An important element in evolving Section III of the ASME Code is the re-examination of Code rules to identify the potential for efficiencies. The present paper looks at the rules for reinforcement of openings. The present Code rules require the area of material removed to create the opening (up to the design thickness) to be added around the opening with certain limits on the distance from the opening. Past studies have suggested that the present rules may add more material than needed to maintain the strength of the vessel in some cases.
The optimum amount of reinforcement is therefore postulated to be determined by the criterion that the limit pressure should not be reduced excessively relative to the limit pressure of the vessel in the absence of the opening.
Limit analysis is performed to derive possible rules on the amount and distribution of around an opening. Options for alternative rules for reinforcement of openings, and restrictions on the present Code rules, are proposed.