Blind Flange

Blind Flange

High-pressure Sealing Solution For Pipelines

Blind flanges offer reliable end sealing for industrial piping, ensuring pressure containment and corrosion resistance in oil, gas, and chemical systems.

Blind Flange

High-pressure Sealing Solution For Pipelines

Blind flanges offer reliable end sealing for industrial piping, ensuring pressure containment and corrosion resistance in oil, gas, and chemical systems.

Blind Flange
Pipe End Cap
Sealing Flange Solutions
ASME B16.5 Blind Flange

Blind Flange is a solid disc used to seal the end of a piping system, preventing flow and providing pressure containment. Conforming to ASME B16.5, ASME B16.47, and DIN standards, it is crafted from materials like carbon steel, stainless steel, and alloys for durability in harsh conditions.

The Sealing Flange Solution features a flat or raised face with bolt holes for secure attachment, available in sizes from 1/2” to 60” and pressure ratings up to 2500 PSI. Its design allows for easy inspection or future expansion by removing the flange, making it ideal for temporary or permanent closures.

Blind Flange undergoes hydrostatic and ultrasonic testing to ensure leak-proof performance. Coated with galvanizing or FBE for corrosion resistance, it withstands temperatures from -20°C to 600°C, depending on the material, and is suitable for high-pressure applications in oilfields and refineries.

Compared to pipe caps, Blind Flange offers greater accessibility and reusability, enabling system modifications without cutting pipes. Proper bolt torque and gasket selection are key to maintaining its seal integrity. With a service life of 20–40 years, it is a cost-effective closure option.

Blind Flange addresses challenges like pressure leaks and corrosion in industrial piping, providing a reliable, durable, and adaptable solution for sealing oil, gas, and chemical pipelines.

DIN16 Blind Flange

DIN16 Blind Flange

What is a Blind Flange?

Blind flanges are providing a means to seal off the end of a pipe or vessel.

These flanges are typically solid discs bolted onto the pipe’s end, typically with a defined facing for sealing. Blind Flanges are used for many applications, including:

  • Isolation of pipe sections for maintenance or repai
  • Termination of pipelines
  • Pressure testing
  • Access points for cleaning or inspection
DIN16 Blind Flange

1. Blind flange 2. Stud Bolt 3. Gasket 4. Other flange

Major Function - Where to use

The blind flange is used to close ends of piping systems.

It is a kind of round plate with no center hold but with all the proper bolt holes. This blind flange is available in various sizes and materials and is used to provide positive closer on the ends of pipes, valves or equipment nozzles. This flange helps in easy access to a line once it has been sealed. The blind flange is sometimes custom made or machined to accept a nominal sized pipe to which reduction is being made.

A blind flange is useful for making repairs to a pipeline further up the line. In fact, during construction of a pipeline, a blind flange may be built into the final length of pipe. This allows for expansion or continuation of the pipeline simply by adding onto the final flange.

Types of Blind Flanges

Raised Face Blind Flange

Features a raised ring around the face for improved sealing, suitable for high-pressure connections.

  • Strong sealing surface
  • High-pressure applications
  • Industry standard design
Ring Joint Blind Flange

Uses a metal ring gasket for sealing, excellent for extreme pressure and temperature conditions.

  • Metal-to-metal seal
  • High temperature resistance
  • Leak-proof performance
Flat Face Blind Flange

Designed with a flat face, mainly used in low-pressure applications where sealing demands are moderate.

  • Simple structure
  • Low-pressure use
  • Cost-effective option
Weld Neck Blind Flange

Attached by a circular weld around the neck, providing excellent strength and durability under harsh conditions.

  • High-strength connection
  • High-pressure service
  • Long-term durability
Close Nipple Blind Flange

Similar to weld neck design but with a shorter neck, ideal for installations in tight spaces.

  • Compact design
  • Space-saving solution
  • Reliable sealing

Manufacturing Types and Costs

Forging Blind Flange

Forged blind flanges have better mechanical properties, higher strength, and superior resistance to shear and tensile forces.

