Weld Neck, Slip-On, Blind, Socket Weld, Threaded, Lap Joint
Industry Standard Compliance
Disassembly for Repair & Service
Reliable Gasket Sealing
A pipe flange is a plate or ring used to connect pipes, valves, and other piping equipment to form a piping system through bolted connections and gaskets.
Flanges provide reliable connections between pipes, valves, and equipment using bolted joints with gaskets for leak-free performance.
Allows for easy disassembly and separation for repair, inspection, and regular maintenance without cutting pipes.
Pipe Flanges are circular fittings used to connect pipes, valves, pumps, and other equipment in industrial piping systems, offering robust and leak-proof joints. Manufactured to standards like ASME B16.5, ASME B16.47, and DIN 2632-2638, they are available in materials such as carbon steel, stainless steel, and alloy steel, catering to diverse applications.
These Industrial Pipe Fittings are typically welded or screwed onto pipes, featuring bolt holes for secure assembly. Available in types like weld neck, slip-on, blind, and socket weld flanges, they range from 1/2” to 60” in diameter and handle pressures from 150 to 2500 PSI. Their design ensures easy maintenance and modification of piping systems.
Pipe Flanges undergo rigorous testing, including hydrostatic, ultrasonic, and dimensional checks, to meet industry standards. Coated with anti-corrosion treatments like galvanizing or FBE, they resist rust and chemical attack, supporting temperatures from -20°C to 600°C depending on material. Their versatility makes them suitable for high-pressure and high-temperature environments.
Compared to threaded or welded joints, Pipe Flanges provide superior strength and accessibility, allowing for disassembly without cutting pipes. Proper alignment and torque during installation are critical to ensure leak-proof performance. With a service life of 20–40 years, they are a cost-effective solution for long-term piping needs.
Pipe Flanges address challenges like leaks, misalignment, and corrosion in industrial pipelines, delivering reliable, durable, and adaptable solutions for oil and gas, water treatment, and chemical processing industries.
A bolted flange connection is a complex combination of many factors (Flange, Bolts, Gaskets, Process, Temperature, Pressure, Medium).
All these various elements are interrelated and depend upon one another to achieve a successful result.
The reliability of the flanged joint depends critically upon competent control of the joint making process.
The types divided the flanges in three groups: loose, integral and optional. Below I’ll describe these types according to the Code.
These flanges have no direct connection to the nozzle neck, vessel, or pipe wall. Their attachment method does not provide the mechanical strength equivalent to integral designs.
These flanges are cast or forged integrally with the nozzle neck, vessel, or pipe wall. They may also be butt welded or attached by arc/gas welding, acting as an integral structure.
These flanges act as a unit assembly with the nozzle, vessel, or pipe wall.
They may be calculated as integral, but designers may treat them as loose type if limits are not exceeded:
g0 = 5/8" (16 mm), B/g0 = 300, P = 300 psi, T ≤ 700°F (370°C).
There are many ways to connect flanges, including threading, welding or bolting. The threaded flange is best for low pressure or smaller pipelines because it can maintain its seal. When your pipeline is larger or high pressure, then the welded flange is preferable. A boiler room is one place where welded blind flanges might be used, due to the high pressure involved.
Flanged joints: flanges, bolts and nuts and gaskets
A flange is a external rib at the end of pipes, valves and other flow devices to assemble them.
Dimensions of the flanges are up to specific Standards : DIN, ANSI, AS, BS, JIS
A flanged connection requires two flanges (the “main” and the “companion”), a set of bolts and nuts (whose number depends on the flange diameter and class) and two sealing gaskets. Flanged connections have to be executed and supervised by trained personnel, as the quality of the joint has a critical impact on the performance of the piping system / pipeline (the standard TSE – TS EN 1591 Part 1-4, “Flanges and their joints”, defines a number of requirements for the execution of proper flanged connections). Whereas all elements of the joint are critical, experience shows most leaks are originated by the improper installation of the sealing elements, i.e. the gaskets.
The typical pipe to flange connections are welded or threaded. Welded flanges are used for pipelines and piping systems with high pressures and temperatures, and with diameters above 2 inches.
