The ASME B16.5 Class 300 Blind Flange is a staple that used to seal the end of a piping system or pressure vessel opening. Unlike weld neck or slip-on flanges, the blind flange has no center bore. It must withstand the full force of the system's internal pressure plus the initial bolting stresses. HT PIPE supply all different types and scales of flanges. Please feel free to contact us for further product information and pricing.
Critical Dimensions for Class 300 Blind Flanges
When sourcing or inspecting these components, four primary measurements dictate the fit and integrity of the seal. For a standard Class 300 flange, the dimensions scale significantly as the Nominal Pipe Size (NPS) increases.
1. Outside Diameter (O)
The total width of the flange. For a 2" Class 300 flange, the O.D. is 6.50 inches, whereas a 12" version jumps to 20.50 inches.
2. Minimum Thickness (tf)
Because blind flanges act as "stoppers," they are often thicker than their counterpart flanges. This thickness ensures the plate doesn't deform under extreme hydrostatic pressure.
3. Bolt Circle Diameter (W)
This is the invisible ring that passes through the center of all bolt holes. Accuracy here is vital for alignment with the mating flange.
4. Number and Diameter of Bolt Holes
Class 300 flanges use a higher density of bolts compared to Class 150 to handle the increased pressure rating.
ASME B16.5 Class 300 Blind Flange Dimensions
