Lap Joint flange dimensions are covered in ASME B16.5 – which covers Pipe Flanges and Flanged Fittings for size NPS ½” to 24” for above NPS 26” to 60” it should be as per ASME B16.47.

During a dimensional inspection of a lap flange, you should check for

  • Outer & Inner Diameter of body
  • Bolt Circle & Bolt hole Diameter
  • Length of the Hub
  • Straightness and alignment of the bolt hole
lap joint flange dimensions

Class 150 Lap Joint Flange Dimensions

Size in Inch Size in mm Outer Diameter Flange Thick. Lapped Thick. Lapped ID PCD Lapped Thick. Lapped Radius 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 G
1/2 15 90 30 16 22.9 60.3 11.2 3 4 1/2 50 55 5/8 M14 0.8
3/4 20 100 38 16 28.2 69.9 12.7 3 4 1/2 50 65 5/8 M14 0.9
1 25 110 49 17 34.9 79.4 14.3 3 4 1/2 55 65 5/8 M14 0.9
1 1/4 32 115 59 21 43.7 88.9 15.9 5 4 1/2 55 70 5/8 M14 1.4
1 1/2 40 125 65 22 50 98.4 17.5 6 4 1/2 65 70 5/8 M14 1.4
2 50 150 78 25 62.5 120.7 19.1 8 4 5/8 70 85 3/4 M16 2.3
2 1/2 65 180 90 29 75.4 139.7 22.3 8 4 5/8 75 90 3/4 M16 3.2
3 80 190 108 30 91.4 152.4 23.9 10 4 5/8 75 90 3/4 M16 3.7
3 1/2 90 215 122 32 104.1 177.8 23.9 11 8 5/8 75 90 3/4 M16 5
4 100 230 135 33 116.8 190.5 23.9 11 8 5/8 75 90 3/4 M16 5.9
5 125 255 164 36 144.4 215.9 23.9 11 8 3/4 85 95 7/8 M20 6.8
6 150 280 192 40 171.4 241.3 25.4 13 8 3/4 85 100 7/8 M20 8.6
8 200 345 246 44 222.2 298.5 28.6 13 8 3/4 90 110 7/8 M20 13.7
10 250 405 305 49 277.4 362 30.2 13 12 7/8 100 115 1 M24 19.5
12 300 485 365 56 328.2 431.8 31.8 13 12 7/8 100 120 1 M24 29
14 350 535 400 79 360.2 476.3 35 13 12 1 115 135 1 1/8 M27 41
16 400 595 457 87 411.2 539.8 36.6 13 16 1 115 135 1 1/8 M27 54
18 450 635 505 97 462.3 577.9 39.7 13 16 1 1/8 125 145 1 1/4 M30 59
20 500 700 559 103 514.4 635 42.9 13 20 1 1/8 140 160 1 1/4 M30 75
24 600 815 663 111 616 749.3 47.9 13 20 1 1/4 150 170 1 3/8 M33 100

Flange and Olet Quiz – Test yourself, Take This Quiz

Class 300 Lap Joint Flange Dimensions

Size in Inch Size in mm Outer Diameter Flange Thick. Lapped Thick. Lapped ID PCD Lapped Thick. Lapped Radius 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 G
1/2 15 95 38 22 22.9 66.7 14.3 3 4 1/2 55 65 5/8 M14 1.2
3/4 20 115 48 25 28.2 82.6 15.9 3 4 5/8 65 75 3/4 M16 1.4
1 25 125 54 27 34.9 88.9 17.5 3 4 5/8 65 75 3/4 M16 1.4
1 1/4 32 135 64 27 43.7 98.4 19.1 5 4 5/8 70 85 3/4 M16 1.8
1 1/2 40 155 70 30 50 114.3 20.7 6 4 3/4 75 90 7/8 M20 2.7
2 50 165 84 33 62.5 127 22.3 8 8 5/8 75 90 3/4 M16 3.2
2 1/2 65 190 100 38 75.4 149.2 25.4 8 8 3/4 85 100 7/8 M20 4.6
3 80 210 117 43 91.4 168.3 28.6 10 8 3/4 90 110 7/8 M20 5.9
3 1/2 90 230 133 44 104.1 184.2 30.2 11 8 3/4 95 110 7/8 M20 7.7
4 100 255 146 48 116.8 200 31.8 11 8 3/4 95 115 7/8 M20 10
5 125 280 178 51 144.4 235 35 11 8 3/4 110 120 7/8 M20 12.7
6 150 320 206 52 171.4 269.9 36.6 13 12 3/4 110 120 7/8 M20 17.7
8 200 380 260 62 222.2 330.2 41.3 13 12 7/8 120 140 1 M24 26
10 250 445 321 95 277.4 387.4 47.7 13 16 1 140 160 1 1/8 M27 36
12 300 520 375 102 328.2 450.8 50.8 13 16 1 1/8 145 170 1 1/4 M30 52
14 350 585 425 111 360.2 514.4 54 13 20 1 1/8 160 180 1 1/4 M30 75
16 400 650 483 121 411.2 571.5 57.2 13 20 1 1/4 165 190 1 3/8 M33 86
18 450 710 533 130 462.3 628.6 60.4 13 24 1 1/4 170 195 1 3/8 M33 113
20 500 775 587 140 514.4 685.8 63.5 13 24 1 1/4 185 205 1 3/8 M33 143
24 600 915 702 153 616 812.8 69.9 13 24 1 1/2 205 230 1 5/8 M39 216

