Behaviour of steam generator bolted flange joints at elevated temperatures

摘要

Manholes with flanged joints are provided in the sodium heated once through straight tube steam generators of Prototype Fast Breeder Reactor (PFBR). The material of construction of steam generator is modified 9Cr 1 Mo grade steel with studs made of 1 Cr 0.5 Mo steel. During the commissioning of model steam generator, the flanged joint lost its leak tightness at elevated temperature due to differential thermal expansion between flange and stud. A design modification incorporating sleeves of higher thermal expansion coefficient is discussed in this paper.