Threaded connections are instead used for installations of smaller diameter and not subject to severe mechanical forces such as expansion, vibration, contraction, oscillation (forces that would crack the threaded joint). In all these critical cases, butt weld connections are recommended.
Explore Pipe Flanges with targeted long-tail keywords for specifications, applications, and connection solutions.
Note: Pipe Flanges meet ASME and DIN standards, ensuring reliable performance. Contact suppliers for detailed specifications.
Pipe Flanges feature flat surfaces perpendicular to the pipe, mechanically joined using bolts, adhesives, collars, or welds to create leak-proof connections, requiring precise sizing and material compatibility per ASME B16.5 standards.
A flanged connection includes Pipe Flanges, gaskets (full-face or ring types), and bolts, all matched in material (e.g., steel or alloys) for secure, leak-proof joints per industry standards.
There are many ways to connect flanges, including threading, welding or bolting. The threaded flange is best for low pressure or smaller pipelines because it can maintain its seal. When your pipeline is larger or high pressure, then the welded flange is preferable. A boiler room is one place where welded blind flanges might be used, due to the high pressure involved.
A flange is a external rib at the end of pipes, valves and other flow devices to assemble them.
Dimensions of the flanges are up to specific Standards : DIN, ANSI, AS, BS, JIS
A flanged connection requires two flanges (the “main” and the “companion”), a set of bolts and nuts (whose number depends on the flange diameter and class) and two sealing gaskets.
Flanged connections have to be executed and supervised by trained personnel, as the quality of the joint has a critical impact on the performance of the piping system / pipeline (the standard TSE – TS EN 1591 Part 1-4, “Flanges and their joints”, defines a number of requirements for the execution of proper flanged connections). Whereas all elements of the joint are critical, experience shows most leaks are originated by the improper installation of the sealing elements, i.e. the gaskets.
The typical pipe to flange connections are welded or threaded. Welded flanges are used for pipelines and piping systems with high pressures and temperatures, and with diameters above 2 inches.
Threaded connections are instead used for installations of smaller diameter and not subject to severe mechanical forces such as expansion, vibration, contraction, oscillation (forces that would crack the threaded joint). In all these critical cases, butt weld connections are recommended.
Pipe Flange inspection checks outer/inner diameter, bolt circle, bolt hole diameter, hub diameter/thickness, hub length, and bolt hole alignment, adhering to ASME B16.5/B16.47 tolerances.
Pipe Flanges follow standards like ASTM A105 (carbon steel), ASTM A182 (alloy steel), ANSI B16.5, DIN 2632-2638, ASME B16.47, and BS 4504, chosen based on application and environmental needs.
The choice of flange material standard will depend on various factors such as the application, the environment, the fluid being transported, and the required performance characteristics. For example, high-pressure applications may require flanges made from materials with high strength and durability, while corrosive environments may require flanges made from materials with good resistance to corrosion.
The most common type, featuring a raised sealing surface that concentrates the bolting force on a smaller area.
Has a flat sealing surface, commonly used with cast iron flanges and for low-pressure applications.
Features a groove for metal ring gaskets (oval or octagonal), providing metal-to-metal sealing.
Features matching tongue and groove surfaces, providing self-alignment and confined gasket area.
Flange faces have to be smooth enough to ensure a tight, leak-free seal for bolted flanges.
| 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 |
| 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 |
Most commonly used, forged with machined surfaces
Corrosion resistant, grades 304, 316, etc.
High-temperature and high-pressure applications
Cast iron, aluminum, brass, bronze, plastic
| 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.
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.
Metal flanges are classified from 150 to 2500 # rating for different pressure applications.
Special Flanges
Additionally, the flanges can be modified to form other types, depending on application and functions.
These unique designs are made to incorporate specific needs and applications, like reducing flanges to answer to size and orifice flanges to incorporate orifice mounting.
Incoloy 825 Flange
Industries Using
The basic application of the Flange to connect pumps, pipes, valves, and other equipment, often using butt welds, to make a pipework system.
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