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Class 400 Lap Joint Flange Dimensions

Size in Inch Size in mm Outer Diameter Flange Thick. Lapped Thick. Lapped ID PCD Lapped Thick. Lapped Radius No of Bolts Bolt Size UNC RF Stud Length Hole Size ISO Stud Size Weight in kg
A B C D E G
1/2 15 95 38 22 22.9 66.7 14.3 3 4 1/2 75 5/8 M14 1.3
3/4 20 115 48 25 28.2 82.6 15.9 3 4 5/8 90 3/4 M16 1.5
1 25 125 54 27 34.9 88.9 17.5 3 4 5/8 90 3/4 M16 1.8
1 1/4 32 135 64 29 43.7 98.4 20.7 5 4 5/8 95 3/4 M16 2.3
1 1/2 40 155 70 32 50 114.3 22.3 6 4 3/4 110 7/8 M20 3.2
2 50 165 84 37 62.5 127 25.4 8 8 5/8 110 3/4 M16 4.1
2 1/2 65 190 100 41 75.4 149.2 28.6 8 8 3/4 120 7/8 M20 5.9
3 80 210 117 46 91.4 168.3 31.8 10 8 3/4 125 7/8 M20 7.3
3 1/2 90 230 133 49 104.1 184.2 35 10 8 7/8 140 1 M24 9.6
4 100 255 146 51 116.8 200 35 11 8 7/8 140 1 M24 11.8
5 125 280 178 54 144.5 235 38.1 11 8 7/8 145 1 M24 14.1
6 150 320 206 57 171.4 269.9 41.3 13 12 7/8 150 1 M24 20
8 200 380 260 68 222.2 330 47.7 13 12 1 170 1 1/8 M27 31
10 250 445 321 102 277.4 387.4 54 13 16 1 1/8 190 1 1/4 M30 42
12 300 520 375 108 328.2 450.8 57.2 13 16 1 1/4 205 1 3/8 M33 59
14 350 585 425 117 360.2 514.4 60.4 13 20 1 1/4 210 1 3/8 M33 82
16 400 650 483 127 411.2 571.5 63.5 13 20 1 3/8 220 1 1/2 M36 107
18 450 710 533 137 462.3 628.6 66.7 13 24 1 3/8 230 1 1/2 M36 130
20 500 775 587 146 514.4 685.8 69.9 13 24 1 1/2 240 1 3/4 M39 157
24 600 915 702 159 616 812.8 76.2 13 24 1 3/4 265 1 7/8 M45 232

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Class 600 Lap Joint Flange Dimensions

