1.0.1 This national standard specifies the basic technical requirements of steel pipe flanges (Class designated), including nominal dimension, nominal pressure, material, pressure-temperature rating, flange type, dimension, sealing face, tolerance and marking.
1.0.2 This Standard is applicable to steel pipe flange and blind flange with nominal pressure of Classl50 (PN20)~Class2500 (PN420). The nominal pressure grade of the flange is denoted by Class, including the following six grades: Classl50, Class300, Class600, Class900, Classl500 and Class2500.
Table 1.0.2 Nominal Pressure Grade Synopses of Flange
Class PN Class PN
Classl50 PN20 Class900 PN150
Class300 PN50 Class1500 PN260
Class600 PN110 Class2500 PN420
1.0.3 The applied nominal dimension DN and outside diameter of the steel pipe in this Standard are in accordance with those specified in Table 1.0.3.
Table 1.0.3 Nominal Dimension and Outside Diameter of the Steel Pipe (mm)
Nominal dimension DN 15 20 25 32 40 50 65 80 100
NPS 1/2 3/4 1 1 1/4 1 1/2 2 2 1/2 3 4
Outside diameter of the steel pipe 21.3 26.9 33.7 42.4 48.3 60.3 76.1 88.9 114.3
Nominal dimension DN 125 150 200 250 300 350 400 450 500 600
NPS 5 6 8 10 12 14 16 18 20 24
Outside diameter of the steel pipe 139.7 168.3 219.1 273.0 323.9 355.6 406.4 457 508 610
1.0.4 This Standard is also applicable to valve, pump, chemical engineering machinery, pipeline fittings and equipment spares with flange being used as its type of attachment.
1.0.5 This Standard excludes selection principle for materials under particular fluid operating conditions.
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2. Normative references
The following standards contain provisions which, through reference in this text, constitute provisions of this Standard. For dated reference, subsequent amendments (excluding content of corrigenda) to, or revisions of, any of these publications do not apply. However, Parties to agreements based on this Code are encouraged to investigate the possibility of applying the most recent editions of the standards indicated below. For undated references, the latest edition of the normative document referred to applies.
"Pipework Components--Definition and Selection of DN (Nominal Dimension)" GB/T 1047
"Steel Pressure Vessels" GB 150
"Fasteners-Clearance Holes and Counterbores" GB/T 152.1~152.4
"Carbon Structural Steels" GB/T 700
"Hot-rolled Quality Carbon Structural Steel Plates and Wide Strips" GB/T 711
"Steel Plates for Boiler and Pressure Vessels" GB 713
"Hot-rolled Plates and Strips of Carbon Structural Steels and High Strength Low Alloy Structural Steels" GB/T 3274
"Low Alloy Steel Plates for Low Temperature Pressure Vessels" GB 3531
"Hot Rolled Stainless Steel Plate Sheet and Strip" GB/T 4237
"Pipe Threads with 55 Degree Thread Angle where Pressure-tight Joints are Made on the Threads--Part 2: Taper Internal and External Threads" GB/T 7306.2
"General Purpose Industrial Valves-Specification of Carbon Steel Forgings" GB/T 12228
"General Purpose Industrial Valves-Specification of Carbon Steel Castings" GB/T 12229
"General Purpose Industrial Valve-Specification of Stainless Steel Castings" GB/T 12230
"Pipe Threads with the Thread Angle of 60 Degrees where Pressure-Tight Joints are Made on the Threads" GB/T 12716
"Steel Castings for Pressure Purposes" GB/T 16253
"Dimension Selection Series of Seamless and Welded Steel Pipe for Chemical Industry Piping" HG/T 20553
"Non-metallic Flat Gaskets for use with Steel Pipe Flanges (Class designated)" HG/T 20627
"PTFE Envelope Gaskets for use with Steel Pipe Flanges (Class designated))" HG/T 20628
1. General provisions
2. Normative references
3. Flange style and flange sealing surface
3.1 Flange type
3.2 Flange sealing face
4. Materials
5. Gaskets and bolting for flange
6. Fitting of flange joint
7. Pressure-temperature rating
8. Dimensions
8.1 Coupling dimension of the pipe flange
8.2 Physical dimension of the pipe flange
8.3 Pipe flange neck
8.4 Pipe thread
9. Welding joint and groove dimension
10. Dimension tolerance
11. Test
12. Inspection and acceptance
13. Markings and illustrations
14. Packaging and steel seal labeling
Appendix A (Normative) Steel Orifice Flange
Appendix B (Informative) Steel Jacket Flange
Appendix C (Informative) Inside Diameter of the Weld Neck Pipe Flange
Appendix D (Informative) Assorted Pipe Flanges' Standard
Appendix E (Informative) Approximate Mass of the Pipe Flanges
Appendix F (Informative) Approximate Distance between the Ring Joint Face Flanges
