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carbon steel blind flange
Blind Flange Diagram

ASTM A105 Blind Flange

ASTM A105 Blind Flange

SpecificationDetails
StandardASTM A105 / ASME SA105
Flange TypeBlind Flange (BLFF/BLRF/BLRTJ)
Pressure ClassClass 150, 300, 600, 900, 1500, 2500
Size Range½” to 60” (DN15 – DN1500)
Manufacturing ProcessForged, Heat-treated
Face TypeRF, FF, RTJ
Surface FinishSerrated Finish / Spiral & Concentric
Test CertificatesEN 10204 3.1 / 3.2
StandardsASME B16.5 / B16.47 / MSS-SP-44
Category:

ASTM A105 / SA 105 Blind Flange

ASTM A105 Blind Flanges are forged carbon steel flanges designed to close the end of piping systems, valves, or pressure vessel openings. They are widely used in high-pressure and high-temperature applications across industries such as oil & gas, petrochemical, power generation, and refineries.

Manufactured from premium-grade carbon steel, A105 Blind Flanges provide excellent strength, durability, and resistance to stress and corrosion under aggressive operating conditions. These flanges are ideal for testing the flow in piping systems, enabling easy reopening for maintenance or inspection when required.

Key Features

  • High tensile & yield strength
  • Suitable for high-temperature & high-pressure services
  • Excellent resistance to wear & corrosion
  • Precise dimensional accuracy & surface finish
  • Compatible with standard gasket & bolt connections
  • Available in raised face (RF), flat face (FF), and ring-type joint (RTJ)

ASTM A105 Chemical Composition

Element Content (%)
Carbon (C) ≤ 0.35
Manganese (Mn) 0.60 – 1.05
Silicon (Si) 0.10 – 0.35
Phosphorus (P) ≤ 0.035
Sulfur (S) ≤ 0.040

ASTM A105 Mechanical Properties

Property Value
Tensile Strength 485 MPa (70 ksi) min
Yield Strength 250 MPa (36 ksi) min
Elongation 22% min
Hardness 187 HBW max

Blind Flange Dimensions – Class 150 to Class 2500

Class 150 Blind Flange Dimensions

Size
in Inch		 Size
in mm		 Outer
Dia.		 Flange
Thick.		 RF
Dia.		 RF
Height		 PCD No of
Bolts		 Bolt Size
UNC		 Machine Bolt
Length		 RF Stud
Length		 Hole Size ISO Stud
Size		 Weight
in kg
A B C D E
1/2 15 90 9.6 34.9 2 60.3 4 1/2 50 55 5/8 M14 0.9
3/4 20 100 11.2 42.9 2 69.9 4 1/2 50 65 5/8 M14 0.9
1 25 110 12.7 50.8 2 79.4 4 1/2 55 65 5/8 M14 0.9
1 1/4 32 115 14.3 63.5 2 88.9 4 1/2 55 70 5/8 M14 1.4
1 1/2 40 125 15.9 73 2 98.4 4 1/2 65 70 5/8 M14 1.8
2 50 150 17.5 92.1 2 120.7 4 5/8 70 85 3/4 M16 2.3
2 1/2 65 180 20.7 104.8 2 139.7 4 5/8 75 90 3/4 M16 3.2
3 80 190 22.3 127 2 152.4 4 5/8 75 90 3/4 M16 4.1
3 1/2 90 215 22.3 139.7 2 177.8 8 5/8 75 90 3/4 M16 5.9
4 100 230 22.3 157.2 2 190.5 8 5/8 75 90 3/4 M16 7.7
5 125 255 22.3 185.7 2 215.9 8 3/4 85 95 7/8 M20 9.1
6 150 280 23.9 215.9 2 241.3 8 3/4 85 100 7/8 M20 11.8
8 200 345 27 269.9 2 298.5 8 3/4 90 110 7/8 M20 20.5
10 250 405 28.6 323.8 2 362 12 7/8 100 115 1 M24 32
12 300 485 30.2 381 2 431.8 12 7/8 100 120 1 M24 50
14 350 535 33.4 412.8 2 476.3 12 1 115 135 1 1/8 M27 64
16 400 595 35 469.9 2 539.8 16 1 115 135 1 1/8 M27 82
18 450 635 38.1 533.4 2 577.9 16 1 1/8 125 145 1 1/4 M30 100
20 500 700 41.3 584.2 2 635 20 1 1/8 140 160 1 1/4 M30 130
24 600 815 46.1 692.2 2 749.3 20 1 1/4 150 170 1 3/8 M33 196