Size in Inch Size in mm Outer Diameter Flange Thick. Lapped Thick. Lapped ID PCD Lapped Thick. Lapped Radius No of Bolts Bolt Size UNC RF Stud Length Hole Size ISO Stud Size Weight in kg
A B C D E G
1/2 15 95 38 22 22.9 66.7 14.3 3 4 1/2 75 5/8 M14 1.3
3/4 20 115 48 25 28.2 82.6 15.9 3 4 5/8 90 3/4 M16 1.4
1 25 125 54 27 34.9 88.9 17.5 3 4 5/8 90 3/4 M16 1.8
1 1/4 32 135 64 29 43.7 98.4 20.7 5 4 5/8 95 3/4 M16 2.3
1 1/2 40 155 70 32 50 114.3 22.3 6 4 3/4 110 7/8 M20 3.2
2 50 165 84 37 62.5 127 25.4 8 8 5/8 110 3/4 M16 4.1
2 1/2 65 190 100 41 75.4 149.2 28.6 8 8 3/4 120 7/8 M20 5.9
3 80 210 117 46 91.4 168.3 31.8 10 8 3/4 125 7/8 M20 7.3
3 1/2 90 230 133 49 104.1 184.2 35 11 8 7/8 140 1 M24 9.6
4 100 275 152 54 116.8 215.9 38.1 11 8 7/8 145 1 M24 16.8
5 125 330 189 60 144.4 266.7 44.5 11 8 1 165 1 1/8 M27 29
6 150 355 222 67 171.4 292.1 47.7 13 12 1 170 1 1/8 M27 36
8 200 420 273 76 222.2 349.2 55.6 13 12 1 1/8 190 1 1/4 M30 52
10 250 510 343 111 277.4 431.8 63.5 13 16 1 1/4 215 1 3/8 M33 77
12 300 560 400 117 328.2 489 66.7 13 20 1 1/4 220 1 3/8 M33 91
14 350 605 432 127 360.2 527 69.9 13 20 1 3/8 235 1 1/2 M36 105
16 400 685 495 140 411.2 603.2 76.2 13 20 1 1/2 255 1 5/8 M39 150
18 450 745 546 152 462.3 654 82.6 13 20 1 5/8 275 1 3/4 M42 182
20 500 815 610 165 514.4 723.9 88.9 13 24 1 5/8 285 1 3/4 M42 232
24 600 940 718 184 616 838.2 101.6 13 24 1 7/8 330 2 M48 332

Class 900 Lap Joint Flange Dimensions

Size in Inch Size in mm Outer Diameter Flange Thick. Lapped Thick. Lapped ID PCD Lapped Thick. Lapped Radius No of Bolts Bolt Size UNC RF Stud Length Hole Size ISO Stud Size Weight in kg
A B C D E G
1/2 15 120 38 32 22.9 82.6 22.3 3 4 3/4 110 7/8 M20 1.8
3/4 20 130 44 35 28.2 88.9 25.4 3 4 3/4 115 7/8 M20 2.3
1 25 150 52 41 34.9 101.6 28.6 3 4 7/8 125 1 M24 3.6
1 1/4 32 160 64 41 43.7 111.1 28.6 5 4 7/8 125 1 M24 4.1
1 1/2 40 180 70 44 50 123.8 31.8 6 4 1 140 1 1/8 M27 5.5
2 50 215 105 57 62.5 165.1 38.1 8 8 7/8 145 1 M24 11.5
2 1/2 65 245 124 64 75.4 190.5 41.3 8 8 1 160 1 1/8 M27 16.5
3 80 240 127 54 91.4 190.5 38.1 10 8 7/8 145 1 M24 12
4 100 290 159 70 116.8 235 44.5 11 8 1 1/8 170 1 1/4 M30 24
5 125 350 190 79 144.4 279.4 50.8 11 8 1 1/4 190 1 3/8 M33 38
6 150 380 235 86 171.4 317.5 55.6 13 12 1 1/8 190 1 1/4 M30 50
8 200 470 298 114 222.2 393.7 63.5 13 12 1 3/8 220 1 1/2 M36 78
10 250 545 368 127 277.4 469.9 69.9 13 16 1 3/8 235 1 1/2 M36 112
12 300 610 419 143 328.2 533.4 79.4 13 20 1 3/8 255 1 1/2 M36 148
14 350 640 451 156 360.2 558.8 85.8 13 20 1 1/2 275 1 5/8 M39 182
16 400 705 508 165 411.2 616 88.9 13 20 1 5/8 285 1 3/4 M42 193
18 450 785 565 190 462.3 685.8 101.6 13 20 1 7/8 325 2 M48 258
20 500 855 622 210 514.4 749.3 108 13 20 2 350 2 1/8 M52 317
24 600 1040 749 267 616 901.7 139.7 13 20 2 1/2 440 2 5/8 M64 608

