Common use of Control Valves Clause in Contracts

Control Valves. EPC - Exhibit B -------------------- TENASKA GEORGIA GENERATION PROJECT Page 127 of 132 -------------------------------------------------------------------------------- The entire operating load range of the plant shall be fully considered when developing the control valve specification sheets. Control valve body sizes shall not be more than one pipe size smaller than the nominal pipeline size up to eight (8) inches. For nominal line sizes greater than eight (8) inches, control valve body sizes shall not be more than 2 pipe sizes smaller than the nominal pipeline size. Valve travel shall not exceed 80 percent at the maximum operating condition. Valve noise (excluding steam conditioning valves) shall not exceed 95 dBA @ three (3) feet. Control valve sizing and detailed requirements shall be the responsibility of the Contractor. ISA Format Data Sheets shall be used to specify the valves. Control valves shall conform to the requirements of ANSI B31.1, Code for Power Piping and be suitable for use under the specific operating conditions. Handwheels shall be provided on all air-operated valves. The control valve body shall be no more than two nominal sizes smaller than the line in which the valve is installed. Body fluid velocities shall be limited to 40 fps as liquid and 0.3 mach as vapor or gas. Trim sizes may be reduced to 0.4 factor trim minimum when pipe size or velocities are limiting. Valves shall be capable of passing 125 percent of the normal capacity. If the maximum capacity is listed, the valve shall be capable of passing 105 percent of that figure. Globe and angle type valves will have cage, top and bottom, or top guiding (no skirt guiding). Bonnets shall be flanged or of integral construction. The packing gland shall be the bolted type. Under the normal range of operating conditions the sound level at any point 3 ft radially from the surface of the downstream pipe at a distance of 3 ft downstream of the valve outlet should not exceed 90 dBA (excluding steam conditioning valves). Valve materials shall be ASTM or ASME type carbon steel, chrome moly, or stainless steel, as required by the service conditions. All trim materials shall be stainless steel, as a minimum, with hardened 400 Series stainless steel or Stellite hard surfaced trim where pressure drops exceed 100 psi or wear is expected from erosion. -------------------------------------------------------------------------------- EPC - Exhibit B -------------------- TENASKA GEORGIA GENERATION PROJECT Page 128 of 132 -------------------------------------------------------------------------------- Rotary valves may have plugs similar to body materials but must have alloy steel shafts for corrosion and shear resistance.