A study on pipe bends, an analysis of the smooth pipe bend with flanged end constraints under out-of-plane bending and the development of experimental techniques in the creep of pipe bends

In the design of piping systems the importance of the pipe bend is well established. Recent publications have been increasingly concerned with the effect of end constraints on the behaviour of smooth pipe bends. This has been aimed almost exclusively at in-plane bending, there being no serious attempts at the solution to out-of-plane bending. In PART (1) of this thesis a theoretical solution is presented for the out-of-plane bending of linear elastic curved pipes with rigid flanges. The analysis employs the theorem of minimum total potential energy with suitable kinematically admissable displacements in the form of fourier series. Integration and minimisation is performed numerically. Results are given for a wide range of practical bend geometries. A comparison with previous theoretical predictions highlights the inadequacy of these earlier solutions. The present results are shown to be in favourable agreement with results from tests conducted by the author and more recent results using a different solution procedure. Work in the creep of pipe bends necessitates a substantial amount of experimental work and expertise. Most publications dealing with the creep of pipe bends under bending loads fail to present much information on this aspect. In PART (2) of this thesis a general description is given of an experimental creep programme on pipe bends. The measurement of strain at elevated temperature was accomplished using the CERL-PLANER capacitance strain gauge. It is shown that the application of this gauge to pipe bends requires particular techniques if meaningful results are to be obtained. The results of development work arising from other problems encountered during the test programme are also presented. These include the measurement of displacement and distortion at elevated temperature and the provision of an efficient and novel heating system.In the design of piping systems the importance of the pipe bend is well established. Recent publications have been increasingly concerned with the effect of end constraints on the behaviour of smooth pipe bends. This has been aimed almost exclusively at in-plane bending, there being no serious attempts at the solution to out-of-plane bending. In PART (1) of this thesis a theoretical solution is presented for the out-of-plane bending of linear elastic curved pipes with rigid flanges. The analysis employs the theorem of minimum total potential energy with suitable kinematically admissable displacements in the form of fourier series. Integration and minimisation is performed numerically. Results are given for a wide range of practical bend geometries. A comparison with previous theoretical predictions highlights the inadequacy of these earlier solutions. The present results are shown to be in favourable agreement with results from tests conducted by the author and more recent results using a different solution procedure. Work in the creep of pipe bends necessitates a substantial amount of experimental work and expertise. Most publications dealing with the creep of pipe bends under bending loads fail to present much information on this aspect. In PART (2) of this thesis a general description is given of an experimental creep programme on pipe bends. The measurement of strain at elevated temperature was accomplished using the CERL-PLANER capacitance strain gauge. It is shown that the application of this gauge to pipe bends requires particular techniques if meaningful results are to be obtained. The results of development work arising from other problems encountered during the test programme are also presented. These include the measurement of displacement and distortion at elevated temperature and the provision of an efficient and novel heating system