Blind Flange Manufacturer, Supplier & Exporter
A blind flange (BLF) is a solid flange with no bore, bolted to a mating flange to close the end of a pipeline, a valve or a vessel nozzle. Raaj Fittings manufactures and exports blind flanges in stainless steel, duplex and super duplex, nickel alloys, carbon steel and alloy steel to ASME B16.5, ASME B16.47, EN 1092-1 and other international standards.
Blind flanges are used wherever a line must be closed but may need to be reopened later — at the end of a header left for future extension, on manways and inspection openings, or to isolate a section of piping for pressure testing. Because the flange carries the full line pressure across its face, it is one of the most highly stressed flange types and is made thicker than other flanges of the same class.
All blind flanges are supplied with EN 10204 3.1 mill test certificates, with 3.2 certification and third-party inspection on request.
We export blind flanges to EPC contractors, refineries and stockists across the Middle East and GCC, Europe and the Americas, made to the ASME, EN or DIN standard your project specifies, with PED-compliant supply for European projects on request.
Blind Flange Specifications
½" NPS to 24" NPS to ASME B16.5; 26" NPS to 60" NPS to ASME B16.47 Series A and Series B
Drilled and tapped (NPT / BSP) centre connection for vents, drains or instruments; lifting lugs on large sizes
Forged or cut from plate as permitted by the standard, then CNC machined
EN 10204 3.1 mill test certificate as standard; EN 10204 3.2 on request
Materials & Grades
We supply blind flanges in the following materials and grades. All grades are supplied with EN 10204 3.1 / 3.2 Mill Test Certificates.
Stainless Steel Blind Flanges
Stainless steel flanges offer excellent corrosion resistance and are essential in chemical, pharmaceutical, food processing, and marine environments.
(ASTM A182 F304 / F304L) General corrosion resistance
(ASTM A182 F316 / F316L) Superior resistance to chlorides, acids; marine & pharmaceutical service
(ASTM A182 F316H) High-temperature elevated creep strength
(ASTM A182 F321) Titanium-stabilized; suitable for sustained elevated temperatures
(ASTM A182 F347) Columbium-stabilized; used in heat exchangers and high-temperature piping
High alloy; exceptional resistance to strong acids
Duplex & Super Duplex Stainless Steel Blind Flanges
Duplex and super duplex grades offer approximately twice the yield strength of standard austenitic stainless steel, combined with excellent resistance to stress corrosion cracking and pitting — making them ideal for offshore, subsea, and chemical processing.
(UNS S31803 / S32205) Used in offshore platforms and chemical processing plants
(UNS S32750) Ideal for seawater handling and desalination systems
(UNS S32760) Designed for high-chloride offshore service applications
Nickel Alloy Blind Flanges
For the most aggressive corrosive environments — including concentrated acids, caustic solutions, sour gas service, and extreme temperatures — we offer flanges in a full range of nickel alloys.
(UNS N06600) High-temperature oxidation resistance
(UNS N06625) Outstanding corrosion resistance for offshore and subsea service
(UNS N08825) Excellent resistance to phosphoric and sulfuric acids
(UNS N10276) Broad-spectrum corrosion resistance in acids and chlorides
(UNS N06022) Superior resistance to oxidizing acids
(UNS N04400) Suitable for seawater, hydrofluoric acid, and marine environments
(UNS N08020) Engineered for sulfuric acid service
Exceptional corrosion resistance with low weight
(C70600 / C71500) Preferred for marine and seawater piping systems
Carbon Steel Blind Flanges
Carbon steel is the standard choice for general-purpose, non-corrosive, and elevated-temperature services. The primary grade for forged carbon steel flanges is ASTM A105, and for low-temperature service, ASTM A350 LF2.
Primary grade for forged carbon steel fittings and flanges — covers ambient and elevated-temperature service in pressurised piping systems.
Low-temperature carbon steel, impact-tested for service down to -46°C (-50°F) — LNG, cold climate, and cryogenic piping applications.
Alloy Steel Blind Flanges
Alloy steel flanges are specified for high-temperature, high-pressure service in power generation, petrochemical, and refinery applications.
(5% Cr, ½% Mo) Designed for elevated temperature refinery service
(9% Cr, 1% Mo) Suitable for high-temperature steam and hydrogen service
(1¼% Cr, ½% Mo) Widely used in thermal power plant piping systems
(2¼% Cr, 1% Mo) Used in high-temperature pressure vessels and reactors
(9% Cr, 1% Mo, V, Nb) Engineered for ultra-high-temperature power plant steam lines
What a Blind Flange Does
A blind flange has the same outside diameter, bolt circle and facing as the flange it mates with, but no bore. Bolted against a weld neck or slip on flange, it turns an open end into a pressure-tight closure that can be removed at any time simply by unbolting it.
