Lap Joint Flange
Lap Joint Flange
A Lap Joint Flange is a type of pipe flange comprising two parts: a flat, circular disc (the “stub end”) and a ring or hub (the “lap joint”). The stub end is typically welded to the pipe or fitting, while the lap joint rotates freely around it. This design facilitates easy alignment during assembly.
These flanges are commonly used in piping systems where frequent dismantling and reassembly are necessary, such as those handling corrosive or abrasive fluids or in systems with thermal expansion considerations. They offer versatility, allowing for adjustments and disassembly without disturbing the entire piping system.
Lap joint flanges come in various materials, sizes, and facings to suit different applications and operating conditions. They are available with flat face (FF), raised face (RF), or ring type joint (RTJ) facings, depending on sealing requirements.
Features of Lap Joint Flange:
- Two-Piece Design:
- Consists of a flange and a stub end.
- The flange is free to rotate around the stub end, allowing for easy bolt alignment during assembly.
- Material Compatibility:
- The flange itself can be made from a lower-grade material, as it does not come into contact with the fluid. The stub end, which makes the connection, is made from a material compatible with the piping material.
- Easy Alignment:
- The rotating feature ensures that bolt holes can be aligned without the need for precise adjustments to the piping.
- Cost-Efficiency:
- Reduces cost by enabling the use of economical materials for the flange when high-grade materials are used only for the stub end.
- Low-Pressure Applications:
- Primarily used in low-pressure applications and systems that do not experience extreme mechanical stress.
- Ease of Maintenance:
- Simplifies disassembly and reassembly, making it ideal for applications requiring frequent cleaning or inspection.
Lap Joint Flange Dimensions Class 150
| 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 |
Lap Joint Flange Weight Chart
| Flange Size (inches) | Class 150 (lbs) | Class 300 (lbs) | Class 400 (lbs) | Class 600 (lbs) | Class 900 (lbs) | Class 1500 (lbs) | Class 2500 (lbs) |
|---|---|---|---|---|---|---|---|
| ½ | 1 | 2 | 2 | 2 | 6 | 6 | 7 |
| ¾ | 2 | 3 | 3 | 3 | 6 | 6 | 8 |
| 1 | 2 | 3 | 3.5 | 4 | 7.5 | 8 | 12 |
| 1¼ | 3 | 4.5 | 4.5 | 5 | 10 | 10 | 17 |
| 1½ | 3 | 6.5 | 6.5 | 7 | 14 | 14 | 24 |
| 2 | 5 | 7 | 8 | 9 | 21 | 25 | 37 |
| 2½ | 8 | 10 | 11 | 12 | 25 | 35 | 53 |
| 3 | 9 | 14.5 | 14 | 15 | 29 | 47 | 80 |
| 3½ | 11 | 17 | 20 | 20 | 51 | 75 | 122 |
| 4 | 13 | 24 | 25 | 36 | 81 | 140 | 204 |
| 5 | 15 | 28 | 29 | 63 | 105 | 170 | 314 |
| 6 | 19 | 39 | 42 | 78 | 190 | 286 | 471 |
| 8 | 30 | 58 | 64 | 112 | 277 | 485 | 897 |
| 10 | 43 | 91 | 110 | 195 | 371 | 749 | 1262 |
| 12 | 64 | 140 | 152 | 240 | 415 | 890 | – |
| 14 | 105 | 190 | 210 | 290 | 488 | 1250 | – |
| 16 | 140 | 234 | 280 | 400 | 670 | 1475 | – |
| 18 | 160 | 305 | 345 | 469 | 868 | 1775 | – |
| 20 | 195 | 375 | 420 | 604 | 1659 | 2825 | – |
| 22 | 245 | 435 | 455 | 670 | – | – | – |
| 24 | 275 | 550 | 615 | 866 | – | – | – |
Advantages of Lap Joint Flanges
- Easy alignment during installation.
- Reusability, as the flange does not come into direct contact with the fluid.
- Reduced material costs, as the flange can be made from a less expensive material compared to the stub end.
Pressure Ratings
- Class 150 (PN 20)
- Class 300 (PN 50)
- Class 400 (PN 64)
- Class 600 (PN 100)
- Class 900 (PN 150)
- Class 1500 (PN 250)
- Class 2500 (PN 420)
Applications:
- Petrochemical and chemical processing industries.
- Food and beverage processing plants.
- Water treatment facilities.
- Pharmaceutical manufacturing.
- Systems requiring easy dismantling, such as temporary piping layouts or inspection points.
