Lap joint Flange

/ Lap joint Flange / By

A lap joint flange is a type of flange used primarily in piping systems where ease of alignment and disassembly is important. It consists of two parts: the lap joint flange itself and a backing flange. Here’s a detailed look at lap joint flanges:

Components and Design:

 

    1. Lap Joint Flange:

       

        • This flange has a circular flange face that is not welded directly to the pipe. Instead, it is designed to slip over the end of the pipe and is often used in conjunction with a backing flange.

        • It typically has a large, flat surface that fits over the pipe or fitting and is usually bolted to a backing flange with a gasket between them to create a seal.

    1. Backing Flange:

       

        • The backing flange is a standard flange with a raised face or flat face. It is bolted to the system and provides a surface for the lap joint flange to be attached.

Features:

 

    • Ease of Installation: The lap joint flange can be easily positioned and aligned with the backing flange, making it ideal for systems where alignment might be challenging.

    • Flexibility: Since the lap joint flange is not welded directly to the pipe, it can be rotated to align with the backing flange’s bolt holes, which is particularly useful in situations where alignment is critical.

    • Disassembly: It allows for easier disassembly and reassembly of the piping system, which is beneficial for maintenance and inspection.

Advantages:

 

    • Alignment: The design allows for easy alignment of bolt holes, which is advantageous in systems where pipes and flanges need to be precisely aligned.

    • Cost: Lap joint flanges are generally less expensive because they do not require the precision machining needed for other flange types like weld neck flanges.

    • Maintenance: They simplify maintenance and inspections because the pipe does not need to be cut or disturbed to remove the flange.

Disadvantages:

 

    • Strength: Lap joint flanges are generally not suitable for high-pressure applications compared to other flanges like weld neck flanges.

    • Space: They require additional space due to the protruding backing flange and the ability to rotate the lap joint flange.

Applications:

 

    • Low-Pressure Systems: Commonly used in low-pressure applications where ease of maintenance and alignment are more important than high-pressure performance.

    • Pipelines: Often used in pipelines where regular disassembly for inspection or cleaning is needed.

Standards and Materials:

 

    • Standards: Lap joint flanges are available in various standards such as ANSI, DIN, and JIS.

    • Materials: They can be made from a variety of materials including carbon steel, stainless steel, and alloy materials, depending on the application requirements.

In summary, lap joint flanges offer flexibility and ease of installation, making them suitable for applications where alignment and maintenance are important, but they might not be the best choice for high-pressure or high-temperature applications.

Dimensions of Class 150 Lap Joint Flanges

All dimensions are in “mm” unless noted otherwise.

Dimensions of Class 150 Lap Joint Flanges as per ASME B16.5.

 

Nominal
Pipe Size		 Outside
diameter of
flange
(D)		 Thick of
flange
(B)		 Diameter of
Hub at base
(A)		 Length
thru Hub
(H)		 Dia of
bore
(ID)		 Fillet
radius
(r)		 No of
holes		 Dia of
holes
(L)		 Dia of
bolts		 Diam of
bolt circle
(K)		 Approx
weight
kg
1/2 88.9 11.2 30.2 15.7 22.9 3 4 15.7 1/2 60.5 0.5
3/4 98.6 12.7 38.1 15.7 28.2 3 4 15.7 1/2 69.9 1
1 108 14.2 49.3 17.5 35.1 3 4 15.7 1/2 79.2 1
1-1/4 117.3 15.7 58.7 20.6 43.7 4.8 4 15.7 1/2 88.9 1
1-1/2 127 17.5 65 22.4 50 6.4 4 15.7 1/2 98.6 1
2 152.4 19.1 77.7 25.4 62.5 7.9 4 19.1 5/8 120.7 2
2-1/2 177.8 22.4 90.4 28.4 75.4 7.9 4 19.1 5/8 139.7 3
3 190.5 23.9 108 30.2 91.4 9.7 4 19.1 5/8 152.4 4
3-1/2 215.9 23.9 122.2 31.8 104.1 9.7 8 19.1 5/8 177.8 5
4 228.6 23.9 134.9 33.3 116.8 11.2 8 19.1 5/8 190.5 6
5 254 23.9 163.6 36.6 144.5 11.2 8 22.4 3/4 215.9 7
6 279.4 25.4 192 39.6 171.5 12.7 8 22.4 3/4 241.3 9
8 342.9 28.4 246.1 44.5 222.3 12.7 8 22.4 3/4 298.5 14
10 406.4 30.2 304.8 49.3 277.4 12.7 12 25.4 7/8 362 20
12 482.6 31.8 365.3 55.6 328.2 12.7 12 25.4 7/8 431.8 29
14 533.4 35.1 400.1 79.2 360.2 12.7 12 28.4 1 476.3 48
16 596.9 36.6 457.2 87.4 411.2 12.7 16 28.4 1 539.8 64
18 635 39.6 505 96.8 462.3 12.7 20 31.8 1-1/8 577.9 73
20 698.5 42.9 558.8 103.1 514.4 12.7 20 31.8 1-1/8 635 88
24 812.8 47.8 663.4 111.3 616 12.7 20 35.1 1-1/4 749.3 125

