Dead-Weight Stresses in Piping Systems and Their Inclusion in Thermal Stress Analyses

Abstract

A method is given of accurately analysing the dead-weight stresses in piping systems. Both the uniformly distributed weight of the pipe and its insulation, and point loads such as valves are considered. The effects of constant-support spring hangers or counterweights are also included in the analysis.

The paper is based on the Meyer-Hovgaard and grapho-analytical systems of pipe stress analysis which in their present form deal solely with thermal expansions. These methods have been extended to deal with the dead-weight of both straight and curved pipe, and the effects of the flexibility and stress intensification factors for bent pipe may be included.

For large-bore, low-temperature pipes, the dead-weight analysis may be carried out on its own. For high-temperature pipes the dead-weight analysis may be included as an integral part of the thermal analysis for the pipe, using the same flexibility coefficients as for a normal thermal analysis.

Tables of dead-weight constants have been derived, which for a dead-weight analysis replace the normal thermal expansion constants. An example is given of a three-dimensional 24-in. pipe at 950°F subjected to thermal expansions and its own dead-weight. Suitable support for the pipe is considered in the analysis.