Creep Rupture Testing of Tubular Model Components
Materials data for use in design and remanent life estimates of engineering components operating in a creep regime, are invariably derived from isothermal, constant load creep and rupture tests on homogeneous specimens of simple design. In service, however, components generally operate under conditions of multiaxial stress and may be subject to systematic and random variations of temperature and load. Furthermore, the components may be of complex geometry and contain compositional and microstructural inhomogeneities introduced by welding. In theory, it should be possible to predict component life analytically using stress analysis together with materials data and an appropriate damage model. However, in practice, limitations of finite-element stress analysis in the creep range and current uncertainties in multiaxial materials data, preclude rigorous assessments for all but the more simple situations, such as a steam pipe operating under essentially constant conditions of pressure and temperature. For these reasons, laboratory creep testing of components is often desirable to underwrite their integrity in service. Currently, there are only 10 test points in the UK, at the CEGB Marchwood Engineering Laboratories (MEL), where large power plant components, such as steam pipes and headers, can be tested under conditions representative of those in service.
KeywordsWeld Metal Heat Affected Zone Hoop Stress Creep Strength Rupture Life
Unable to display preview. Download preview PDF.
- Browne, R. J. (1985) Creep strain accumulation in internally pressurised tubes and preliminary evaluation of a strain based life assessment model. CEGB Note SER/SSD/85/0014/N.Google Scholar
- Browne, R. J., Cane, B. J., Parker, J. D. and Walters, D. J. (1981) Creep failure analysis of butt welded tubes. Int. Conf. on Creep and Fracture of Eng. Mails, Pineridge Press Ltd, Swansea, pp. 645–59.Google Scholar
- Browne, R. J., Lonsdale, D. and Flewitt, P. E. J. (1982) Multiaxial stress rupture testing and compendium of data for creep resisting steels. Trans. AS ME, J. Eng. Mails and Tech., 104 (4).Google Scholar
- Browne, R. J., Welham, M. C. and Elder, W. J. (1982) Internal-pressure stress-rupture tests on butt welded tubes. CEGB Note SER/SSD/82/0002/N.Google Scholar
- Cane, B. J. and Browne, R. J. (1979) Creep rupture criteria in pressurised tubes and pipes. CEGB Note RD/L/N177/78.Google Scholar
- Coleman, M. C. and Parker, J. D. (1985) The deformation and fracture of thick section 1/4Cr-1/4Mo-1/2V to mild steel pipe weldments at elevated temperature. To be published.Google Scholar
- Elder, W. J. (1971) Rupture testing under complex stress extension of tube testing facility. CEGB Report SSD/SE/RR/16/71.Google Scholar
- Finnie, I. and Heller, A. (1959) Creep of Engineering Materials, London, McGraw-Hill.Google Scholar
- Heather, C. W., Browne, R. J. and dér, T. J. (1980) Application of CERL-Planer high temperature strain gauges for the measurement of hoop strains in tubular components. CEGB Note SE/SSD/RN/80/066.Google Scholar
- Noltingk, B. E., McLachlan, D. F. A., Owen, C. K. V. and O’Neill, P. C. (1972) High stability capacitance strain gauges for use at extreme temperatures. Proc. Inst. Elect. Engrs, 119 (7).Google Scholar
- Rowley, T. and Coleman, M. C. (1973) A collaborative programme of the correlation of test data for the design of welded steam pipes. CEGB Note R/M/N710.Google Scholar
- Walters, D. J. (1976) The stress analysis of cylindrical butt-welds under creep conditions. CEGB Note RD/B/N3716.Google Scholar