Dimensions of Class 300 Lap Joint Flanges

All dimensions are in “mm” unless noted otherwise.

Dimensions of Class 300 Lap Joint Flanges as per ASME B16.5.

Nominal
Pipe Size		 Outside
diameter of
flange
(D)		 Thick of
flange
(B)		 Diameter of
Hub at base
(A)		 Length
thru Hub
(H)		 Dia of
bore
(ID)		 Fillet
radius
(r)		 No of
holes		 Dia of
holes
(L)		 Dia of
bolts		 Diam of
bolt circle
(K)		 Approx
weight
kg
1/2 95.3 14.2 38.1 22.4 22.9 3 4 15.7 1/2 66.5 1
3/4 117.3 15.7 47.8 25.4 28.2 3 4 19.1 5/8 82.6 1
1 124 17.5 53.8 26.9 35.1 3 4 19.1 5/8 88.9 1
1-1/4 133.4 19.1 63.5 26.9 43.7 4.8 4 19.1 5/8 98.6 2
1-1/2 155.4 20.6 69.9 30.2 50 6.4 4 22.4 3/4 114.3 3
2 165.1 22.4 84.1 33.3 62.5 7.9 8 19.1 5/8 127 3
2-1/2 190.5 25.4 100.1 38.1 75.4 7.9 8 22.4 3/4 149.4 5
3 209.6 28.4 117.3 42.9 91.4 9.7 8 22.4 3/4 168.1 6
3-1/2 228.6 30.2 133.4 44.5 104.1 9.7 8 22.4 3/4 184.2 8
4 254 31.8 146.1 47.8 116.8 11.2 8 22.4 3/4 200.2 10
5 279.4 35.1 177.8 50.8 144.5 11.2 8 22.4 3/4 235 13
6 317.5 36.6 206.2 52.3 171.5 12.7 12 22.4 3/4 269.7 18
8 381 41.1 260.4 62 222.3 12.7 12 25.4 7/8 330.2 26
10 444.5 47.8 320.5 95.3 277.4 12.7 16 28.4 1 387.4 41
12 520.7 50.8 374.7 101.6 328.2 12.7 16 31.8 1-1/8 450.9 64
14 584.2 53.8 425.5 111.3 360.2 12.7 20 31.8 1-1/8 514.4 86
16 647.7 57.2 482.6 120.7 411.2 12.7 20 35.1 1-1/4 571.5 113
18 711.2 60.5 533.4 130 462.3 12.7 24 35.1 1-1/4 628.7 134
20 774.7 63.5 587.2 139.7 514.4 12.7 24 35.1 1-1/4 685.8 168
24 914.4 69.9 701.5 152.4 616 12.7 24 41.1 1-1/4 812.8 249

Dimensions of Class 600 Lap Joint Flanges

All dimensions are in “mm” unless noted otherwise.

Dimensions of Class 600 Lap Joint Flanges as per ASME B16.5.

