5 Common Types of ANSI Flanges in Piping Systems

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Ngày cập nhật: 28 August 2025
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In industrial piping systems, flanges are essential components that connect steel pipes, valves, pumps, and other equipment with secure and leak-proof joints. Flanges not only ensure pressure and temperature resistance but also allow convenient assembly, disassembly, inspection, and maintenance.

Among various flange standards, ANSI flanges are widely used across the globe due to their consistency, safety, and reliability. Developed by the American National Standards Institute (ANSI), the most recognized reference is ANSI B16.5, which specifies dimensions, tolerances, materials, and pressure ratings for flanges ranging from ½ inch to 24 inches.

This article explores the five most common types of ANSI flanges, their characteristics, and applications in industrial piping.


1. What Are ANSI Flanges?

ANSI flanges are designed and manufactured according to ANSI standards. They define critical parameters to ensure interchangeability and performance.

Key features of ANSI flanges include:

  • Standardized dimensions for easy replacement and assembly.

  • Pressure-temperature ratings from Class 150 to Class 2500.

  • Available in carbon steel, stainless steel, alloy steel, and nickel alloys.

  • Globally recognized in multiple industries for reliability and safety.


2. The Role of Flanges in Piping Systems

Flanges play vital roles in piping networks:

  • Connection: Join pipes or equipment together.

  • Flexibility: Enable quick disassembly for cleaning or replacement.

  • Maintenance: Allow inspection and modifications without cutting pipes.

  • Sealing: With gaskets and bolts, ensure leak-proof performance.

Choosing the correct flange type depends on pressure, temperature, and service conditions.


3. Five Common Types of ANSI Flanges

a) Weld Neck Flanges

  • Designed with a long tapered hub for smooth stress distribution.

  • Attached by full penetration butt welds, ensuring strong connection.

  • Smooth bore alignment minimizes turbulence and erosion.

  • Suitable for high-pressure and high-temperature systems.

b) Slip-On Flanges

  • Installed by sliding over the pipe and welding inside and outside.

  • Simple structure, low cost, and easy alignment.

  • Typically used for low to medium-pressure applications.

c) Blind Flanges

  • Solid discs without a bore, used to seal the end of a pipe or vessel.

  • Can be removed for inspection or system expansion.

  • Widely applied in pressure testing and system isolation.

d) Socket Weld Flanges

  • Used for small-diameter, high-pressure piping.

  • Pipe is inserted into the socket and welded at the outer fillet.

  • Provide strong mechanical connection and smooth bore alignment.

  • Common in hydraulic and high-pressure steam systems.

e) Threaded Flanges

  • Equipped with internal threads to connect directly without welding.

  • Convenient for low-pressure or non-weldable environments.

  • Reusable after disassembly.

  • Often applied in water supply, gas distribution, or emergency piping.


4. Materials for ANSI Flanges

ANSI flanges are manufactured in different materials to suit operating environments:

  • Carbon Steel: Cost-effective for moderate pressure.

  • Stainless Steel: Corrosion resistance for chemical and marine use.

  • Alloy Steel: Enhanced strength for high-pressure, high-temperature service.

  • Nickel Alloys: Excellent resistance to aggressive chemicals.


5. ANSI Flange Pressure Ratings

ANSI flanges are classified into pressure classes: 150, 300, 600, 900, 1500, and 2500.

  • Class 150: Suitable for low-pressure services such as water.

  • Class 600–900: Applied in refinery and mid-pressure systems.

  • Class 1500–2500: Designed for severe high-pressure and high-temperature conditions.


6. Industrial Applications of ANSI Flanges

ANSI flanges are essential in:

  • Oil & Gas: Pipelines, offshore rigs, refineries.

  • Power Generation: Boilers, turbines, steam piping.

  • Chemical Industry: Process reactors, transport systems.

  • Water Treatment: Distribution and sewage systems.

  • Marine Industry: Shipbuilding and offshore structures.


7. Advantages of ANSI Flanges

  • Standardized design ensures compatibility.

  • Wide range of pressure and temperature capabilities.

  • Easy replacement and maintenance.

  • Reliable leak-proof sealing with proper gaskets and bolts.

  • Recognized as a global piping solution.


Conclusion

ANSI flanges are globally standardized solutions that ensure safety, reliability, and efficiency in piping systems. The five common types – Weld Neck, Slip-On, Blind, Socket Weld, and Threaded – each offer unique advantages for specific service conditions.

At Sunjin Metals Vina (SJM Vina), we specialize in supplying steel pipes, flanges, and fittings imported from Korea, all manufactured to meet international standards. With proven expertise and strong supply capability, we are committed to providing high-quality piping materials for critical industries.


📍 Sunjin Metals Vina (SJM Vina)
Address: 628 Le Hong Phong Street, Ward 10, District 10, Ho Chi Minh City, Vietnam
Hotline: +84 33 4233 127
Email: sjmvina@sunjinmetal.com
Website: www.sjmvina.com.vn

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Sunjin Metals Vina (SJM Vina)

Add: 628 Lê Hồng Phong, Vuon Lai Ward, Ho Chi Minh City, Vietnam

Hotline: +84 33 4233 127

Email: sjmvina@sunjinmetal.com

Tax Code: 0315448500

Website: sjmvina.com.vn

         

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