Unveiling the Threaded Flange: A Practical Guide for Everyone

Threaded flanges are an essential component in many piping systems. Commonly used in applications where welding is either unsafe or impractical, threaded flanges provide secure, leak-proof connections. These versatile fittings are crucial in utility services such as air, water, and nitrogen systems, handling pressures up to Class 300.

In this guide, we’ll explore the key features, advantages, and material options for threaded flanges, ensuring you choose the right solution for your industrial needs.

Main Features of a Threaded Flange

A threaded flange is a type of flange that allows pipes to be connected by screwing them together. It is also known as a screwed flange.

This unique design eliminates the need for welding. Such a feature makes a threaded flange an ideal choice for certain applications where welding may not be feasible or safe.

However, threaded flanges are generally limited to smaller pipe sizes. These typically range from 1/2 inch to 4 inches. Most engineering organizations restrict the use of threaded flanges to this size range.

These flanges are often used in utility services, such as instrument air, plant air, nitrogen, potable water, and raw water systems. Threaded pipe flanges can handle pressures up to Class 300 rating. The feature makes them suitable for various low- to medium-pressure applications.

Advantages of a Threaded Pipe Flange

Threaded pipe flanges offer several advantages over other types of flanges. These are the following:

Ease of Installation: The primary advantage of a threaded pipe flange is its ease of installation. Since it doesn’t require welding, it can be quickly screwed onto a pipe. This means a threaded flange saves time and labor. This is particularly advantageous in situations where welding might not be feasible.
Flexibility: Threaded pipe flanges provide flexibility in disassembly and reassembly. They can be easily removed and replaced. This class of flange is ideal for maintenance and repair tasks.
Leak-Proof Seal: When used with appropriate gaskets or sealants, threaded pipe flanges can provide a reliable and leak-proof connection. This is critical in systems where avoiding leaks is essential.

Standards for Threaded Flanges

To ensure threaded flanges’ reliability, compatibility, and safety across industries, they are manufactured and inspected according to several international standards.

ASME B16.5: The Core Standard for Pipe Flanges

The ASME B16.5 standard, developed by the American Society of Mechanical Engineers (ASME), is perhaps the most widely recognized and adopted standard for pipe flanges and flanged fittings. These include threaded flanges.

Key Provisions:

Dimensions: ASME B16.5 provides detailed guidelines on the dimensions of threaded pipe flanges. This ensures uniformity across manufacturers and guarantees interchangeability of parts.
Pressure ratings: The standard covers pressure classes ranging from Class 150 to Class 2500. For threaded pipe flanges, the standard outlines specific pressure ratings to ensure they are suitable for their intended applications.
Materials: ASME B16.5 also specifies acceptable materials for threaded flanges. These typically cover a range of materials from carbon steel to stainless steel.

ANSI B16.1: Cast Iron Pipe Flanges and Flanged Fittings

The ANSI B16.1 standard is developed by the American National Standards Institute (ANSI). It is another important reference for threaded flanges. Threaded pipe flanges that follow this standard are designed for lower-pressure applications. This is compared to those covered by ASME B16.5.

Key Provisions:

Material Specifications: The standard primarily focuses on cast iron as the material for threaded pipe flanges. It is often used in utility services such as water distribution and non-corrosive fluid systems.
Design and Manufacturing: ANSI B16.1 outlines specific design criteria for cast iron threaded flanges.
Inspection and Testing: This standard ensures that cast iron threaded flanges are rigorously inspected and tested for defects. These may include cracks.

DIN Standards: German Industrial Standards for Threaded Flanges

The DIN standards (Deutsches Institut für Normung), widely used in Europe, also provide specifications for threaded flanges. Two relevant standards include DIN 2565 and DIN 2566. These cover dimensions, pressure ratings, and material requirements for threaded pipe flanges.

Key Provisions:

Compatibility with European Systems: DIN standards ensure that threaded flanges are compatible with European piping systems.
Materials: DIN standards cover a broad range of materials, similar to ASME B16.5, including carbon steel and stainless steel. However, there are some material specifications unique to European industries.
Pressure Ratings and Applications: DIN 2565 and DIN 2566 provide specific guidance on the pressure ratings of threaded flanges. This is similar to ASME standards but tailored to European industrial environments.

JIS Standards: Japanese Industrial Standards for Threaded Flanges

The JIS (Japanese Industrial Standards) provides guidelines on the dimensions, materials, and pressure ratings of threaded flanges used in Japan. It is also applicable to other regions that adopt Japanese standards.

Key Provisions:

Material Specifications: JIS standards cover a variety of materials, including carbon steel, stainless steel, and alloy steel. This helps guarantee that threaded flanges are suitable for a wide range of applications.
Design and Dimensions: Like other international standards, JIS B2220 ensures that the dimensions of threaded flanges are consistent. Such a feature makes
Pressure Ratings: them interchangeable with other components in Japanese and international piping systems.

Material Grade for Threaded Flanges

Below are some common material grades used for threaded pipe flanges. Each offers distinct advantages depending on the intended use.

Material Grade	Key Features	Common Applications
Carbon Steel Threaded Flanges: ASTM A105	Strength and DurabilityCost-EffectiveModerate Corrosion Resistant	Water distributionPlant airGeneral utility services
Alloy Steel Threaded Flanges: ASTM A182 F5, F9, F11	High-Temperature ResistantCorrosion ResistantHigh-Pressure Capability	Power generationPetrochemical plantsHigh-temperature and high-pressure systems
Stainless Steel Threaded Flanges: ASTM A182 F304, F316	Exceptional Corrosion ResistanceHygienic PropertiesTemperature and Pressure Resistant	Chemical processingFood and pharmaceuticalsMarine environments
Duplex and Super Duplex Stainless Steel: ASTM A182 F51, F53	High StrengthOutstanding Corrosion ResistantExtended Service Life	Offshore engineeringPetrochemical processingMarine applications (exposure to seawater and chlorides)

Conclusion

Threaded flanges provide an easy-to-install, versatile solution for connecting pipes without welding, ideal for utility services and lower-pressure systems. With material options like carbon steel, alloy steel, stainless steel, and duplex stainless steel, they suit a variety of industrial applications, all backed by strict standards such as ASME and DIN.

For reliable, high-quality threaded flanges, Longan Flange is a trusted manufacturer. The brand offers durable products that meet international standards. Longan has been in the industry since 2011. Their flanges are applied across diverse industries due to their lasting performance.

References

Threaded Flanges Market Size, Share and Growth [2030] (1)

Threaded Flanges Research Papers – Academia.edu (2)