Everything You Need to Know About Threaded…

Threaded flanges are an important type of pipe flange used in various industries for connecting pipes, valves, and other equipment without the need for welding. Their design allows for a secure, leak-resistant joint by using internal threads that match the external threads of the pipe. This makes them especially valuable in systems where welding is impractical or undesirable due to safety, material, or operational constraints.

In this article, we will cover what threaded flanges are, their benefits, applications, materials, pressure ratings, installation best practices, and how they compare with other flange types.

What is a Threaded Flange?

A threaded flange, also known as a screwed flange, is a type of flange with an internal thread. This thread matches the external thread of the connecting pipe, enabling the two components to be joined without welding.

Key characteristics:

Available in sizes typically from NPS 1/2″ to NPS 24″.
Designed according to standards like ASME B16.5.
Suitable for low-pressure and non-cyclic service conditions.
Easy to assemble and disassemble.

Advantages of Threaded Flanges

1. No Welding Required

Ideal for applications where welding is risky, such as explosive environments.
Prevents heat-related damage to pipe material.

2. Ease of Installation

Can be installed quickly with basic tools.
No need for specialized welding equipment or personnel.

3. Reusability

Can be removed and reused without damage, reducing replacement costs.

4. Minimal Heat Distortion

Since no welding is involved, there is no risk of heat-induced warping.

5. Versatility

Works well with galvanized, brass, or other materials sensitive to welding.

Limitations of Threaded Flanges

While threaded flanges offer many benefits, they have limitations:

Not ideal for high-pressure, high-temperature, or cyclic load applications.
Threads may become worn or damaged over time.
More prone to leakage compared to welded connections if not properly installed.

Common Applications of Threaded Flanges

Small-Diameter Piping Systems
- Ideal for pipe sizes typically less than NPS 2.
Hazardous Environments
- Used where welding could create a fire or explosion risk.
Temporary Installations
- Easily removable for system changes or maintenance.
Utility Piping
- Often used in water, air, and non-hazardous fluid systems.
Marine and Offshore
- Suitable for low-pressure seawater systems.

Threaded Flange Design Features

Bore with Internal Threads – Matches external threads of the pipe.
Raised Face (RF) or Flat Face (FF) – Common facing options.
Bolt Holes on Flange Rim – For secure connection to mating flanges.
Standard Pressure Ratings – Commonly Class 150 and Class 300.

Materials for Threaded Flanges

Threaded flanges are available in a wide range of materials to meet specific application needs:

Material Type	Advantages	Common Applications
Carbon Steel	Cost-effective, good strength	General industrial
Stainless Steel	Corrosion resistance, hygienic	Food, chemical
Alloy Steel	High strength and heat resistance	High-temp service
Brass/Bronze	Excellent for water and non-corrosive applications	Marine, plumbing
Nickel Alloys	Excellent chemical resistance	Chemical plants

Pressure-Temperature Ratings

Threaded flanges are typically used in lower pressure classes:

Class 150: General service, up to ~285 psi at 100°F.
Class 300: Higher pressure capacity, up to ~740 psi at 100°F.

For high-pressure applications, other flange types like weld neck or socket weld are preferred.

Installation Best Practices

Thread Matching
- Ensure pipe and flange threads are compatible (NPT or BSP standards).
Thread Sealant
- Use PTFE tape or pipe dope for leak prevention.
Alignment
- Properly align to prevent stress on threads.
Torque
- Avoid over-tightening to prevent cracking or distortion.
Inspection
- Check threads for wear or damage before installation.

Threaded Flange vs. Other Flange Types

Feature	Threaded Flange	Weld Neck Flange	Slip-On Flange
Welding Required	No	Yes	Yes
Pressure Rating	Low to Medium	Medium to High	Low to Medium
Installation	Easy, quick	More complex	Moderate
Reusability	High	Low	Low

Standards for Threaded Flanges

ASME B16.5 – Most common for sizes up to NPS 24.
BS 4504 / EN 1092-1 – European standards for metric dimensions.
JIS B2220 – Japanese standards for threaded flange dimensions.

Industries That Use Threaded Flanges

Oil & Gas (low-pressure lines, temporary connections)
Water Treatment
Food Processing
HVAC Systems
Marine Applications

Why Quality Matters in Threaded Flanges

The performance of threaded flanges heavily depends on manufacturing precision and material quality. Working with a trusted supplier like sasaflange ensures:

Dimensional accuracy for leak-free connections.
Compliance with ASME and international standards.
High-quality threading for long service life.
Availability in multiple materials and sizes.

Maintenance Tips for Threaded Flanges

Regular Inspection: Look for thread wear or damage.
Proper Sealing: Always use thread sealants to avoid leakage.
Avoid Over-Torquing: Prevents cracking of the flange hub.
Clean Threads: Remove dirt, oil, or old sealant before installation.

Conclusion

Threaded flanges offer a convenient, cost-effective, and welding-free solution for connecting piping systems, especially in low-pressure and hazardous environments. Their reusability, ease of installation, and compatibility with various materials make them an excellent choice for specific applications in construction, industrial, and marine sectors.

By sourcing from a reputable supplier like sasaflange, you can ensure your threaded flanges meet the highest quality standards, providing reliable and long-lasting performance for your projects.