HIGH TEMPERATURE BOLTING SYSTEM

摘要

A high temperature bolting system for clamping steam turbine housings and similar high temperature parts together while operating at a temperature of 800 .degree.F to 1200 .degree.F. An elongated fastener shan k and housing material have similar coefficient of thermal expansion. The shank has a tensile strength several times greater than the housing to maintain a clamping force during thermal excursions. The diameter of the shank is reduced due to the large creep strength difference between t he elongated fastener shank and the clamped parts. The reduced shank diameter allows an increase in the clamping load by providing an increased surface area in the clamped part. A stress generating flange is provided with jackbolts to establish the clamping load at room temperature. A threaded sleeve is interposed between the threads at the end of the shank and the threads of the housing so that the housing threads have a sufficiently large area for withstanding the clamping load. A truncated conical internal wall in the shank in combination with a differential thread pitch in an embodiment provides higher resistance to the clamping force. A flanged support ring is mounted a t a bolt hole in the flange to support a load bearing area when retrofitting existing housings.