Nominal
Pipe Size		 Outside
diameter of
flange
(D)		 Thick of
flange
(B)		 Diameter of
Hub at base
(A)		 Length
thru Hub
(H)		 Dia of
bore
(ID)		 Fillet
radius
(r)		 No of
holes		 Dia of
holes
(L)		 Dia of
bolts		 Diam of
bolt circle
(K)		 Approx
weight
kg
1/2 95.3 14.2 38.1 22.4 22.9 3 4 15.7 1/2 66.5 1
3/4 117.3 15.7 47.8 25.4 28.2 3 4 19.1 5/8 82.6 1
1 124 17.5 53.8 26.9 35.1 3 4 19.1 5/8 88.9 2
1-1/4 133.4 20.6 63.5 28.4 43.7 4.8 4 19.1 5/8 98.6 2
1-1/2 155.4 22.4 69.9 31.8 50 6.4 4 22.4 3/4 114.3 3
2 165.1 25.4 84.1 36.6 62.5 7.9 8 19.1 5/8 127 4
2-1/2 190.5 28.4 100.1 41.1 75.4 7.9 8 22.4 3/4 149.4 5
3 209.6 31.8 117.3 46 91.4 9.7 8 22.4 3/4 168.1 7
3-1/2 228.6 35.1 133.4 49.3 104.1 9.7 8 25.4 7/8 184.2 9
4 273.1 38.1 152.4 53.8 116.8 11.2 8 25.4 7/8 215.9 16
5 330.2 44.5 189 60.5 144.5 11.2 8 28.4 1 266.7 28
6 355.6 47.8 222.3 66.5 171.5 12.7 12 28.4 1 292.1 35
8 419.1 55.6 273.1 76.2 222.3 12.7 12 31.8 1-1/8 349.3 50
10 508 63.5 342.9 111.3 277.4 12.7 16 35.1 1-1/4 431.8 77
12 558.8 66.5 400.1 117.3 328.2 12.7 20 35.1 1-1/4 489 91
14 603.3 69.9 431.8 127 360.2 12.7 20 38.1 1-3/8 527.1 113
16 685.8 76.2 495.3 139.7 411.2 12.7 20 41.1 1-1/2 603.3 166
18 743 82.6 546.1 152.4 462.3 12.7 20 44.5 1-5/8 654.1 197
20 812.8 88.9 609.6 165.1 514.4 12.7 24 44.5 1-5/8 723.9 259
24 939.8 101.6 717.6 184.2 616 12.7 24 50.8 1-7/8 838.2 367

Dimensions of Class 900 Lap Joint Flanges

All dimensions are in “mm” unless noted otherwise.

Dimensions of Class 900 Lap Joint Flanges as per ASME B16.5.

Nominal
Pipe Size		 Outside
diameter of
flange
(D)		 Thick of
flange
(B)		 Diameter of
Hub at base
(A)		 Length
thru Hub
(H)		 Dia of
bore
(ID)		 Fillet
radius
(r)		 No of
holes		 Dia of
holes
(L)		 Dia of
bolts		 Diam of
bolt circle
(K)		 Approx
weight
kg
1/2 120.7 22.4 38.1 31.8 22.9 3 4 22.4 3/4 82.6 2
3/4 130 25.4 44.5 35.1 28.2 3 4 22.4 3/4 88.9 2
1 149.4 28.4 52.3 41.1 35.1 3 4 25.4 7/8 101.6 4
1-1/4 158.8 28.4 63.5 41.1 43.7 4.8 4 25.4 7/8 111.3 4
1-1/2 177.8 31.8 69.9 44.5 50 6.4 4 28.4 1 124 5
2 215.9 38.1 104.6 57.2 62.5 7.9 8 25.4 7/8 165.1 11
2-1/2 244.3 41.1 124 63.5 75.4 7.9 8 28.4 1 190.5 16
3 241.3 38.1 127 53.8 91.4 9.7 8 25.4 7/8 190.5 11
4 292.1 44.5 158.8 69.9 116.8 11.2 8 31.8 1-1/8 235 23
5 349.3 50.8 190.5 79.2 144.5 11.2 8 35.1 1-1/4 279.4 37
6 381 55.6 235 85.9 171.5 12.7 12 31.8 1-1/8 317.5 48
8 469.9 63.5 298.5 114.3 222.3 12.7 12 38.1 1-3/8 393.7 86
10 546.1 69.9 368.3 127 277.4 12.7 16 38.1 1-3/8 469.9 125
12 609.6 79.2 419.1 142.7 328.2 12.7 20 38.1 1-3/8 533.4 168
14 641.4 85.9 450.9 155.4 360.2 12.7 20 41.1 1-1/2 558.8 188
16 704.9 88.9 508 165.1 411.2 12.7 20 44.5 1-5/8 616 211
18 787.4 101.6 565.2 190.5 462.3 12.7 20 50.8 1-7/8 685.8 295
20 857.3 108 622.3 209.6 514.4 12.7 20 53.8 2 749.3 367
24 1041.4 139.7 749.3 266.7 616 12.7 20 66.5 2-1/2 901.7 703

Dimensions of Class 1500 Lap Joint Flanges

All dimensions are in “mm” unless noted otherwise.

Dimensions of Class 1500 Lap Joint Flanges as per ASME B16.5.

