Old ASME Allowable Stress Criteria 1

[zakk]

Does anyone have a copy of ASME Section II Part D prior to the change in the Allowable Stress Safety Factor from 4.0 to 3.5?

S(Allowable) = S(Tensile)/4.0

I need to know, from Table 1-100 the safety factor used for establishing the allowable stress using YIELD STRENGTH.

In 2007E, S(Allowable) = 2/3*S(Yield). What was the factor prior to it being changed to "2/3"?

I don't have a copy of the old Code available.

Thanks in advance.

 

[jte]

zakk-

Pre- A99 the criteria were basically (Tensile at temp)/4, (2/3)*(yield at temp), or time-dependent.

A99 changed the tensile factor but did not change the others. Some materials did not get the full benefit even at moderate temperatures if they changed from being governed by tensile to being governed by the yield criteria. As an example, SA516-70 at 600°F used to be governed by the tensile criteria (70ksi/4) but is now governed by the yield criteria (29.1ksi*2/3). This results in about a 11% increase in allowable stress vs the 14% which would be expected if tensile still governed.

jt

 

[zakk]

Thanks, JT. You get a star!