NBT 47020-2012
1 Scope
This Standard specifies the classification and specification of pressure vessel flanges, the materials of flanges, studs and nuts and their matching with the gaskets, the maximum allowable working pressure and technical requirements at tall temperaturelevels, as well as the marking.
This Standard is applicable to the flanges of carbon steel and low-alloy steel pressure vessels that the nominal pressure is 0.25MPa~6.40MPa and working temperature is -70℃ ~450℃.
2 Normative References
The following documents are indispensable for the application of this standard. For dated references, only the dated edition is applicable to this document. For undated references, the latest editions of the normative documents (including all the amendments) are applicable to this document.
GB 150 Pressure Vessels
GB/T 196 General Purpose Metric Screw Threads-Basic Dimensions
GB/T 197 General Purpose Metric Screw Threads-Tolerances
GB/T 539 Oil-resisting Asbestos-rubber Sheets
GB/T 699 Quality Carbon Structural Steels
GB/T 700 Carbon Structural Steels
GB 713 Steel Plates for Boiler and Pressure Vessels
GB/T 1801 Geometrical Product Specifications (GPS) - Limits and Fits - Selection of Tolerance Zones and Fits
GB/T 1804 General Tolerances-Tolerances for Linear and Angular Dimensions without Individual Tolerance Indications
GB/T 3077 Alloy Structure Steels
GB/T 3098.2 Mechanical Properties of Fasteners-Nuts-Coarse Thread
GB/T 3274 Hot-rolled Plates and Strips of Carbon Structural Steels and High Strength Low Alloy Structural Steels
GB/T 3985 Asbestos-rubber Sheets
GB/T 5779.2 Fasters - Surface Discontinuities - Nuts
GB/T 16938 Fasteners-General Requirements for Blots, Screws, Studs and Nuts
GB 24511 Stainless Steel Plate, Sheet and Strip for Pressure Equipments
NB/T 47008 Carbon Steel and Alloy Steel Forgings for Pressure Equipments
NB/T 47009 Low-alloy Steel Forgings for Low Temperature Pressure Equipments
NB/T 47021 A-type Socket-weld Flange
NB/T 47022 B-type Socket-weld Flange
NB/T 47023 Welding Neck Flange
NB/T 47024 Nonmetallic Gaskets
NB/T 47025 Spiral Wound Gaskets
NB/T 47026 Double-jacketed Gaskets
NB/T 47027 Fasteners for Pressure Vessel Flanges
JB/T 4730 Nondestructive Testing of Pressure Equipments
3 Selection Principle and Applicable Corrosion Allowance in the Standard
3.1 The flanges specified in this Standard should be selected in priority as the pressure vessel flanges. The calculation in GB 150 may be omitted for the flanges selected according to this Standard.
3.2 The applicable corrosion allowance of B-type flange in this Standard shall not be greater than 2mm; where the corrosion allowance is greater than 2mm but not greater than 3mm, the nipple thickness shall be added by 2mm.The applicable corrosion allowance of welding neck flange shall not be greater than 3mm.
4 Flange Classification, Material Matching, Working Temperature and Maximum Allowable Working Pressure, Physical Dimension
4.1 Flange classification and series parameters are detailed in Table 1.
4.2 Matching of flange, gasket, stud and nut materials
4.2.1 Matching and working temperature range of A-type socket-weld flange, B-type socket-weld flange and long welding neck flange (hereinafter referred to as A-type flange, B-type flange and welding neck flange), gasket, stud and nut materials shall be in accordance with those specified in Table 2.
Contents of NBT 47020-
Foreword i
1 Scope
2 Normative References
3 Selection Principle and Applicable Corrosion Allowance in the Standard
4 Flange Classification, Material Matching, Working Temperature and Maximum Allowable Working Pressure, Physical Dimension
5 Designation, Marking and Marking Sample
6 Technical Specifications
Appendix A (Normative) Specification and Selection of Rolling Flange
