Flow Elements Sample Clauses
Flow Elements. Flowmeters shall preferably be those of the differential pressure type with an accuracy of "1 percent of the span maintained over a 10:1 flow turndown. The materials of the meters and their associated parts shall not be deteriorated by the working fluid. Flow transmitters shall have output linear with differential pressure with an accuracy of within "0.5 percent of full scale range. Flow metering primary elements and installations shall be designed in accordance with ASME "Fluid Meters" Part Two, "Application of Fluid Meters". Primary elements shall be ASME long radius flow nozzles or thin plate square edge concentric orifices as appropriate to system operating conditions and as described herein. Steam flows shall be measured with ASME long radius flow nozzles. Annubars are not acceptable. The Contractor shall be responsible for verifying that sufficient length of straight pipe is provided on each side of all primary elements. Any internal boring of adjacent pipe shall be by the Contractor. The pressure taps for flow nozzles shall be installed in the pipe well as described in "Fluid Meters" Part Two. Orifices shall be installed between specially designed orifice flanges. Where required, flow metering shall be temperature and/or pressure compensated. For flow metering of oil, positive displacement meters or area meters shall be provided. For flow metering of fuel gas to the gas turbine, an orifice plate meter run shall be provided. Condensing reservoirs shall be provided on all flow transmitter services where low differential pressures relative to the static pressure are present in steam service. Condensing reservoir inlet and outlet connections shall be a minimum of 20 mm. -------------------------------------------------------------------------------- EPC - Exhibit B -------------------- TENASKA GEORGIA GENERATION PROJECT Page 129 of 132 -------------------------------------------------------------------------------- - Nozzles - Flow nozzles shall be constructed of Type 304 stainless steel and shall be designed in accordance with Paragraphs II-III-20 through II-III-26 of the ASME report "Fluid Meters," Part Two Application of Fluid Meters - Especially Differential Pressure types. - Orifice Plates - Orifice plates shall be constructed of Type 304 or 316 stainless steel. Orifice plates shall not be less than 1/8 inch thick for nominal pipe diameters up to and including 12 inches, and shall not be less than 1/4 inch thick for nominal pipe diameters above 12 ...
Flow Elements. Orifice Plates Orifice plates of the square-edged concentric type shall be specified except where unsatisfactory for the application. Plate dimensions shall conform to ASME MFC-3M. Weep holes shall be provided in steam and gas flow installations where there is possible condensation or in liquid flow where there is possible gas entrainment. Materials shall normally be Type 304 stainless steel unless special materials are required for the service. For gas and vapor service, the differential pressure range in inches of water normally shall not exceed the static absolute pressure in psia. Orifice bores will be calculated using ASME MFC-3M and ISO 5167. Flange taps shall normally be used in accordance with ASME MFC-3M. For special alloys and 14-inch-and-larger pipe sizes, in 150-psi classification, throat taps may be used. One-half-inch NPT is the normal tap size for 300 psi through 600 psi flange rating. Three-quarter-inch is the tap size for 900 psi through 2,500 psi flange rating. Where threaded connections are not permitted by the pipe class, socket weld connections shall be used. The minimum orifice flange rating shall be 300 psi ANSI except for lines 14 inches and larger, where 150 psi ANSI is the minimum. The use of higher rated flanges, or of facing type, shall be as called for in piping specifications. Ring-type plate holders shall be manufacturer's standard plate mounting. Ring facing shall be oval ANSI standard unless otherwise required by piping specifications. Orifice taps for horizontal pipe runs shall normally be oriented horizontal for clean liquids and steam, and vertical-up for gases. Venturi tubes, low-loss tubes, and flow nozzles shall be used where high-pressure recovery is necessary and/or where only low inlet pressure is available. Averaging pitot tubes shall be used where the pipe diameter is too large for acceptable orifice plate design in applications such as pump minimum flow bypass control, or where normal straight pipe requirements are not met. The element may have two pipe diameters of straight pipe upstream and downstream mounted in a plane parallel to the maximum disturbance. Other types of flow elements should be considered where their use is desirable and the above-mentioned elements are not applicable. Integral orifice meters (combination primary element-measuring device) shall normally be used for meter runs of less than 1.5 inches with a suitable strainer upstream of the meter. Eccentric type orifice plates shall be used for...
Flow Elements. Flow Nozzles and Venturis Venturi nozzles shall also be used for all flows used for primary control. Orifice plates may be used for other flow measurements. Flow transmitters will be the differential pressure type with the range matching (as closely as practical) the primary element. Linear scales and charts will be used for flow indication and recording. Critical steam and natural gas flow meters (if applicable) will be temperature and/or pressure compensated, and air flow measurements will be temperature compensated. Differential pressure type instruments shall normally be used for flow measurements where suitable for the application. Flow transmitters shall be the essentially zero volume displacement differential pressure type. Bodies shall normally be carbon steel with stainless steel internal trim, unless other materials are required for the particular services. Overrange protection equal to the body rating shall be provided. Wherever possible, the maximum differential range in inches of water shall not exceed the static absolute pressure in psia in a compressible fluid application. Span shall be continuously adjustable over at least a 5:1 ratio. Variable area flow meters may be used for small flow rates where local indication is required. They may also be used where rangeability, nonlinearity, viscosity, or the hazardous nature of the fluid makes the differential pressure-type instrument unsatisfactory. They shall normally be the armored type with magnetic pick-up, except for water and air below 200 psig and 1-inch-or-smaller lines where glass tubes may be used. All glass tube area meters shall have front and rear plastic guard plates. Positive displacement meters shall be used to measure those flows where a highly accurate integrated flowing quantity is desired.
Flow Elements. Averaging pitot type (Annubar) or flanged orifice plate devices shall be used, in general, for flow measurement at the Contractor's discretion. Flow nozzles shall be used for critical measurements. They shall be of the weld-in type, flow nozzle sections with two (2) sets of pipe wall pressure taps. Calibration of the flow nozzle section shall be provided where greater accuracy is required than manufacturer's standard uncalibrated accuracy guarantee. In general, averaging pitot type devices and flow nozzles shall be stainless steel.