22 Section VIII: Division 2—Alternative Rules

Chapter 22, authored by Kamran Mokhtarian, discusses Section VIII, Division 2 (Alternative Rules). This chapter summarizes the more significant requirements of Section VIII, Division 2 and gives a commentary on these requirements. When appropriate, comparisons are made with Section VIII, Division 1. The comments on and interpretations of the rules are strictly the opinions of the author; they are not to be considered official ASME Code Committee interpretations. The Code requirements have been simplified and may not reflect all details of the rules; the applicable Code Edition must be consulted for actual applications. This chapter is based on the 2001 Edition of the Code with Addenda up to 2003, and some pertinent Code Cases for Division 2 are included. Unlike Division 1, which has evolved over the past eight decades and lacks a highly organized delineation of the various types of requirements, Division 2 was developed with a definite organization considered.

Kamran traces the history of Division 2, compares Division 1 and Division 2, and addresses all of the salient Code parts and cross-references the overlap among various parts. The commentary includes general and design requirements; design for internal pressure; design of shells, flat heads, and bolted connections; attachments and supports; access and inspection openings; reinforcement of openings; nozzle attachment details; pressure-relief devices; material and toughness requirements; fatigue analysis and exemption rules; welded joints; fabrication requirements and tolerances; heat treatment; inspection and radiography; testing requirements; marking, stamping, and data reports; Mandatory and Nonmandatory Appendices; and pertinent references. Kamran believes that the tendency to avoid using Division 2 is attributed to the relative complexity of its rules and inadequate realization of its overall cost savings. Unless very complex loadings are specified, the design and analysis rules of Division 2 are not difficult to apply, and the use of Division 2 offers savings for many vessels that are routinely fabricated to Division 1.