Certifying non-standard materials?

[AXNRXN]

Hi All,

I'm working on a quote for a client of mine that wants an engineering certification for a lightweight hanging frame. This frame is constructed out of EMT: the electrical conduit that you run wires through. There is no standard for EMT material properties as its typically not used structurally. However, I sent out a few emails and did received UTS and yield values for a manufacturer's EMT conduit.

What are your thoughts about doing certifications for projects using non-standardized materials? While this project will likely have a Factor of Safety in excess of 10, I still have a uneasy feeling certifying a frame using materials that are not subject to any structural standard. Note that there is no formal code that these frames are governed by that would specify minimum material strength.

Thanks for any insight,
--> Karl

 

[TVP]

What exactly is a "lightweight hanging frame"? Is it subject to dynamic loads rather than just static? What is the expected lifetime of this frame? If it is just a static load, and you can actually test an example (build 2, test 1), then it may be possible to have confidence in the structure together with a design margin of ~ 10.

 

[AXNRXN]

It's a rectangular frame wrapped in graphics to make a sign. Pretty Simple. No dynamic loads and hardly any additional weight.

Testing is a possibility. I could have them load the unit to a suitable FOS and record the results.

I'm not too worried about it actually being strong enough structurally. I'm sure it will be. But, without any given strength data, I suppose physical testing is the only way to confirm that it is sound.

 

[Duwe6]

It would be like a non-specified shape of pressure vessel. "Scientifically" destroy a couple of them, using measured weights and forces. Your Max Allowable Load is now 1/4th or 1/5th of the failure load [you pick the safety factor].

 

[metengr]

Lightweight hanging frame - can failure of this frame result in harm to property or people???

What are your thoughts about doing certifications for projects using non-standardized materials? While this project will likely have a Factor of Safety in excess of 10, I still have a uneasy feeling certifying a frame using materials that are not subject to any structural standard. Note that there is no formal code that these frames are governed by that would specify minimum material strength.

Certification without reference to an ISO or ANSI standard means absolutely nothing. If you are having a Professional Engineer review and stamp a drawing that can be used to build this frame, so be it. The risk I envision is that you can have material with such variability in properties that as a PE may not want to put their reputation on the line. You should have some material standard. There are materials that can be used for this frame that are supplied with some known and accepted reference standard.