- Line termination — closes the end of a header or a branch left for future connection.
- Access openings — covers manways and inspection nozzles on vessels, tanks and filters.
- Pressure testing — closes off sections of piping during hydrostatic testing.
- Valve and equipment isolation — blanks off a spool or nozzle while equipment is removed.
Why Blind Flanges Are Thicker
A blind flange carries line pressure over its whole face as well as the bolt load, so the bending stress is higher than in a flange with a bore. ASME B16.5 and B16.47 therefore specify a thickness for each size and class that resists this load. In high-pressure classes the blind is often the heaviest component in the joint, and large sizes are supplied with tapped holes for lifting eyes.
Blind Flange, Spectacle Blind or Paddle Blind?
A blind flange closes the open end of a line. Where a line must be isolated in the middle — between two flanges — a spectacle blind or a paddle blind and ring spacer to ASME B16.48 is used instead.
Applications & Industries
- Header ends and future tie-in points in refineries and petrochemical plants
- Manways and inspection nozzles on pressure vessels, columns and storage tanks
- Hydrostatic test closures for pipelines and process systems
- Pig launcher and receiver closures in oil and gas pipelines
- Offshore and seawater systems in duplex, super duplex and nickel alloys
- Power plant steam and feedwater systems in alloy steel
- Water treatment, desalination and pumping stations
See all flange types we manufacture.
Testing, Inspection, Marking & Packing
Every blind flange is produced under our quality assurance process:
- Incoming material verification with PMI testing
- Chemical and mechanical testing to the applicable ASTM material specification
- Heat treatment as required by the grade, with pickling and passivation for stainless steels
- Dimensional inspection of thickness, outside diameter, bolt circle and facing finish
- Marking with grade, size, pressure class, standard and heat number
Blind flanges are supplied with EN 10204 3.1 mill test certificates; EN 10204 3.2 certificates, third-party inspection and NACE MR0175 / ISO 15156 compliant material are available on request.
Flanges are packed for export with gasket faces protected by covers, rust-preventive coating on carbon and alloy steel, and seaworthy wooden cases; marking, tagging and packing to your specification are available on request.
Why Choose Raaj Fittings for Blind Flanges?
Raaj Sagar Steels has supplied piping components since 2003 and today manufactures flanges at two plants in India for buyers in the Middle East, Europe and the Americas.
- Manufactured in-house — Blind flanges are made in our own plants, so material, dimensions and delivery stay under our control.
- Ready stock, short lead times — common sizes and grades are held in stock for prompt dispatch; other sizes, grades and specials are manufactured to order.
- Certified quality — ISO 9001:2015, ISO 14001:2015 and ISO 45001:2018 certified; PED 2014/68/EU and IBR supply available, and NACE MR0175 / ISO 15156 material on request.
- 100% material verification — PMI testing on incoming material and EN 10204 3.1 mill test certificates with every order; 3.2 certificates on request.
- Third-party inspection ready — we regularly work with SGS, Bureau Veritas, TÜV and DNV.
- Export documentation — MTCs, certificates of origin, packing lists and inspection reports to suit projects in the GCC, Europe and the Americas.
- Export packing — seaworthy packing with end and face protection, and packing to your specification on request.
- Fast response — our team replies to enquiries within one business day.
Blind Flanges — FAQs
A blind flange closes the end of a pipeline, valve or vessel nozzle. It is used at header ends and future tie-in points, on manways and inspection openings, and to close off sections of piping during pressure testing.
A blind flange carries the full line pressure across its face in addition to the bolt load, so it is subject to higher bending stress than a flange with a bore. The thickness given in ASME B16.5 and B16.47 for each size and class allows for this.
Yes. Blind flanges can be supplied with a tapped centre hole (NPT or BSP) for a vent, drain, pressure gauge or other instrument connection. Give the thread size and type when ordering.
We supply blind flanges from ½" to 24" NPS to ASME B16.5 in Class 150 to 2500, from 26" to 60" NPS to ASME B16.47 Series A and B, and to EN 1092-1, DIN, BS, JIS and IS standards.
A blind flange bolts to the end of a line to close it. A spectacle blind is clamped between two flanges in the middle of a line and can be turned to either close (blind side) or open (spacer side) the line, in accordance with ASME B16.48.
Yes. We supply blind flanges for projects under the European Pressure Equipment Directive (PED 2014/68/EU), and with IBR certification for Indian boiler applications. NACE MR0175 / ISO 15156 compliant material is also available on request for sour service in the Middle East and the Americas.
