Allowables stresss for internal support grating and support beams

[jtseng123]

Dear all,

Can you use Div 1 allowable stress or Div 2 allowable stress as the "allowable bending stress" to design internal support grating and removable support beams for both CS and SS parts? I normally use 2/3 of the yield as the allowable bending stress regardless it is CS or SS.

 

[Duwe6]

Being a Non-Pressure Boundary item, you can use anything you like for "allowable stress". It just has to meet engineering judgment.

 

[JStephen]

If I remember right, the capacities in the grating catalogs are based on 20,000 psi.

 

[racookpe1978]

What is the temperature and environment in there? Is your metal going to corrode out (lose thickness or integrity) before you can replace it?

 

[Spoonful]

my 2 cents,

You may , but you may end up over conservative, I would consult AISC specification, ranging from 0.6Fy, 0.66Fy or 0.75Fy depending on geometry.

 

[jtseng123]

All,
It is for ethylene plant, can be either carbon steel or stainless steel grating, and temperature is 540F. Many times, grating will be special design. I have a supplier want to use allowable stress in Div. 2 or Div .1. But I oppose to it, as I see 2/3 of the yield is widely used. Is it too conservative ?