Experimental apparatus for thermal shock fatigue investigations

An experimental rig developed for investigating crack growth in pressure ve ssels and piping equipment is described. The rig allows full scale modeling of cyclic thermal shock conditions that occur in operating thermal power s tation pressure equipment. It has the ability to apply a primary steady sta te mechanical load and to control the quenching environment allowing the st udy of the effect of welds and stress concentrators under conditions that s imulate operational loadings. These results can be used for lifetime assess ment. Preliminary results from the test rig analysing the effect of primary load on crack initiation and growth are presented and discussed briefly. A compa rison with prediction methods from the ASME Boiler and Pressure Vessel Code is made. It is concluded that the primary load has little or no effect on crack initiation times, however it significantly affects the crack growth r ate. (C) 2000 Elsevier Science Ltd. All rights reserved.