Piping Design Basics – Page 68

Every new code always comes with more clarifications, newly updated references related to codes & standards, additional updates to the basic allowable stresses, and newly added listed materials, So ASME B31.3 is not an exception. In the new edition of the 2012 code, there are lots of substantive changes with respect to the 2010 edition of ASME B31.3, Process Piping. This article will try to list down the changes which are important for a piping stress engineer. 1. Displacement Stress Range Allowable: The allowable displacement stress range is now limited to 414 MPa (60,000 psi) in the current 2012 edition. Normally High strength steels have higher tensile and yield strengths and so certainly higher allowable stresses. Accordingly, they also have higher allowable displacement stress ranges while calculated using the old code formula. But, these Materials have Fatigue strengths that are similar to the common steels, that is why this limit is added in the 2012 edition. 2. Stress Equation for Flexibility: The axial stress is added to the flexibility stress equation. Earlier (in 2010 edition) the same was addressed by Appendix P only. While Axial stress may not be that important in most piping systems, it can be significant for jacketed or buried piping. 3. Category D Fluid Service: The definition of Category D fluid service is revised to include a piping system with design minimum temperatures below -29 degrees Centigrade (-20 degree Fahrenheit) if the lower temperature is generated from ambient conditions. 4. Preheating: The 2012 edition changed "recommended" preheat temperatures to "required" preheat Temperatures. All metals now must be preheated to 10 degrees centigrade (50°F) or higher before welding. The above are important changes for a stress engineer. Additionally following few changes can be noted: New Appendix "Appendix N: Application of ASME B31.3 internationally" is added.Appendix H And J has been revised.Welding Qualification: Earlier Restrictions to acceptance of previously qualified welding procedures are removed. Use of Specific language about the use of standard welding procedures is added as permitted by ASME Boiler and Pressure Vessel Code, Section IX.Owner's Inspector: The qualification needs for an Owner's Inspector are broadened in the current 2012 Edition. Learn the code changes in different years:What’s new in ASME B31.3-2020? ASME B31.3 2020 vs 2018Changes in the 2018 Edition of ASME B31.3 2018 with respect to the 2016 edition.14 major changes in ASME B 31.3-2016 with respect to its earlier edition (ASME B31.3-2014)Substantive Changes to 2014 Edition of ASME B 31.3Major Stress-related differences in Between 2012 edition and 2010 edition of ASME B31.3.