Bronze Blind Flanges Manufacturer & Exporter
A blind flange is a solid disc that closes the end of a pipe, nozzle or valve opening. Without a bore it isolates a line section for pressure testing, maintenance or future extension.
Product Overview
Blind flanges are the simplest component in a flanged system and one of the most heavily loaded: the full cross-section sees line pressure, so the disc works in bending between the bolt circle and the gasket. Material strength, thickness and bolting layout matter more than they do on a bored flange.
Product specification
SM-PRD-BLI| Parameter | Specification |
|---|---|
| Product | Bronze blind flange |
| Materials | UNS C93200, C95400, C95500, C95800, C63000, C83600, C84400 |
| Dimensional basis | Applicable standard or customer drawing |
| Thickness | Per class table or design calculation |
| Pressure class | Class 150 / 300 or per drawing, as applicable |
| Facing | FF / RF / custom |
| Bore | None (solid disc); optional tapped port |
| Marking | MSS SP-25 pattern or customer requirement |
| Documentation | MTC and inspection documents as applicable |
Technical Description
Thickness, material and facing are fixed by the class table or by your design calculation. For non-standard pressures or large diameters, the design check belongs to the system designer; we machine to the thickness and drilling on the drawing. Because the face is the only sealing surface, flatness and finish of the gasket area are inspected closely.
Construction
- Solid disc with no bore
- Flat or raised face, finish per MSS SP-6 or customer requirement
- Drilling to the specified class pattern or drawing
- Optional drilled and tapped port for gauge or vent, on request
- Marking of grade, class and heat or lot reference, per purchase order
Available Materials
Available materials
SM-MAT-BLI| Grade | Alloy | Stock and specification | Fit for this flange |
|---|---|---|---|
| UNS C93200 | Leaded tin bronze (SAE 660) | Cast: ASTM B584 / B271 / B505 | General-service closures where machinability matters |
| UNS C95400 | Aluminium bronze | Cast: ASTM B148 / B271 / B505 | General marine and pump-system blanking |
| UNS C95500 | Nickel aluminium bronze | Cast: ASTM B148 / B271 / B505 | Higher-strength closures at heavier classes |
| UNS C95800 | Nickel aluminium bronze (NAB) | Cast: ASTM B148 / B271 / B505 | Seawater and offshore end closures; high-strength nickel aluminium bronze |
| UNS C63000 | Wrought nickel aluminium bronze | Bar, forging, plate: ASTM B150 / B124 / B283 / B171 | Wrought plate or bar alternative |
| UNS C83600 | Leaded red brass / gunmetal | Cast: ASTM B62 / B584 | Water and valve-side test blanks |
| UNS C84400 | Leaded semi-red brass | Cast: ASTM B584 | General valve-composition service |
Stock form and the governing specification depend on grade and size. Mechanical properties are in the data page for each grade.
Dimensions and Sizes
Key dimensions are OD, thickness, bolt circle, hole count and diameter, and the face. There is no bore or hub, so the drawing is short; the controlling dimensions are thickness and face flatness. For the drilling pattern, see the Class 150 reference table on our slip-on flange page.
Dimensions to confirm
SM-DIM-BLI| Dimension | Basis |
|---|---|
| Outside diameter | Class table or drawing |
| Thickness | Per class table or design calculation |
| Bolt circle (PCD) | Class pattern or drawing |
| Bolt holes | Count and diameter per class or drawing |
| Face and finish | FF / RF; MSS SP-6 or customer finish |
| Tapped port (optional) | Size and thread per drawing |
Sizes
Sizes follow the class tables or your drawing, from small blanks to large-diameter closures. Give nominal size, class and facing in the RFQ.
Pressure Classes
Blind flanges are often used as end closures during hydrostatic testing. Test pressure must not exceed the flange rating at the test temperature. Class (150, 300 or other) and alloy are stated on the purchase order; the allowable pressure comes from the governing standard.
Facing Options
Flat face and raised face are both available. For ring-type or special gaskets, groove or recess dimensions are machined to your drawing.
Applications
- Pipeline isolation and line-end blanking
- Hydrostatic and leak-test closures
- Valve and nozzle isolation
- Spare or future-extension connections
Manufacturing
Discs are produced from cast blanks, continuous-cast bar or wrought plate depending on grade and size. Faces are turned flat, the OD is finished, and the bolt circle is drilled. Faces are checked for flatness before release.
Inspection and Documentation
Visual examination of the gasket face for porosity or surface defects, dimensional checks on OD, thickness, PCD and hole pattern, and material verification with MTC where required. Liquid penetrant or radiographic examination and pressure testing are done only when specified on the purchase order.
Custom Requirements
Special thickness, tapped ports, recessed faces, lifting holes, customer marking and non-standard drilling.
Blind Flanges: common questions
What are bronze blind flanges used for?
They close the end of a pipe, nozzle or valve opening. Typical uses are line isolation, hydrostatic test closures and spare or future connections.
Can a blind flange have a tapped port?
Yes. A drilled and tapped port for a gauge or vent can be machined to your drawing.
Which grade suits seawater blind flanges?
C95800 and C95500 are the common nickel aluminium bronze choices for seawater end closures, subject to the project specification.
Related Information
Have a Drawing or Flange Specification?
Send your drawing, material grade, dimensions and quantity to our technical sales team.