  • Dense structure & refined grain
  • Better mechanical strength
  • Lower carbon content, less rust
  • High manufacturing cost
  • Improper forging may cause cracks
Casting Blind Flange

Casting blind flanges are more economical to produce, with accurate shapes but inferior mechanical performance.

  • Lower cost production
  • Accurate blank shape, less machining
  • Prone to defects (air holes, cracks, inclusions)
  • Weaker internal streamline
  • Poorer mechanical strength
Cost Ranking: Forging (highest) → Medium Plate Cutting → Casting & Forging → Casting (lowest)
Quality Ranking: Forging ≈ Medium Plate Cutting → Casting & Forging → Casting (lowest)
Forged Blind flange Appication

Forged Blind flange Appication

Applications

What do blind flanges do?

Without a blind flange, it would be next to impossible to repair or perform ongoing maintenance to a pipeline unless the flow was shut off at a earlier valve, which could affect miles of pipeline.

The use of flanged pipe has significantly sped up the process for constructing pipelines. It has also made the task of repair and sectional replacement easier.

A blind flange may be used for isolating a pipe, valve, or pressure vessel. Our flanges are extensively used in the oil, gas and petroleum industries.

Features of Blind Flanges

NPT Fittings

Blind flanges can be supplied with NPT fittings, allowing pressure test connections.

Pipe End Closure

They are commonly used to blank off the ends of pipes, providing complete closure.

Valve & Vessel Closure

Also used to blank off the ends of valves and pressure vessel openings.

High Stress Resistance

Blind flanges are the most highly stressed type, especially in larger sizes, due to internal pressure and bolt loading.

Bending Stress Tolerance

They can safely withstand higher bending stresses at the center compared to other flanges.

Standard Pipe Sizes

Blind flanges are manufactured to fit standard pipe sizes, ensuring wide compatibility.

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Standards and Specifications
  • • Blind Flange specifications
  • • ASME B16.5 blind flange
  • • High-pressure flange standards
  • • Blind flange dimensions
Applications
  • • Blind Flange for oil pipelines
  • • Chemical plant sealing flanges
  • • Power generation blind flanges
  • • Water system pipe closures
Material and Properties
  • • Stainless steel blind flange
  • • Carbon steel flange sealing
  • • Alloy blind flange strength
  • • Corrosion-resistant flanges
Installation and Testing
  • • Blind Flange installation guide
  • • Flange hydrostatic testing
  • • Blind flange sealing process
  • • Pressure testing flanges

Note: Blind Flange meets ASME and DIN standards, ensuring reliable sealing. Contact suppliers for detailed specs.

Flange Face Types

Flange Face
Raised Face (RF)

The most common type, featuring a raised sealing surface that concentrates the bolting force on a smaller area.

Lip Height: 1/16" for 150#-600#, 1/4" for 900# and higher
Flat Face (FF)

Has a flat sealing surface, commonly used with cast iron flanges and for low-pressure applications.

Application: Cast iron flanges, pumps, and valves
Ring Joint (RTJ)

Features a groove for metal ring gaskets (oval or octagonal), providing metal-to-metal sealing.

Material: 316 stainless steel rings for corrosive applications
Tongue & Groove (T&G)

Features matching tongue and groove surfaces, providing self-alignment and confined gasket area.

Benefit: High-pressure applications with good gasket compression

Flange faces have to be smooth enough to ensure a tight, leak-free seal for bolted flanges.

Flange Face Types
Flange Face Type Flange Face Type Flange Face Type
Type A: flat face Type D: groove face Type G: O Ring recess
Type B: raised face Type E: spigot Type H: O Ring groove
Type C: tongue face Type F: recess
Flange Face

Standards & Materials

International Standards
ASME B16.5 Pipe Flanges NPS 1/2 - 24
ASTM A105 Forged Carbon Steel
ASTM A350 LF2 Low-Temperature Service
ASTM A182 High-Temperature Service
ASTM A694 High-Pressure Transmission
DIN EN 1092-1 European Standard PN 2.5-400
Common Materials
Carbon Steel

Most commonly used, forged with machined surfaces

Stainless Steel

Corrosion resistant, grades 304, 316, etc.

