ASME B16.5 Class 300 Flange Dimensions
ASME B16.5 specifies the dimensions, materials, pressure-temperature ratings, and testing for flanges used in pressure piping systems. Class 300 flanges are typically used for medium-pressure applications, and their dimensions are crucial for selecting the correct flange for your system.
Here's an overview of the dimensions for ASME B16.5 Class 300 flanges for various types:
1. Bolt Circle Diameter (BCD) and Number of Bolt Holes
The bolt circle diameter (BCD) is the diameter of the circle formed by the center of the bolt holes. The number of bolt holes typically depends on the size of the flange. Below is a general overview:
| Nominal Pipe Size (NPS) | Bolt Circle Diameter (BCD) | Number of Bolt Holes |
|---|---|---|
| 1" | 2.625" | 4 |
| 1.5" | 3.250" | 4 |
| 2" | 4.000" | 4 |
| 2.5" | 4.500" | 4 |
| 3" | 5.000" | 4 |
| 4" | 6.000" | 8 |
| 5" | 7.000" | 8 |
| 6" | 7.500" | 8 |
| 8" | 9.000" | 8 |
| 10" | 10.000" | 8 |
| 12" | 11.000" | 8 |
| 14" | 12.000" | 8 |
| 16" | 13.500" | 12 |
| 18" | 14.500" | 12 |
| 20" | 15.500" | 12 |
2. Flange Face Type
Class 300 flanges may come in different face types, such as:
Raised Face (RF): The most common type, where the sealing surface is raised above the flange's body.
Flat Face (FF): The sealing surface is at the same level as the flange's body.
Ring Joint (RJ): Used in high-pressure applications, where a metal ring is inserted into the flange's groove.
3. Dimensions of Class 300 Flanges (Flat Face and Raised Face)
| NPS | Face to Face (Dimension A) | Bolt Hole Diameter (B) | Nominal Thickness (C) | Raised Face (RF) Height (D) |
|---|---|---|---|---|
| 1" | 0.750" | 0.438" | 0.88" | 0.062" |
| 1.5" | 0.875" | 0.500" | 1.00" | 0.062" |
| 2" | 1.000" | 0.500" | 1.13" | 0.062" |
| 3" | 1.250" | 0.625" | 1.38" | 0.062" |
| 4" | 1.500" | 0.750" | 1.88" | 0.062" |
| 5" | 1.750" | 0.875" | 2.00" | 0.062" |
| 6" | 2.000" | 1.000" | 2.25" | 0.062" |
| 8" | 2.375" | 1.250" | 2.50" | 0.062" |
| 10" | 2.750" | 1.375" | 2.88" | 0.062" |
| 12" | 3.125" | 1.500" | 3.25" | 0.062" |
| 14" | 3.500" | 1.750" | 3.63" | 0.062" |
| 16" | 3.875" | 2.000" | 4.00" | 0.062" |
| 18" | 4.250" | 2.250" | 4.50" | 0.062" |
| 20" | 4.625" | 2.500" | 4.75" | 0.062" |
4. Other Dimensions and Features
Hub Diameter (H): The diameter of the flange's central hole, which allows it to fit over the pipe or pipe fitting.
Thickness (T): The thickness of the flange body, which determines its ability to withstand pressure.
Bolt Hole Pitch (P): The distance between the centers of adjacent bolt holes, which is typically equal to the bolt circle diameter divided by the number of bolts.
5. Pressure Rating for Class 300 Flanges
Class 300 flanges can withstand pressures up to approximately 300 psi at room temperature. The pressure tolerance decreases with increasing temperatures. Here's an example of how the pressure rating varies with temperature:
| Temperature (°F) | Pressure (psi) |
|---|---|
| 100°F (38°C) | 300 psi |
| 200°F (93°C) | 275 psi |
| 300°F (149°C) | 250 psi |
| 400°F (204°C) | 225 psi |
| 500°F (260°C) | 200 psi |
Conclusion
ASME B16.5 Class 300 flanges offer a reliable and cost-effective solution for medium-pressure applications. They come in a range of sizes, materials, and face types to meet the specific needs of different piping systems. Selecting the appropriate flange dimensions ensures that your system will perform efficiently and safely.
If you have any specific requirements or need further assistance with flange selection, feel free to ask!