Class 1500 Lap Joint Flange Dimensions

Size in Inch Size in mm Outer Diameter Flange Thick. Lapped Thick. Lapped ID PCD Lapped Thick. Lapped Radius No of Bolts Bolt Size UNC RF Stud Length Hole Size ISO Stud Size Weight in kg
A B C D E G
1/2 15 120 38 32 22.9 82.6 22.3 3 4 3/4 110 7/8 M20 1.8
3/4 20 130 44 35 28.2 88.9 25.4 3 4 3/4 115 7/8 M20 2.3
1 25 150 52 41 34.9 101.6 28.6 3 4 7/8 125 1 M24 3.7
1 1/4 32 160 64 41 43.7 111.1 28.6 5 4 7/8 125 1 M24 4.1
1 1/2 40 180 70 44 50 123.8 31.8 6 4 1 140 1 1/8 M27 5.5
2 50 215 105 57 62.5 165.1 38.1 8 8 7/8 145 1 M24 9.8
2 1/2 65 245 124 64 75.4 190.5 41.3 8 8 1 160 1 1/8 M27 16.4
3 80 265 133 73 91.4 203.2 47.7 10 8 1 1/8 180 1 1/4 M30 21.8
4 100 310 162 90 116.8 241.3 54 11 8 1 1/4 195 1 3/8 M33 33
5 125 375 197 105 144.4 292.1 73.1 11 8 1 1/2 250 1 5/8 M39 59
6 150 395 229 119 171.4 317.5 82.6 13 12 1 3/8 260 1 1/2 M36 75
8 200 485 292 143 222.2 393.7 92.1 13 12 1 5/8 290 1 3/4 M42 118
10 250 585 368 178 277.4 482.6 108 13 12 1 7/8 335 2 M48 198
12 300 675 451 219 328.2 571.5 123.9 13 16 2 375 2 1/8 M52 264
14 350 750 495 241 360.2 635 133.4 13 16 2 1/4 405 2 3/8 M56 341
16 400 825 552 260 411.2 704.8 146.1 13 16 2 1/2 445 2 5/8 M64 454
18 450 915 597 276 462.3 774.7 162 13 16 2 3/4 495 2 7/8 M72 590
20 500 985 641 292 514.4 831.8 177.8 13 16 3 540 3 1/8 M76 792
24 600 1170 762 330 616 990.6 203.2 13 16 3 1/2 615 3 5/8 M90 1248

Class 2500 Lap Joint Flange Dimensions

Size in Inch Size in mm Outer Diameter Flange Thick. Lapped Thick. Lapped ID PCD Lapped Thick. Lapped Radius No of Bolts Bolt Size UNC RF Stud Length Hole Size ISO Stud Size Weight in kg
A B C D E G
1/2 15 135 43 40 22.9 88.9 30.2 3 4 3/4 120 7/8 M20 3.2
3/4 20 140 51 43 28.2 95.2 31.8 3 4 3/4 125 7/8 M20 3.7
1 25 160 57 48 34.9 108 35 3 4 7/8 140 1 M24 5
1 1/4 32 185 73 52 43.7 130.2 38.1 5 4 1 150 1 1/8 M27 7.5
1 1/2 40 205 79 60 50 146 44.5 6 4 1 1/8 170 1 1/4 M30 10
2 50 235 95 70 62.5 171.4 50.9 8 8 1 180 1 1/8 M27 17.5
2 1/2 65 265 114 79 75.4 196.8 57.2 8 8 1 1/8 195 1 1/4 M30 23
3 80 305 133 92 91.4 228.6 66.7 10 8 1 1/4 220 1 3/8 M33 37.8
4 100 355 165 108 116.8 273 76.2 11 8 1 1/2 255 1 5/8 M39 57
5 125 420 203 130 144.4 323.8 92.1 11 8 1 3/4 300 1 7/8 M45 95
6 150 485 235 152 171.4 368.3 108 13 8 2 345 2 1/8 M52 148
8 200 550 305 178 222.2 438.2 127 13 12 2 380 2 1/8 M52 221
10 250 675 375 229 277.4 539.8 165.1 13 12 2 1/2 490 2 5/8 M64 425
12 300 760 441 254 328.2 619.1 184.2 13 12 2 3/4 540 2 7/8 M72 500

Disclaimer –  Please check with ASME B16.5 Before using.

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About Author

Varun Patel, B.E – Mechanical, PMP®

19+ years of experience in the oil and gas sector, specializing in project management, contracts, project control, project coordination, QA/QC and inspection of large-scale Greenfield and Brownfield Projects such as Refinery, Petrochemical, Wellhead production, and Process platform. Proven track record of delivering large-scale projects while ensuring adherence to safety and quality standards. Skilled in leading and mentoring cross-functional teams and resolving technical issues to achieve successful project outcomes.