This article discusses how a facility would need to get one of its coded pressure vessels repaired, altered, or re-rated. The article will cover pertinent code and jurisdiction requirements and the differences among the American Society of Mechanical Engineers (ASME) Code, the National Board Inspection Code (NBC), and American Petroleum Institute (API) requirements, as well as discuss the following: design of repairs; planning and approval; responsible organization; materials; replacement parts; welding; postweld heat treatment (PWHT); inspections and hydro test procedures; and documentation and nameplates.
A pressure vessel inspection program will, from time to time, reveal that some form of deterioration is occurring in a vessel. Analysis of the deterioration may indicate that the vessel must either be repaired under the original design conditions or that the vessel must be rerated for less severe design conditions. Rerating for new design conditions may also be necessary because of changes in operating requirements.