In addition to the many clarifications, updated references to codes and standards, updates to basic allowable stresses, and added listed materials, there are several substantive changes to the 2012 Edition of ASME B31.3, Process Piping. These changes are:
Category D Fluid Service
The definition was revised to include piping with design minimum temperatures below -29⁰C (-20⁰F) if the cause of the lower temperature is from ambient conditions.
Allowable Displacement Stress Range
The allowable displacement stress range was limited to 60,000 psi (414 MPa) in the 2012 edition. High strength steels have higher yield and tensile strengths and thus higher allowable stresses. Therefore, they also have higher calculated allowable displacement stress ranges when calculated using the old formula. However, these materials have fatigue strengths similar to the more common steels, which is why the limit was added.
Flexibility Stress Equation
The axial stress was added to the flexibility stress equation. While axial stress in not important in most piping systems, it can be important for piping that is jacketed or buried. The 2010 edition required that it be considered, but it was not in the equation.
Restrictions to acceptance of previously qualified welding procedures were removed. Specific language about use of standard welding procedures as permitted by ASME BPV Code, Section IX was added.
The 2012 edition changed “recommended” preheat temperatures to “required” preheat temperatures. All metals must now be preheated to 10⁰C (50⁰F) or higher before welding.
The qualification requirements for an Owner’s Inspector were broadened in the 2012 Edition.
MPa Stress Table
The MPa allowable stress table first appears in the print version in the 2012 edition. This table is still just for information. The psi allowable stress values are the requirement.
[readon2 url=”index.php?option=com_rsform&view=rsform&formId=4&Itemid=620″]Click to Request Info[/readon2]