ASME B31.1, 2001 edition vs 2007 edition

[DM2]

In looking at the SE values for ASTM A-53, Grade A Seamless pipe it appears that the safety factor changes between the 2001 and 2007 edition. In both editions the Tensile strength and Yields are the same but the SE value, as 650°F in the 2007 edition is 13.7 ksi, and in 2001 it's 12.

The 2007 edition seems to use a safety factor of 3.5, where as the 2001 edition seems to use a safety factor of 4.0.

Am I reading this right?

Why the change from 2001 to 2007?

Regards,
Dan Marr

"Real world Knowledge isn't dropped from a parachute in the sky but rather acquired in tiny increments from a variety of sources including panic and curiosity."

 

[CodeRef]

Yes, you are reading correctly.

The 2005 Addenda to ASME B31.1 incorporated the provisions of Case 173-1 Alternative Maximum Allowable Stresses Based on a Factor of Safety of 3.5 on Tensile Strength for ASME B31.1 Construction.
This change makes B31.1 consisitent with ASME Section I and Section II Part D of the ASME Boiler and Pressure Vessel Code. This change revised the allowable stresses for almost all materials.

The ASME B&PVC Sections I and VIII incorporated these changes in the 1999 Addenda and were reflected in ASME Section II Part D.

FAQ731-376

 

[davefitz]

I think the changes also affects hydrotest pressure vis a vis multiples of design pressure. In particular for low temp components whose allowable stress are defined by UTS or yield stress, there may be a concern when a pre-2007 low temp piping system is connected to a post 2007 piping system. The test supervisor may need to ensure the hydrotest pressure does not exceed allowable for the post 2007 components.