Class 300 Blind Flange Dimensions

Size
in Inch		 Size
in mm		 Outer
Dia.		 Flange
Thick.		 RF
Dia.		 RF
Height		 PCD No of
Bolts		 Bolt Size
UNC		 Machine Bolt
Length		 RF Stud
Length		 Hole
Size		 ISO Stud
Size		 Weight
in kg
A B C D E
1/2 15 95 12.7 34.9 2 66.7 4 1/2 55 65 5/8 M14 1.4
3/4 20 115 14.3 42.9 2 82.6 4 5/8 65 75 3/4 M16 1.4
1 25 125 15.9 50.8 2 88.9 4 5/8 65 75 3/4 M16 1.4
1 1/4 32 135 17.5 63.5 2 98.4 4 5/8 70 85 3/4 M16 1.8
1 1/2 40 155 19.1 73 2 114.3 4 3/4 75 90 7/8 M20 2.7
2 50 165 20.7 92.1 2 127 8 5/8 75 90 3/4 M16 3.7
2 1/2 65 190 23.9 104.8 2 149.2 8 3/4 85 100 7/8 M20 5.5
3 80 210 27 127 2 168.3 8 3/4 90 110 7/8 M20 7.3
3 1/2 90 230 28.6 139.7 2 184.2 8 3/4 95 110 7/8 M20 9.6
4 100 255 30.2 157.2 2 200 8 3/4 95 115 7/8 M20 12.3
5 125 280 33.4 185.7 2 235 8 3/4 110 120 7/8 M20 15.9
6 150 320 35 215.9 2 269.9 12 3/4 110 120 7/8 M20 22.7
8 200 380 39.7 269.9 2 330.2 12 7/8 120 140 1 M24 36
10 250 445 46.1 323.8 2 387.4 16 1 140 160 1 1/8 M27 57
12 300 520 49.3 381 2 450.8 16 1 1/8 145 170 1 1/4 M30 84
14 350 585 52.4 412.8 2 514.4 20 1 1/8 160 180 1 1/4 M30 113
16 400 650 55.6 469.9 2 571.5 20 1 1/4 165 190 1 3/8 M33 134
18 450 710 58.8 533.4 2 628.6 24 1 1/4 170 195 1 3/8 M33 181
20 500 775 62 584.2 2 685.8 24 1 1/4 185 205 1 3/8 M33 230
24 600 915 68.3 692.2 2 812.8 24 1 1/2 205 230 1 5/8 M39 359

Class 400 Blind Flange Dimensions

Size
in Inch		 Size
in mm		 Outer
Dia.		 Flange
Thick.		 RF
Dia.		 RF
Height		 PCD No of
Bolts		 Bolt Size
UNC		 RF Stud
Length		 Hole
Size		 ISO Stud
Size		 Weight
in kg
A B C D E
1/2 15 95 14.3 34.9 7 66.7 4 1/2 75 5/8 M14 1.5
3/4 20 115 15.9 42.9 7 82.6 4 5/8 90 3/4 M16 1.5
1 25 125 17.5 50.8 7 88.9 4 5/8 90 3/4 M16 1.8
1 1/4 32 135 20.7 63.5 7 98.4 4 5/8 95 3/4 M16 2.3
1 1/2 40 155 22.3 73 7 114.3 4 3/4 110 7/8 M20 3.7
2 50 165 25.4 92.1 7 127 8 5/8 110 3/4 M16 4.6
2 1/2 65 190 28.6 104.8 7 149.2 8 3/4 120 7/8 M20 6.8
3 80 210 31.8 127 7 168.3 8 3/4 125 7/8 M20 9.1
3 1/2 90 230 35 N/A 7 184.2 8 7/8 140 1 M24 13.2
4 100 255 35 157.2 7 200 8 7/8 140 1 M24 15
5 125 280 38.1 185.7 7 235 8 7/8 145 1 M24 20
6 150 320 41.3 215.9 7 269.9 12 7/8 150 1 M24 28
8 200 380 47.7 269.9 7 330 12 1 170 1 1/8 M27 46
10 250 445 54 323.8 7 387.4 16 1 1/8 190 1 1/4 M30 71
12 300 520 57.2 381 7 450.8 16 1 1/4 205 1 3/8 M33 102
14 350 585 60.4 412.8 7 514.4 20 1 1/4 210 1 3/8 M33 132
16 400 650 63.5 469.9 7 571.5 20 1 3/8 220 1 1/2 M36 168
18 450 710 66.7 533.4 7 628.6 24 1 3/8 230 1 1/2 M36 207
20 500 775 69.9 584.2 7 685.8 24 1 1/2 240 1 3/4 M39 266
24 600 915 76.2 692.2 7 812.8 24 1 3/4 265 1 7/8 M45 405

