How to order Pipe Flanges – Part 1 (con't)
Dimensional standards are the same for all materials. In other words, the dimensions of a 6” ASME B16.5 Class 150 flange will be the same for carbon steel, stainless steel, Alloy 20 or aluminum. More information on materials can be found in Part 4.
Final note on standards. Standards are continually revised, broadened and evolving. And so are the standards organizations. For instance the flange standard B16.5 was first published by ASA. That changed to ANSI and then to ANSI/ASME and now it is just ASME. It is very common for specifications to include reference to older publications and presumed that the most current standard be utilized.
Step 2 – Define the Pressure Class
Pressure class further defines flange dimensions. The pressure class is not the pressure limit of the flange; it is more like a starting point.
This chart shows the pressure classes defined by each of the standards listed.
| ANSI B16.1 | ASME B16.24 | ASME B16.47 Series A | ASME B16.47 Series B | ASME B16.5 | AWWA C207 | AWWA C115 | API 6A | API 17D | ISO 7005 |
|---|---|---|---|---|---|---|---|---|---|
| Class 125 | Class 150 | Class 150 | Class 75 | Class 150 | Class B | Class 125 | 2000 PSI | 5000 PSI | PN2.5 |
| Class 250 | Class 300 | Class 300 | Class 150 | Class 300 | Class D | 3000 PSI | 10000 PSI | PN6 | |
| Class 400 | Class 400 | Class 300 | Class 400 | Class E | 5000 PSI | 15000 PSI | PN10 | ||
| Class 600 | Class 600 | Class 400 | Class 600 | Class F | 10000 PSI | PN16 | |||
| Class 900 | Class 900 | Class 600 | Class 900 | 15000 PSI | PN25 | ||||
| Class 1500 | Class 900 | Class 1500 | 20000 PSI | PN40 | |||||
| Class 2500 | Class 2500 |
There are 4 factors that determine the actual working pressure and pressure limits of flanges within each pressure class.
- The dimensions; the diameter, thickness, number and size of bolts.
- The material; even though the pressure class and dimensions are the same for all materials in each standard, the actual pressure and temperature limits are different for every material.
- The temperature; as internal and/or external temperatures increase pressure limits decrease.
- The size; within some pressure classes, the limits will be less for larger pipe sizes.
The following charts are examples of flange pressure/temperature ratings. These charts have been compiled from reliable sources; however they are NOT a substitute for professional engineering and they are not applicable to all applications. Please use these charts as a reference only. For critical applications please consult a qualified engineer.
ANSI B16.1 A126B Cast Iron Maximum Working Pressure (psig)
| Pressure Class | 125 | 125 | 125 | 250 | 250 |
|---|---|---|---|---|---|
| Temperature (F) | 1"-12" Pipe Size | 14"-24" Pipe Size | 30"-48" Pipe Size | 1"-12" Pipe Size | 14"-24" Pipe Size |
| -20 up to 150 | 200 | 150 | 150 | 500 | 300 |
| 200 | 190 | 135 | 115 | 460 | 280 |
| 225 | 180 | 130 | 100 | 440 | 270 |
| 250 | 175 | 125 | 85 | 415 | 260 |
| 275 | 170 | 120 | 65 | 395 | 250 |
| 300 | 165 | 110 | 50 | 375 | 240 |
| 325 | 155 | 105 | - | 355 | 230 |
| 350 | 150 | 100 | - | 335 | 220 |
| 375 | 145 | - | - | 315 | 210 |
| 400 | 140 | - | - | 290 | 200 |
| 425 | 130 | - | - | 270 | - |
| 450 | 125 | - | - | 250 | - |
ASME B16.5 A105 Forged Carbon Steel Maximum Working Pressure (psig)
| Pressure Class | 150 | 300 | 400 | 600 | 900 | 1500 | 2500 |
|---|---|---|---|---|---|---|---|
| Temperature (F) | 1/2"-24" Pipe Size | 1/2"-24" Pipe Size | 1/2"-24" Pipe Size | 1/2"-24" Pipe Size | 3"-24" Pipe Size | 1/2"-24" Pipe Size | 1/2"-12" Pipe Size |
| -20 to 100 | 290 | 750 | 1000 | 1500 | 2250 | 3750 | 6250 |
| 200 | 260 | 750 | 1000 | 1500 | 2250 | 3750 | 6250 |
| 300 | 230 | 730 | 970 | 1455 | 2185 | 3640 | 6070 |
| 400 | 200 | 705 | 940 | 1405 | 2110 | 3520 | 5865 |
| 500 | 170 | 665 | 885 | 1330 | 1995 | 3325 | 5540 |
| 600 | 140 | 605 | 805 | 1210 | 1815 | 3025 | 5040 |
| 650 | 125 | 590 | 785 | 1175 | 1765 | 2940 | 4905 |
| 700 | 110 | 555 | 740 | 1110 | 1665 | 2775 | 4630 |
| 750 | 95 | 505 | 675 | 1015 | 1520 | 2535 | 4230 |
| 800 | 80 | 410 | 550 | 825 | 1235 | 2055 | 3430 |
ASME B16.5 A182 F316L Stainless Steel Maximum Working Pressure (psig)
| Pressure Class | 150 | 300 | 400 | 600 | 900 | 1500 | 2500 |
|---|---|---|---|---|---|---|---|
| Temperature (F) | 1/2"-24" Pipe Size | 1/2"-24" Pipe Size | 1/2"-24" Pipe Size | 1/2"-24" Pipe Size | 3"-24" Pipe Size | 1/2"-24" Pipe Size | 1/2"-12" Pipe Size |
| -20 to 100 | 230 | 600 | 800 | 1200 | 1800 | 3000 | 5000 |
| 200 | 195 | 505 | 675 | 1015 | 1520 | 2530 | 4220 |
| 300 | 175 | 455 | 605 | 910 | 1360 | 2270 | 3780 |
| 400 | 160 | 415 | 550 | 825 | 1240 | 2065 | 3440 |
| 500 | 145 | 380 | 510 | 765 | 1148 | 1910 | 3180 |
| 600 | 140 | 360 | 480 | 720 | 1080 | 1800 | 3000 |
| 650 | 125 | 350 | 470 | 700 | 1050 | 1750 | 2920 |
| 700 | 110 | 345 | 460 | 685 | 1030 | 1715 | 2860 |
| 750 | 95 | 335 | 450 | 670 | 1010 | 1680 | 2800 |
| 800 | 80 | 330 | 440 | 660 | 985 | 1645 | 2740 |
Because the pressure class determines the bolting dimensions and the pressure limits, this must be defined when ordering pipe flanges. If you have any questions, please contact one of our friendly sales people. We are eager to help!
Step 3 - Define the Flange Facing