This bulletin provides guidelines for the design of pressure vessels for operation at temperatures where the long term creep properties govern design. The ASME Boiler and Pressure Vessel Code, Section VIII, Division 1 has a long and successful service history, including elevated temperature service, however experience has shown that in service cracking problems can develop in pressure vessels at elevated temperature. The experience indicates that the cracking has occurred at locations of high local discontinuity stresses, high local thermal gradients, and weld joints. The work behind this bulletin is based on industry experience with specified practices and guidelines and screen out those design practices that have had problems from those that have been successful. The result is development of design rules, guidelines and mechanical design details that are recommended for pressure vessels operating in the creep regime. The focus is on practical design guidelines and not on complex analytical methods. The report is general in scope, however the focus is on carbon and low alloy steels. It is anticipated that many of the recommendations made will become standard practice in the industry through updates to The ASME Boiler and Pressure Vessel Code, Section VIII.