Creep Life Design Criterion and Its Applications to Pressure Vessel Codes

Pressure vessels equipment is used in the oil, chemical, nuclear power plant and many other industries. Life prediction of such components subjected to high temperature is very important to avoid the catastrophic consequences of failure. The designer often works to the requirements of a standard or code of practice. In mentioning codes and standards, one should also mention that in many nations there is a national organization which develops such standards. In France, there is the RCC-MR practice code for creep design; the R5 from the British Energy, and many other methods proposed by the European Creep collaborative Committee (ECCC) and the National Institute of Material Science (NIMS) in Japan. However, the major shortcomings of the abovementioned standards, they are not practical to use or/and too conservative which involves many other considerations such as economics, safety and manufacturing problems. This paper describes a relatively pragmatic and accurate paradigm for predicting the lives of such components. The application of the proposed paradigm to an internally pressurized vessel shows that the elastic-plastic-creep life of the component can be predicted with an error of less than 10 %.