Allowable stress values changes in editions of ASME B31.3
Allowable stress values changes in editions of ASME B31.3
(OP)
Hello everyone,
Have the allowable stress values in ASME B31.3 changed along with the release of the different editions of this code?
Can any of you route or guide me towards a historical reference or table where I can see the changes of the allowable stress values in time with the release of new versions?
This might be a silly question but I have also noted that these values in B31.3 differ from ASME Sec II-D. What is the reason for that? aren't they the same materials?
Regards!
Have the allowable stress values in ASME B31.3 changed along with the release of the different editions of this code?
Can any of you route or guide me towards a historical reference or table where I can see the changes of the allowable stress values in time with the release of new versions?
This might be a silly question but I have also noted that these values in B31.3 differ from ASME Sec II-D. What is the reason for that? aren't they the same materials?
Regards!





RE: Allowable stress values changes in editions of ASME B31.3
Yes they are the same materials. II-D uses a different factor over yield and tensile compared to B31.3. See B31.3 302.3.2 and II-D Mandatory APpendix 1.
Also see http://www.eng-tips.com/viewthread.cfm?qid=372382
RE: Allowable stress values changes in editions of ASME B31.3
The allowable stresses in Annex A of ASME B31.3 are based on the minimum of yield/1.5 and UTS/3. If you're looking at Chapter IX then the allowable stresses in Annex K are yield/1.5.
There are a number of allowable stress tables in ASME II-D and which one you use depends on what your application is. Some of the Mandatory Appendices at the back explain how these are derived. As a cursory summary, for ASME VIII-1 vessels the allowable stress is the minimum of yield/1.5 and UTS/3.5, and for ASME VIII-2 vessels the allowable stress is the minimum of yield/1.5 and UTS/2.4.
In general I do not believe the factors have changed for process piping like they have done for the B&PV codes (i.e. ASME VIII-1 pre 99a which had a UTS factor of 4), although I seem to recall there was a change to some of the higher strength materials around the 2012 edition? If you're doing an assessment of older equipment, as a first pass, it's best to use the allowable stress from the code edition to which it was designed to.
RE: Allowable stress values changes in editions of ASME B31.3
RE: Allowable stress values changes in editions of ASME B31.3
It seems that this will be a research job... find older versions of B31.3 and build a sort of table with the changes over time of the stress values.
If I ever manage to do that I will share it with you guys.
Regards!
Cesar