Nominal
Pipe Size		 Outside
diameter of
flange
(D)		 Thick of
flange
(B)		 Diameter of
Hub at base
(A)		 Length
thru Hub
(H)		 Dia of
bore
(ID)		 Fillet
radius
(r)		 No of
holes		 Dia of
holes
(L)		 Dia of
bolts		 Diam of
bolt circle
(K)		 Approx
weight
kg
1/2 120.7 22.4 38.1 31.8 22.9 3 4 22.4 3/4 82.6 2
3/4 130 25.4 44.5 35.1 28.2 3 4 22.4 3/4 88.9 2
1 149.4 28.4 52.3 41.1 35.1 3 4 25.4 7/8 101.6 4
1-1/4 158.8 28.4 63.5 41.1 43.7 4.8 4 25.4 7/8 111.3 4
1-1/2 177.8 31.8 69.9 44.5 50 6.4 4 28.4 1 124 5
2 215.9 38.1 104.6 57.2 62.5 7.9 8 25.4 7/8 165.1 11
2-1/2 244.3 41.1 124 63.5 75.4 7.9 8 28.4 1 190.5 16
3 266.7 47.8 133.4 73.2 91.4 9.7 8 31.8 1-1/8 203.2 21
4 311.2 53.8 162.1 90.4 116.8 11.2 8 35.1 1-1/4 241.3 34
5 374.7 73.2 196.9 104.6 144.5 11.2 8 41.1 1-1/2 292.1 64
6 393.7 82.6 228.6 119.1 171.5 12.7 12 38.1 1-3/8 317.5 77
8 482.6 91.9 292.1 142.7 222.3 12.7 12 44.5 1-5/8 393.7 129
10 584.2 108 368.3 177.8 277.4 12.7 12 50.8 1-7/8 482.6 220
12 673.1 124 450.9 218.9 328.2 12.7 16 53.8 2 571.5 286
14 749.3 133.4 495.3 241.3 360.2 12.7 16 60.5 2-1/4 635 404
16 825.5 146.1 552.5 260.4 411.2 12.7 16 66.5 2-1/2 704.9 476
18 914.4 162.1 596.9 276.4 462.3 12.7 16 73.2 2-3/4 774.7 669
20 984.3 177.8 641.4 292.1 514.4 12.7 16 79.2 3 831.9 805
24 1168.4 203.2 762 330.2 616 12.7 16 91.9 3-1/2 990.6 1281

Dimensions of Class 2500 Lap Joint Flanges

All dimensions are in “mm” unless noted otherwise.

Dimensions of Class 2500 Lap Joint Flanges as per ASME B16.5.

Nominal
Pipe Size		 Outside
diameter of
flange
(D)		 Thick of
flange
(B)		 Diameter of
Hub at base
(A)		 Length
thru Hub
(H)		 Dia of
bore
(ID)		 Fillet
radius
(r)		 No of
holes		 Dia of
holes
(L)		 Dia of
bolts		 Diam of
bolt circle
(K)		 Approx
weight
kg
1/2 133.4 30.2 42.9 39.6 22.9 3 4 22.4 3/4 88.9 3
3/4 139.7 31.8 50.8 42.9 28.2 3 4 22.4 3/4 95.3 4
1 158.8 35.1 57.2 47.8 35.1 3 4 25.4 7/8 108 5
1-1/4 184.2 38.1 73.2 52.3 43.7 4.8 4 28.4 1 130 7
1-1/2 203.2 44.5 79.2 60.5 50 6.4 4 31.8 1-1/8 146.1 10
2 235 50.8 95.3 69.9 62.5 7.9 8 28.4 1 171.5 17
2-1/2 266.7 57.2 114.3 79.2 75.4 7.9 8 31.8 1-1/8 196.9 24
3 304.8 66.5 133.4 91.9 91.4 9.7 8 35.1 1-1/4 228.6 36
4 355.6 76.2 165.1 108 116.8 11.2 8 41.1 1-1/2 273.1 54
5 419.1 91.9 203.2 130 144.5 11.2 8 47.8 1-3/4 323.9 93
6 482.6 108 235 152.4 171.5 12.7 8 53.8 2 368.3 143
8 552.5 127 304.8 177.8 222.3 12.7 12 53.8 2 438.2 213
10 673.1 165.1 374.7 228.6 277.4 12.7 12 66.5 2-1/2 539.8 408
12 762 184.2 441.5 254 328.2 12.7 12 73.2 2-3/4 619.3 499