"Scope and Applicability of the Item This Item provides both graphical and computerised methods that may be used to estimate the magnitude of surge pressures in steam lines following a change in the flow rate. The graphical method for the estimation of pressure change and time-dependent piping forces following rapid closure of a turbine stop valve is applicable to one-line systems such as that shown in Sketch 2.1. The method used to generate the data is outlined in Appendix A. In deriving the graphical data@ it was assumed that the fluid obeys the perfect gas law@ which limits the applicability to superheated steam and other gases that follow this law. The data are therefore not applicable to saturated steam and wet vapours. In this Item@ the term ""steam"" refers to superheated steam and other appropriate gases. In the one-pipe system shown in Sketch 2.1@ superheated steam flows from the steam generator to the turbine@ which is protected by a stop valve on the upstream side. It is assumed that the pipe system between the steam generator and the stop valve is of constant cross section@ without branches@ and that all reflections of pressure waves from pipe bends@ etc. are negligible. It is further assumed that all pressure and density changes follow adiabatic processes@ and that all friction effects can be neglected. In addition@ all wave steepening effects (see Section 3.3) are neglected. The graphical data allow investigation of the effect on the pressure changes of varying the stop valve closure characteristics. Further guidance on these matters is given in Section 4. The computer program introduced in Appendix B allows similar systems to be investigated without recourse to all of the simplifying assumptions that are necessary for the graphical presentation. The full scope of the program is described in Appendix B."
ESDU 86015-1986 history
1986ESDU 86015-1986 FLUID TRANSIENTS IN PIPES Estimation of Maximum Pressures and Forces in Steam Lines