Dynamic Pipe Stresses During Water Hammer: V — Applications

Abstract

Theoretical equations to describe dynamic stresses during water hammer were developed in the first four parts of this series of papers, and this fifth paper applies those equations to analyze piping failures in a nuclear waste facility. The pipe failures were shown to be coincident to valve closures and pump shut downs, which caused fluid transients in the system. Magnitudes of the pressure increases during the transients were calculated and implemented in dynamic stress analyses for the piping. The maximum pipe stresses were then compared to the fatigue stresses of the pipes, and the failure mechanisms were thus established. By slowly closing valves, the effects of the fluid transient can be nearly eliminated. Using the closed from equations, the minimum time of valve closure may be calculated to prevent recurrent pipe failures. This application of the original closed form solutions provides further insight into the use and validity of the new dynamic stress equations.