Class 600 Blind Flange Dimensions

Size in Inch Size in mm Outer Dia. Flange Thick. RF Dia. RF Height PCD No of Bolts Bolt Size UNC RF Stud Length Hole Size ISO Stud Size Weight in kg
A B C D E
1/2 15 95 14.3 34.9 7 66.7 4 1/2 75 5/8 M14 1.4
3/4 20 115 15.9 42.9 7 82.6 4 5/8 90 3/4 M16 1.4
1 25 125 17.5 50.8 7 88.9 4 5/8 90 3/4 M16 1.8
1 1/4 32 135 20.7 63.5 7 98.4 4 5/8 95 3/4 M16 2.3
1 1/2 40 155 22.3 73 7 114.3 4 3/4 110 7/8 M20 3.7
2 50 165 25.4 92.1 7 127 8 5/8 110 3/4 M16 4.6
2 1/2 65 190 28.6 104.8 7 149.2 8 3/4 120 7/8 M20 6.8
3 80 210 31.8 127 7 168.3 8 3/4 125 7/8 M20 9.1
3 1/2 90 230 35 N/A 7 184.2 8 7/8 140 1 M24 13.2
4 100 275 38.1 157.2 7 215.9 8 7/8 145 1 M24 18.7
5 125 330 44.5 185.7 7 266.7 8 1 165 1 1/8 M27 31
6 150 355 47.7 215.9 7 292.1 12 1 170 1 1/8 M27 39
8 200 420 55.6 269.9 7 349.2 12 1 1/8 190 1 1/4 M30 64
10 250 510 63.5 323.8 7 431.8 16 1 1/4 215 1 3/8 M33 105
12 300 560 66.7 381 7 489 20 1 1/4 220 1 3/8 M33 134
14 350 605 69.9 412.8 7 527 20 1 3/8 235 1 1/2 M36 161
16 400 685 76.2 469.9 7 603.2 20 1 1/2 255 1 5/8 M39 225
18 450 745 82.6 533.4 7 654 20 1 5/8 275 1 3/4 M42 286
20 500 815 88.9 584.2 7 723.9 24 1 5/8 285 1 3/4 M42 368
24 600 940 101.6 692.2 7 838.2 24 1 7/8 330 2 M48 568

Class 900 Blind Flange Dimensions

Size in Inch Size in mm Outer Dia. Flange Thick. RF Dia. RF Height PCD No of  Bolts Bolt Size UNC RF Stud Length Hole Size ISO Stud Size Weight in kg
A B C D E
1/2 15 120 22.3 34.9 7 82.6 4 3/4 110 7/8 M20 1.8
3/4 20 130 25.4 42.9 7 88.9 4 3/4 115 7/8 M20 2.7
1 25 150 28.6 50.8 7 101.6 4 7/8 125 1 M24 3.6
1 1/4 32 160 28.6 63.5 7 111.1 4 7/8 125 1 M24 4.1
1 1/2 40 180 31.8 73 7 123.8 4 1 140 1 1/8 M27 5.9
2 50 215 38.1 92.1 7 165.1 8 7/8 145 1 M24 10.1
2 1/2 65 245 41.3 104.8 7 190.5 8 1 160 1 1/8 M27 16
3 80 240 38.1 127 7 190.5 8 7/8 145 1 M24 13
4 100 290 44.5 157.2 7 235 8 1 1/8 170 1 1/4 M30 24.5
5 125 350 50.8 185.7 7 279.4 8 1 1/4 190 1 3/8 M33 39.5
6 150 380 55.6 215.9 7 317.5 12 1 1/8 190 1 1/4 M30 53
8 200 470 63.5 269.9 7 393.7 12 1 3/8 220 1 1/2 M36 91
10 250 545 69.9 323.8 7 469.9 16 1 3/8 235 1 1/2 M36 132
12 300 610 79.4 381 7 533.4 20 1 3/8 255 1 1/2 M36 189
14 350 640 85.8 412.8 7 558.8 20 1 1/2 275 1 5/8 M39 237
16 400 705 88.9 469.9 7 616 20 1 5/8 285 1 3/4 M42 273
18 450 785 101.6 533.4 7 685.8 20 1 7/8 325 2 M48 367
20 500 855 108 584.2 7 749.3 20 2 350 2 1/8 M52 463
24 600 1040 139.7 692.2 7 901.7 20 2 1/2 440 2 5/8 M64 875

