【正文】 ty of the transverse balance by the expansion joint 7 1. General Provisions The purpose of this specification is to direct the design of the water/steam pipeline of fossil fuel power plant to ensure a secure, fullload, and economical operation. This specification is suitable for the steam/water piping design in the fossil fuel power plant with the unit main steam parameter as 27MPa, 550℃ (high temperature and reheated steam can be as high as 565℃ ) or below. The steam/water piping design within the generating units and the furnace shall not only ply with this specification, but also needs to be determined after being negotiated with the manufacturer. The heating work pipe and the pipe for transferring oil and air inside the power plant can refer to this specification. This specification is not suitable for the designs of fuel pipeline, fuel gas pipeline, hydrogen gas pipeline and underground straight buried pipe. Related standards quoted by this specification: Nominal diameter of the pipeline parts (3131047) Nominal pressure of the pipeline parts (3131048) Seamless steel pipe shall be used for highpressure boiler (385310) For low and mediapressure boiler, seamless steel pipe is used (GB3087) Carbon construction steel (313700) Spiral welded steel pipe (SY5036~5039) Lowpressure stream conveyance with welding steel pipe (3133092) Steel pressure vessel (GB150) Carbon steel covered electrode (GB5117) Low alloy structural steel (GB5118) Technical specifications on pipeline stress calculation of fossil fuel power plant (SDGJ6) Electric power construction and technical specification for the acceptance (pipeline section) (DJ56) Electric power construction and technical specification for the acceptance (Welding in fossil fuel power plant) (DL5007) Electric power construction and technical specification for the acceptance (Radio examination of the steel loadbearing pipeline buttjointed seams) (SD143) Metallic technical supervision specification of the fossil fuel power plant (DLA38) Supervision code for boiler of power industry (SDl67) 8 2 General policy conditions Design specifications Piping design shall be carried out according to the thermodynamic system and setup. It requires good material sources, proper setup, good indemnification, smooth drainage, smaller flow resistance, low construction cost, appropriate hanger and support, convenient installation as well as maintenance, flexible extension, and shall be tidy and nice in appearance. Hydraulic impact and resonance shall be avoided, and noise shall be reduced. Piping design shall ply with related standards and specifications of the state and the ministry. Design parameter Design pressure Piping design pressure (gauge pressure) refers to the maximal working pressure of the interior media in service. For the utility of water pipe and design pressure, the influence of water column39。 1 Professional Standard of the Popeple’s Republic of China DL/T 50541996 Technical Specification for the Steam/Water Piping Design of Fossil Fuel Power Plant 火力發(fā)電廠汽水管道設(shè)計技術(shù)規(guī)定 2 Notice on the issuing of power industry standard Electric Power Industry of People Republic of China Dian Ji [1996] After inspection and approval, Technical Specification for the Steam/Water Piping Design of Fossils Fuel Power Plant is approved to be a reference specification and is hereby issued. The standard code is: DL/T 50541996 This standard shall be implemented from October 1, 1996. Please notify the Ministry of Electric Industry, Electric Power Planning and Design General Institution of the problems and suggestions during the specification‘s implementation, also a copy of it shall be sent to the office of ministry standardization leading group. This standard is under the charge of China Water Power Press to publish. 3 Unit and meaning of the frequently used symbols: Symbol Unit Meaning P MPa designed pressure PN MPa nominative pressure PT MPa test pressure Pd Pa, MPa dynamical pressure of the media inside the pipe Pd1 Pa, MPa dynamical pressure at the initial end of the pipe Pd2 Pa, MPa dynamical pressure of the pipe end PO Pa, MPa stagnation pressure at the initial end of the pipe P1 Pa, MPa pressure at the initial end of the pipe P2 Pa, MPa pressure of the pipe end PC Pa, MPa critical pressure of the media inside the pipe Pd Pa, MPa critical dynamical pressure of the media inside the pipe α ratio of the pressure at the initial end of the pipe and the pressure at the end of the space αc ratio of the pressure at the initial end of the pipe and the critical pressure t ℃ design temperature or working temperature ter ℃ design installation temperature αb20 MPa minimal tensile strength of the steel products at 20℃ α 3 MPa minimal yield limit of the steel products at design temperature αt3 (%) MPa minimal yield limit when the steel products residual deformation is % at design temperature ? tD MPa 100, 000 h average endurable strength of the steel materials at design temperature 4 [? ]T MPa safe allowable stress of the steel products at design temperature ? safe allowable stress pensation factor DN mm inside nominal diameter DO mm pipe external diameter Di mm internal pipe size sm mm minimal straight pipe wall thickness SC mm calculated wall thickness of the straight pipe S mm wall thickness of the straight pipe A negative deviation coefficient of the pipe thickness G t/h media mass flow Gmax t/h media maximal mass flow Gmin t/h media minimal mass flow Q m3/h media volumetric flow v m3/kg media specific volume v0 m3/kg pipeline initial end stagnation specific volume v1 m3/kg media specific volume at the pipe initial v2 m3/kg media specific volume at the