Max Allowable Stress Value

[Kelvigal1000]

Hi,

I am trying to find the max. allowable stress value & Tensile Strength Su, for A1011 Gr 50 material for performing stress calculations. I tried finding it in Section II Part D book, but with no success.

Appreciate any help.


Thanks

 

[TGS4]

The yield and ultimate stresses at room temperature are provided in the material specification (as would be found in Section II, Part A). Otherwise, the material is not found in Tables 1A, 2A, or 5A, indicating that is it not permitted for use in construction of a Section I, III, VIII or XII construction - and hence no allowable stresses are provided.

To which Boiler or Pressure Vessel Code are you fabricating using this material?

 

[Kelvigal1000]

Hi,

Thanks for the reply.

It is for Specification DOT 400 Series cargo tanks.

A1011 has been listed as authorized for construction of DOT 400 Series cargo tanks.

 

[JStephen]

In general, the allowable stress from a code is for use in that code and is not a fixed value for all applications. For example, our most common material is A36, and it has one allowable stress in ASME, a different stress in API-650, a different stress in AISC-ASD, etc.

With that in mind, I would assume that if a code or standard allows the use of a material and doesn't specify an allowable stress or means or source of obtaining one, that it is the engineer's judgment to use an appropriate value.

You might note that the basic safety factor in the current ASME is 3.5, and for A36, tensile strength is 58,000 psi, allowable stress at ambient temperature is 16,600 psi, and 58,000/3.5 = 16,570 psi, and a similar approach might put you in the ballpark with your material. There may be various reasons to rate a material lower than this (low toughness, for example), and some of the other standards are less conservative than this. I would think in a vehicle application, fatigue might be a limiting factor also.