Alloy Steel

High-temperature and high-pressure applications

Other Materials

Cast iron, aluminum, brass, bronze, plastic

Material Grades for Piping System Components (ASTM Standards)
Material Category Fittings (ASTM Grade) Flanges (ASTM Grade) Valves (ASTM Grade) Bolts & Nuts (ASTM Grade)
Carbon Steel A234 Gr WPA A105 A216 Gr WCB A193 Gr B7
A194 Gr 2H
A234 Gr WPB A105 A216 Gr WCB
A234 Gr WPC A105 A216 Gr WCB
Carbon Steel Alloy
(High-Temperature)
A234 Gr WP1 A182 Gr F1 A217 Gr WC1 A193 Gr B7
A194 Gr 2H
A234 Gr WP11 A182 Gr F11 A217 Gr WC6
A234 Gr WP12 A182 Gr F12 A217 Gr WC6
A234 Gr WP22 A182 Gr F22 A217 Gr WC9
A234 Gr WP5 A182 Gr F5 A217 Gr C5
A234 Gr WP9 A182 Gr F9 A217 Gr C12
Carbon Steel Alloy
(Low-Temperature)
A420 Gr WPL6 A350 Gr LF2 A352 Gr LCB A320 Gr L7
A194 Gr 7
A420 Gr WPL3 A350 Gr LF3 A352 Gr LC3
Austenitic Stainless Steel A403 Gr WP304 A182 Gr F304 A182 Gr F304 A193 Gr B8
A194 Gr 8
A403 Gr WP316 A182 Gr F316 A182 Gr F316
A403 Gr WP321 A182 Gr F321 A182 Gr F321
A403 Gr WP347 A182 Gr F347 A182 Gr F347

ASTM standards define the specific manufacturing process of the material and determine the exact chemical composition of pipes, fittings and flanges, through percentages of the permitted quantities of carbon, magnesium, nickel, etc., and are indicated by "Grade".

The usual materials of flanges include stainless steel, carbon steel, aluminum and plastic. The choice of the material largely depends on the purpose of the flange. For example, stainless steel is more durable and is necessary for heavy use. On the other hand, plastic is more feasible for use in the home because of its reasonable price and easy installation. The materials used for flanges are under the designation of the American Society of Mechanical Engineers.

Flange materials acc. to ASTM

The most common materials for pipe flanges (forged grades) are: ASTM A105 (carbon steel high temperature to match A53/A106/API 5L pipes), A350 Grades LF1/2/3 (carbon steel low temperature to match A333 pipes), A694 Grades F42 to F80 (high yield carbon steel to match API 5L pipe grades), ASTM A182 Grades F5 to F91 (alloy steel flanges to match A335 pipes), A182 Grade F304/316 (stainless steel flanges to match A312 SS pipes), A182 Gr. F44/F51/F53/F55 (duplex and super duplex to match A790/A928 pipes) and various nickel alloy grades (Inconel, Incoloy, Hastelloy, Monel).

The material qualities for these flanges are defined in the ASTM standards.

Flange By Material

Pressure Classes

Metal flanges are classified from 150 to 2500 # rating for different pressure applications.

150#
300#
600#
900#
1500#
2500#
Blind Flange
Incoloy 825 Flange

Incoloy 825 Flange

Industries Using

Blind Flange Applications

The basic application of the Blind Flange to connect pumps, pipes, valves, and other equipment, often using butt welds, to make a pipework system.

  • Oil and Gas Industry
  • Chemical Industry
  • Power Generation
  • Water Treatment
  • Construction Industry

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