Product Overview
Carbon steel blind flange is a solid forged or plate flange used to close off the end of a pipe, vessel nozzle, or valve. Unlike other flanges, it has no bore; it simply blanks the end to provide a positive seal for hydrostatic testing, inspection, maintenance, or future extension. Because it must withstand the full pressure of the system across its entire area, material quality and dimensional accuracy are critical. Huaxia-Steel supplies carbon steel blind flanges from 1/2″ to 48″ in ASME classes 150 through 2500, to ASTM A105, A105N, A350 LF2, and A694.
Specifications
| Parameter | Range | Standard / Tolerance |
|---|---|---|
| Size | 1/2″ – 48″ (DN15 – DN1200) | ASME B16.5 / B16.47 Series A & B |
| Pressure class | CL150 – CL2500 | Per ASME B16.5 tables |
| Material | A105, A105N, A350 LF2, A694 F52-F65 | ASTM A105 / A350 / A694 |
| Facing | RF, RTJ, FF | ASME B16.5 |
| Thickness | Per ASME B16.5 by size and class | +0.0 / −0.5 mm typical |
| Marking | Size, class, material, heat number, standard | Stamped on OD edge |
Available Grades
| Standard | Grade | Service |
|---|---|---|
| ASTM A105 | A105 / A105N | General pressure service |
| ASTM A350 | LF2, LF3 | Low-temperature service |
| ASTM A694 | F52, F60, F65, F70 | High-strength line pipe |
| EN 1092-1 | P250GH, P245GH | European pressure equipment |
Manufacturing Standards
- Forging: cut from forged billet or forged pancake; normalized for A105N.
- Cutting from plate: common for low-pressure, large-diameter blinds where the code permits; plate must meet the same specification.
- Machining: both faces are finish-turned; bolt holes are drilled on CNC machines to the bolt circle pattern.
- Dimensional control: OD, thickness, bolt circle, hole diameter, and facing per ASME B16.5.
Applications
- Closing pipe ends during construction or modification
- Hydrostatic test blinds for pipelines and vessels
- Isolation blinds for maintenance and shutdown
- Future connection points in piping systems
- Valve and pump nozzles for inspection access
- Pressure vessel manways and handholes
Quality Assurance
- EN 10204 3.1 certificate with heat number traceability
- Chemical and mechanical test reports per ASTM A105
- Dimensional report: OD, thickness, bolt circle, hole size
- Surface finish and hardness check
- Optional NDE (UT/MT/PT) and hydrostatic testing
- Third-party inspection by SGS, BV, TÜV on request
Packaging & Shipping
- Wooden pallets or plywood cases
- Faces separated with cardboard or rubber sheets to prevent damage
- Heat-numbered packing list attached
- Marking preserved and visible on the OD edge
- Container or bulk shipment with tally and photos
Huaxia-Steel supplies carbon steel blind flanges to ASME B16.5 and B16.47, classes 150 – 2500, in A105, A105N, A350 LF2, and A694 grades, RF/RTJ facing. Send us your blind flange list with size, class, material, and facing for a 24-hour factory-direct quotation.
