Waterhammer analysis (herein referred to as Hydraulic Transient Analysis or simply “HTA”) becomes more complicated when transient cavitation occurs (also known as liquid column separation). While standard HTA transient cavitation models used with analysis based on the Method of Characteristics show good correlation when compared to known test/field data, the great majority of test/field data are for simple systems experiencing a single transient. Transient cavitation in more complicated systems or from two or more independently initiated transients have not been validated against data.
Part 1 of this paper describes the various safety factors already provided by ASME B31.3 for pressure containment, provides criteria for accepting the results of HTA calculations that show the presence of transient cavitation, and makes recommendations where the user should include additional safety factors based on the transient cavitation results.
Situations are discussed where waterhammer abatement is recommended to reduce hydraulic transient pressures and forces, and for increasing confidence in HTA results in specific cases. The result is a proposed comprehensive and pragmatic guideline which practicing engineers can use to perform waterhammer analysis and apply pressure predictions to pipe stress analysis.