Class 1500 Blind Flange Dimensions

Size in Inch Size in mm Outer Dia. Flange Thick. RF Dia. RF Height PCD No of Bolts Bolt Size UNC RF Stud Length Hole Size ISO Stud Size Weight in kg
A B C D E
1/2 15 120 22.3 34.9 7 82.6 4 3/4 110 7/8 M20 1.8
3/4 20 130 25.4 42.9 7 88.9 4 3/4 115 7/8 M20 2.7
1 25 150 28.6 50.8 7 101.6 4 7/8 125 1 M24 3.7
1 1/4 32 160 28.6 63.5 7 111.1 4 7/8 125 1 M24 4.1
1 1/2 40 180 31.8 73 7 123.8 4 1 140 1 1/8 M27 5.9
2 50 215 38.1 92.1 7 165.1 8 7/8 145 1 M24 10.1
2 1/2 65 245 41.3 104.8 7 190.5 8 1 160 1 1/8 M27 15.9
3 80 265 47.7 127 7 203.2 8 1 1/8 180 1 1/4 M30 21.8
4 100 310 54 157.2 7 241.3 8 1 1/4 195 1 3/8 M33 33
5 125 375 73.1 185.7 7 292.1 8 1 1/2 250 1 5/8 M39 64
6 150 395 82.6 215.9 7 317.5 12 1 3/8 260 1 1/2 M36 75
8 200 485 92.1 269.9 7 393.7 12 1 5/8 290 1 3/4 M42 136
10 250 585 108 323.8 7 482.6 12 1 7/8 335 2 M48 232
12 300 675 123.9 381 7 571.5 16 2 375 2 1/8 M52 314
14 350 750 133.4 412.8 7 635 16 2 1/4 405 2 3/8 M56 443
16 400 825 146.1 469.9 7 704.8 16 2 1/2 445 2 5/8 M64 591
18 450 915 162 533.4 7 774.7 16 2 3/4 495 2 7/8 M72 795
20 500 985 177.8 584.2 7 831.8 16 3 540 3 1/8 M76 1022
24 600 1170 203.2 692.2 7 990.6 16 3 1/2 615 3 5/8 M90 1648

Class 2500 Blind Flange Dimensions

Size in Inch Size in mm Outer Dia. Flange Thick. RF Dia. RF Height PCD No of  Bolts Bolt Size UNC RF Stud Length Hole Size ISO Stud Size Weight in kg
A B C D E
1/2 15 135 30.2 34.9 7 88.9 4 3/4 120 7/8 M20 3.2
3/4 20 140 31.8 42.9 7 95.2 4 3/4 125 7/8 M20 3.7
1 25 160 35 50.8 7 108 4 7/8 140 1 M24 5
1 1/4 32 185 38.1 63.5 7 130.2 4 1 150 1 1/8 M27 7.8
1 1/2 40 205 44.5 73 7 146 4 1 1/8 170 1 1/4 M30 10.5
2 50 235 50.9 92.1 7 171.4 8 1 180 1 1/8 M27 18
2 1/2 65 265 57.2 104.8 7 196.8 8 1 1/8 195 1 1/4 M30 25.5
3 80 305 66.7 127 7 228.6 8 1 1/4 220 1 3/8 M33 39
4 100 355 76.2 157.2 7 273 8 1 1/2 255 1 5/8 M39 61.5
5 125 420 92.1 185.7 7 323.8 8 1 3/4 300 1 7/8 M45 102
6 150 485 108 215.9 7 368.3 8 2 345 2 1/8 M52 157
8 200 550 127 269.9 7 438.2 12 2 380 2 1/8 M52 241
10 250 675 165.1 323.8 7 539.8 12 2 1/2 490 2 5/8 M64 470
12 300 760 184.2 381 7 619.1 12 2 3/4 540 2 7/8 M72 575

Applications

  • Oil & Gas Pipelines
  • Petrochemical Plants
  • Power Generation & Boilers
  • Refineries & Chemical Industry
  • Water Treatment & Process Plants
  • High-Pressure Pipe End Closure & Testing

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