Effect of Wall Thickness on Stress-Rupture Life of Tubular Specimens

Abstract

Stress-rupture data obtained from tubular specimens stressed with internal pressure are compared with data from standard tension-bar specimens from the same heats of material. Agreement between the data of the two types of specimens is poor for thick-wall tubes when the hoop stress in the tube wall is calculated on an average stress basis. Better agreement is obtained with thin-wall tubes. These results show that any design formula that neglects the variation of stress through the thickness of a tube wall is unsatisfactory for thicker tubes. A dimensionless parameter method is presented which provides satisfactory correlation of the data for three materials, four test temperatures, and a wide range of wall thickness. Several areas in which additional research would be of value are discussed.