Integrating Isolation Valve Specifications Into Supercritical Power Plant Piping Design Specifications

Clean and cost effective super critical power plants (SCPP) require “whistle clean” conditions, low emissions, low noise, higher velocities and flow rates. A majority of the specification packages for valves are developed by experienced piping engineers, assigned to EPCs and the valve section comprises a relatively small element where references to industrial standards like ASME B16.34 or ANSI B31.1 are made for design and stress parameters. The specific valve data sheets then provide some more information as to operating and boundary conditions for the specific valves. With the increasing prevalence of SCPP requirements, the current specifications made available by EPCs, make it somewhat enigmatic for valve designers and manufacturers to address the concerns of the power plant designers and engineers. This is in terms of valve bores, pressure drops, velocities, thermal fatigue, lowered valve weights and acceptable sound levels that are intrinsic to valve design, sizing and optimization. This paper presents some specific examples where flows, velocities, pipe ID and valve bore are compared to enable a better integration of piping characteristics in relationship to safe valve design, without unnecessarily over-specifying. In addition, suggestions have been made for an understanding of the relatively newer piping and valve materials for high temperature, high pressure applications, where alternative design methods would enable lower costs and greater resilience to thermal binding and fatigue.