again, I thank each of you for responding. I am not getting my dimensions from a drawing, but from measuring the actual material. I am reverse engineering the drawing. The material in question is definitly some kind of purchased hollow square structural steel; not anything that has been made by altering something else. I would have prefered not to have to admit my ignorance (although I am obviously not alone), but it looks as though I may have to ask my customer what the suff is, or from whom they purchase it; so I can ask them.

Thanks again.

Sincerely,
Gary Skinner