Blind Flange Carbon Steel — Factory Direct Supplier | Huaxia-Steel

A blind flange is a solid circular plate with bolt holes that is used to seal the end of a pipe, valve or pressure vessel nozzle. Unlike other flange types, the blind flange has no centre bore — it completely blocks flow, allowing for inspection, cleaning, pressure testing or future expansion of the piping system. Blind flanges are among the most commonly specified flanges in carbon steel piping systems and are manufactured to ASME B16.5, ASME B16.47 and DIN standards. Huaxia-Steel produces blind flanges in carbon steel from forged blanks for superior pressure integrity.

Product Specifications

Parameter	Specification
Standard	ASME B16.5, ASME B16.47 (Series A & B), DIN 2527, EN 1092-1
Material	ASTM A105 (forged carbon steel)
Size range	1/2″ to 60″ (DN15 to DN1500)
Pressure class	Class 150, 300, 600, 900, 1500, 2500
Face type	Flat Face (FF), Raised Face (RF), Ring Type Joint (RTJ)
Manufacturing method	Forged (A105) or fabricated (A516 plate)
Surface finish	Painted, black, galvanised or machined bare

Available Grades

Grade	Standard	Service
ASTM A105	ASME	Forged carbon steel for general service
ASTM A350 LF2	ASME	Low-temperature forged steel to -46°C
ASTM A516 Gr.70	ASME	Fabricated blind from pressure vessel plate
Q235 / Q345	GB	Chinese standard blind flanges

Dimensional Reference (ASME B16.5, Raised Face)

NPS	Class 150 (mm)	Class 300 (mm)	Class 600 (mm)
2″	OD: 152, Thickness: 19	OD: 165, Thickness: 22	OD: 165, Thickness: 25
4″	OD: 229, Thickness: 24	OD: 254, Thickness: 32	OD: 254, Thickness: 38
6″	OD: 279, Thickness: 26	OD: 318, Thickness: 36	OD: 318, Thickness: 41
8″	OD: 343, Thickness: 29	OD: 381, Thickness: 41	OD: 381, Thickness: 48
12″	OD: 483, Thickness: 32	OD: 521, Thickness: 48	OD: 521, Thickness: 56

Manufacturing Standards

• ASME B16.5 — Pipe flanges and flanged fittings, NPS 1/2″ through NPS 24″.
• ASME B16.47 — Large-diameter steel flanges (Series A MSS, Series B API), NPS 26″ through NPS 60″.
• DIN 2527 / EN 1092-1 — European standard for blind flanges.
• ASTM A105 / A350 — Forging standards for carbon and low-alloy steel flanges.

Applications

• Pipe end closures — permanent or temporary sealing of pipe ends for pressure testing.
• Inspection access points — blind flanges allow easy removal for internal inspection or cleaning.
• Future expansion blanks — seal unused nozzle connections until tie-ins are required.
• Pressure vessel nozzles — blind flanges on vessel inspection openings and manways.
• Isolation points — positive isolation of piping sections during maintenance.

Quality Assurance

• Forged blanks from certified A105 material with traceable heat numbers.
• 100% dimensional inspection of bolt circle, bolt holes and flange face.
• Hardness test (HBW) per ASTM A105 specification.
• RTJ groove dimensional verification with radius gauges.
• EN 10204 3.1 / 3.2 mill test certificates with every shipment.
• Optional third-party inspection by SGS, BV or Intertek.

Packaging and Shipping

• Flanges packed on wooden pallets with rust-preventive oil and VCI paper.
• Each flange marked with: size, pressure class, material grade, heat number and standard.
• Fumigated wooden packaging (ISPM-15) for export shipments.
• Container loading: 10 – 20 MT per 20′ container depending on size and class.

Get a Quote on Blind Flanges

Huaxia-Steel supplies forged carbon steel blind flanges (A105) in sizes 1/2″ to 60″, pressure classes 150 through 2500, with RF, FF or RTJ faces. We provide full EN 10204 3.1 / 3.2 MTC and support third-party inspection. Custom dimensions and non-standard drill patterns are available on request. Contact us for a factory-direct quote.

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