Investigation into the Benefits of Using Asme Bpvc Section Viii Division 2 in Lieu of Division 1 for Pressure Vessel Design

ASME Boiler and Pressure Vessel Code Section VIII Division 1 [1] is one of the most commonly used pressure vessel codes in the world. The Division 1 rules were originally written before the age of computers; they were intended to be solved by simple hand calculations. This simplification led to rules with a high safety margin and a conservative technical basis. In 2007, ASME published a completely rewritten edition of ASME BPVC Section VIII Division 2 [2], intended to lower the safety margin by introducing more complex, technically accurate pressure vessel design rules, and make the Code more cost-competitive in an international market. The Division 2 Code saves the user money on materials with the use of higher allowable stresses and more accurate design formulas. However, in order to justify the increase in allowable stress, Division 2 mandates additional NDE and a Professional Engineer’s stamp, which raise the vessel price. At a certain thickness, the material savings outweigh the additional cost, and Division 2 becomes cost-effective. Six years after publication of the new Division 2, the industry has yet to identify the thickness at which the transition from Division 1 to Division 2 becomes cost-competitive. Division 2 is still most commonly used only for very high pressure, high thickness applications. This investigation compares Division 2 to Division 1 to determine a reasonable set of design conditions by which Division 2 will yield a more cost-effective pressure vessel, even on some lower pressure applications. NOMENCLATURE = weld consumable cross section area ASME = American Society of Mechanical Engineers BPVC = Boiler and Pressure Vessel Code = corrosion allowance