Circumferential Creep Strain of Cylinders Subjected to Internal Pressure: A Comparison of the Theories of Johnson and Bailey

When considering the creep of cylinders subjected to internal pressure, the theory of Johnson et al. takes into account progressive changes of radial, circumferential and axial stress at any point in the wall thickness. This approach differs from that put forward by Bailey, who assumed that these stresses remained constant with time. The present paper summarizes an examination of both theories, with particular reference to outside and bore diameters, and presents simple equations which enable circumferential strain to be calculated without using the complex graphical integration procedure suggested by Johnson. Furthermore, it is demonstrated that these equations are mathematically identical with those derived by Bailey.