On the influence of dimensional inaccuracies on the stress calculation of piping systems

Abstract

In general, calculations on the propagation of errors in the stress analysis of statically indeterminate framed structures (e.g. piping systems) lead to the following problem: there are given ranges of variation of certain physical parameters (dimensions, loads, material characteristics) from which the coefficients and constants of a system of linear equations are calculated. The stress in the system are a function of the solution vector of this system of linear equations. For the critical stresses the range of variations are required which are caused by the variations of the physical parameters. This paper is concerned with demonstrating the difference which exists between this problem and the problem encountered when the coefficients and constants — independently — are subject to some variation, for instance, as a result of inaccuracies in the calculation. Furthermore, a method is indicated which facilitates the approximate calculation of the maximum variation of a critical stress even in cases where a relatively great number of parameters is subject to variations independent of each other.