Design of steam-turbine casing flanges: A two-dimensional photoelastic study

Abstract

Photoelastic tests have been made on two-dimensional models of steam-turbine flanges for various combinations of the flange parameters depth, width, and bolt position. Design curves have been produced which show the relation between these flange parameters and the ratio of bolt force to pressure force necessary to produce a compressive stress at the inner edge of the flange equal to the internal pressure, this being the criterion adopted to ensure steam-tightness. Comparisons have been made between the experimentally determined stress distributions and distributions calculated by various methods. Of computer-aided methods, the English Electric Kidsgrove structural-analysis programme gave the best correspondence to the experimental results with a relatively simple idealization of the problem. When the depth of a flange exceeds the width and the bolt load acts within the inner half, the stress distribution is reliably predicted if the flange is assumed to behave as an eccentrically loaded column.