What are the common connection methods for sanitary butterfly valves?

The core design principles of sanitary butterfly valves are seamless connection, easy disassembly, and easy cleaning to meet the stringent hygiene requirements of industries such as food and pharmaceuticals. Below is a detailed comparison of the four most common connection methods, their characteristics, and applicable scenarios:

1. Clamp-on Quick-Connect Type

This is the most common and flexible connection method in food processing plants.

Structure: The valve has chucks (commonly known as quick-connect heads) at both ends, and the valve is secured to the pipeline using clamps, 

gaskets, and nuts.

Advantages:

Extremely quick assembly and disassembly: No special tools are required; the valve can be disassembled simply by rotating the clamp nut, 

facilitating frequent cleaning, inspection, or replacement.

High flexibility: Pipeline layout adjustments are convenient.

Good hygiene: The gasket is compressed by the clamp, resulting in a smooth and flat inner wall, making it less prone to material residue.

Applicable scenarios: Most food, beverage, beer, and pharmaceutical pipelines that require regular disassembly and cleaning.

2. Welded Connection

This is the highest level of hygiene and the most permanent connection method.

Structure: The valve body is directly butt-welded to the pipeline at both ends.

Advantages:

No Leaks: Completely eliminates the risk of seal failure at the connection.

Absolute Hygiene: The inner wall is completely smooth, without any gaps or gaskets, making it the highest level of aseptic connection method,

completely preventing microbial growth.

Disadvantages:

Difficult Disassembly: Replacing the valve requires cutting the pipeline, making maintenance inconvenient.

High Installation Requirements: Requires professional argon arc welders for welding and polishing to ensure a smooth weld.

Applicable Scenarios: Aseptic filling lines, high-purity water systems, permanent pipelines with minimal disassembly, and critical workstations 

with extremely strict aseptic requirements.

3. Threaded Connection

This connection method is relatively rare in sanitary applications, but is still used in certain small-diameter applications.

Structure: The valve has internal or external threads at both ends, which are screwed onto the threaded fittings on the pipeline. Sealing tape or 

sealant is usually applied to the threads.

Advantages:

Easy Installation: No welding required, simply tighten.

Lower Cost: Processing costs may be slightly lower compared to welded and quick-installation types.

Disadvantages:

Possible Hygiene Dead Zones: Threaded gaps are difficult to clean thoroughly, easily trapping dirt and bacteria.

Not Recommended for Main Food Processing Piping: In strict hygiene reviews, threaded connections are generally not accepted for piping that comes into direct contact with food.

Suitable Scenarios: Only for instrument interfaces, vents, sampling ports, or auxiliary piping that does not come into contact with food.

4. Flanged Type: 

Less commonly used in sanitary applications, mostly for large diameters or connection to specific equipment.

Structure: The valve has flanges at both ends, connecting to the pipe flange via bolts and gaskets.

Advantages:

High Strength: Suitable for large diameters or high-pressure conditions.

Easy Disassembly: Disassembly is achieved by unscrewing the bolts.

Disadvantages:

Bulk: Takes up a lot of space and is costly.

Potential blind spots: Improper installation of the gasket may create gaps.

Applicable scenarios: Typically used for DN150 and above, or when direct connection to existing flange equipment (such as tanks, pumps).

Summary and Selection Recommendations