Improvements to ASME Section VIII, Division 1 Code rules over the last 40-50 years, successful experience with vessels designed to the Code rules, improved materials and fabrication practices, more sophisticated design rules and toughness requirements have prompted a further review of the Section VIII, Division 1 requirements to see if there is a justification for a reduction in the present Code design margins from a factor of 4 to 3.5 on the ultimate tensile strength at temperatures below the creep range.This report discusses the successful experience with vessels designed to Section VIII, Division 1 rules, the failure modes considered in the Code rules and margins on design, improvements in the Code rules since the last reduction of the design margin, the Code paragraphs affected by changes in the design margins, areas which need a further review, and recommended additional work as a follow-up to this study to further justify the lower design margin.