Experimental Investigation of Failure Estimation Method for Stainless Steel Pipes With a Circumferential Crack Subjected to Combined Tensile and Torsion Loads

Abstract

When a crack is detected in a stainless steel pipe during in-service inspections, the failure estimation method given in codes such as the ASME Boiler and Pressure Vessel Code Section XI or JSME Rules on Fitness-for-Service for Nuclear Power Plants can be applied to evaluate the structural integrity of the cracked pipe. In the current codes, the failure estimation method includes the bending moment and tensile force due to pressure. The torsion moment is assumed to be relatively small and is not considered. Recently, analytical investigations considering multiaxial loads including torsion were conducted in several previous studies by examining the limit load for pipes with a circumferential crack. A failure estimation method for the combined bending moment, torsion moment, and internal pressure was proposed. In this study, the failure behavior of pipes with a circumferential crack subjected to multiaxial loads including the torsion is investigated to provide experimental support for the failure estimation method. Experiments were carried out on small size stainless steel cylinders containing a circumferential surface or through-wall crack, subjected to the combined tensile load and torsion moment. Based on the experimental results, the proposed failure estimation method was confirmed to be applicable to cracked pipes subjected to combined tensile and torsion loads.

Connection Between Internal Structural Stresses of the Istand the IIndkind and Operational Reliability of the Boiler Heating Surface

“…Analysing the problems of residual life prediction and life extension of the heating surface, it may be noted that in the listing of hazardous operational factors within the boiler and reactor engineering processes to improve the quality of designed models, to provide recommendations on the choice of materials, safe operating temperatures, in diagnosis and prevention of cracking and brittle fractures the role of internal structural stresses kinds I and II is not evaluated, clearly manifesting themselves in the process of structural and physical degradation of structural materials and determining in this respect individual physical capabilities of the metal [1].…”