Flanged Valves vs Threaded Valves

Figure 1: Flanged (left) and threaded valves (right)

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Flanged and threaded valves are two commonly used types of valve fittings in industries. Choosing between them requires careful consideration of pressure, temperature, installation complexity, space constraints, and cost-effectiveness. This article explores and compares both valve types to help the user make an informed decision for an application.

Flanged valves

A flanged valve has flanges at the end of its body. A flange connection joins two materials with either an internal or external lip. A gasket placed between these materials stops leaks. Typically, bolts secure this connection; however, the pieces can sometimes be welded together.

• Flanges are available in various styles, including slip-on flanges, lap-joint flanges, weld-neck flanges, and socket-weld flanges.
• Flanged valves find wide application across diverse industries, including oil and gas, chemical processing, power generation, and water treatment.
• Most flanged valves adhere to industry standards like ANSI/ASME B16.5, DIN -1/ISO , and SAE J518, which specify the dimensions, materials, and technical requirements for flanges used in various industrial applications.
• Flange ratings are typically designated by a numerical value, such as Class 150, Class 300, and Class 600; the higher numbers indicate greater pressure and temperature resistance.

Advantages

• Versatility: Flanged valves are versatile and can be used with different pipe sizes and materials, including steel, cast iron, and PVC. Also, they work well with hazardous fluids.
• Easy to remove: Flanged valves can be easily removed within the system without removing other components, which is difficult with threaded valves due to space constraints.
• Strength and durability: The flanged connection gives extra strength and durability to handle high pressure and temperature.

Limitations

• Cost: Installing flanged valves can be more expensive due to the need for bolt tightening and gasket replacement.
• Size: Flanged connections are typically larger and bulkier than other connections, which may not be ideal for space-constrained applications.

Figure 2: Flanged valves used in an industry

Threaded valves

Threaded valves, or screwed valves, have threaded ends for direct connection to compatible pipes or fittings. Threads are standardized to ensure compatibility and ease of maintenance. Common thread standards are BSP, NP, and UTS. Threaded valves are commonly found in plumbing systems, small-scale industrial processes, and residential applications.

Advantages

• Simplicity: Thread connections are simple and easy to install or replace, requiring no additional tools. Also, threaded connections need not be tightened as there are no bolts.
• Compact: They tend to be more compact and lightweight, making them suitable for tight spaces.
• Cost-effective: Threaded connections cost less as no multiple parts and flange configurations exist.
• Vibration tolerance: Threaded valves tolerate pump vibrations better as the threaded connection provides greater stability and reduces the risk of loosening under mechanical stress.

Limitations

• Limited stress tolerance: Threaded connections may not handle high pressures and temperatures, as well as other connection types.
• Corrosion: The threads in threaded valves are more susceptible to corrosion, making them difficult to remove and potentially weakening the connection.
• Potential leakage: Over time, threaded connections may experience wear or loosening, leading to potential leakage. Proper installation, periodic inspection, and maintenance are necessary to ensure the integrity of threaded valves.

Comparison table

Table 1: Flanged valves vs threaded valves

Parameter Flanged valves Threaded valves Connection method Flanges with bolted joints Threaded ends Application range High-pressure and high-temperature applications Low-pressure and low-temperature applications Installation complexity More complex installation due to alignment and bolting Simple installation by screwing onto compatible threads Maintenance Easy removal and maintenance with bolted flange connections Straightforward maintenance due to threaded connections Space requirement Require more space for flanges and bolting Compact design suitable for space-constrained installations Cost Generally more expensive due to flanges and bolts Cost-effective Leakage risk Provides a tight and reliable seal with proper installation Potential leakage due to wear or loosening of threaded joints Pressure and temperature Suitable for high-pressure and high-temperature conditions Not recommended for demanding pressure and temperature ranges

FAQs

What is the difference between flanged valves and threaded valves?

Flanged valves have a flange connection that requires bolts for installation, while threaded valves have threads that allow for direct screwing onto the pipeline.

Which type of valve is more commonly used in industrial applications, flanged or threaded?

Flanged valves are more commonly used in industrial applications because they can handle higher pressures and larger pipe sizes.

When it comes to industrial valve selection, ball valves with flanged end connections offer a robust solution with some distinct benefits. While threaded and socket weld ends have their place, flanged ball valves rise above for many demanding services and critical applications.

The rugged flanged body design, easy maintenance, and versatility in materials/configurations make these valves a trusted choice across countless facilities. If you’re considering a new ball valve installation, it’s worth exploring if a flanged option is the optimal fit.

Flange Ball Valve – Key Benefits

If you are wondering, “Are flange ball valves better?,” here are some of the key advantages that flanged ball valves can provide over alternative end connections:

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1. Ability to Withstand Higher Pressures 

With their sturdy two-piece body construction, flanged ball valves can handle significantly higher pressure ratings compared to threaded units. The flanges create a blowout-proof design by containing forces within the rigid body assembly.

Some flanged valves achieve pressure ratings above 5,800 psi for harsh, severe-duty applications. High-integrity pressure boundaries are critical for applications like oil/gas production, steam systems, chemical processing plants and more. Flanged connections provide the required safety margins.

2. Full Bore Design for Minimum Flow Restriction 

Flange end ball valve typically features a full-bore design where the inner ball cavity matches the pipe’s inner diameter. This open area allows an unrestricted flow path when open with minimal pressure drop or flow resistance.

Other end connection types may utilize reduced ports, venturi shapes or plugs which can impede flow and increase turbulence. The flanged full-bore configuration is ideal for slurries, high-volume utility services, and applications where head loss needs to be minimized.

3. Simplified Maintenance and Inline Removal 

Perhaps the biggest advantage of flanges is easy valve removal from the pipeline without hot-tapping or line breaks. The bolted end connections enable quick disassembly for maintenance or replacement by simply unbolting the flanges.

This eliminates the need for pipe cutting, threading, re-welding and other invasive & costly procedures. In-line maintainability is a major benefit for critical services, reducing costly downtime. Easy access also simplifies internal inspection, repacking, gasket replacement and part changeouts.

4. Ability to Handle Extreme Temps and Medias 

Flanged construction allows for a wide selection of valve body materials and trims to handle corrosive media and extreme temperatures. Options include carbon steel, stainless, high-nickel alloys, titanium and special metal/lining combinations.

These robust metallurgy choices provide excellent chemical resistance and enable flanged ball valves to operate reliably in the harshest refinery, chemical and slurry applications. The flanged design avoids potential weaknesses from threaded connections in these services.

Conclusion

While there are applications where threaded or socket weld connections are suitable, flanged ball valves provide undeniable advantages for many industrial uses. Their pressure containment, flow characteristics, maintainability and material flexibility make them an excellent choice for critical services.

Specify a flanged ball valve from a trusted manufacturer like Xintai Valve Company. With end connections built to global standards like ANSI, ASME and more, you can ensure long-lasting, reliable performance. 

Don’t compromise your process piping with subpar valves – insist on the safety and quality of Xintai’s flanged offering.