The connection method between valves and pipelines is crucial as it directly affects whether media leakage occurs. Below are six common connection methods:
01、Flanged Connection
Flanged connection involves flanges at both ends of the valve body, which correspond to the flanges on the pipeline. They are fastened together using bolts and nuts, with a gasket placed in between to achieve sealing. The flange face types include flat face, raised face, male-female face, and tongue-and-groove face, among others, to accommodate different pressure and sealing requirements. This is the most common and versatile connection method in industrial pipeline systems.
Flanged connections are primarily used in main pipeline systems across almost all industrial fields, including petroleum, chemical, power, water treatment, and pharmaceuticals.
02、Welded Connection
The valve ports and pipelines are directly fused together through welding, providing a permanent connection. Welded connections include butt weld connections and socket weld connections.
Welded connections are mainly used in high-temperature and high-pressure steam systems, pipelines conveying flammable, explosive, highly toxic, or highly corrosive media, long-distance pipelines (such as those for oil and natural gas), nuclear power plants, and other applications where high sealing and reliability are required. Among these, socket welding is primarily used for small-diameter pipelines (DN ≤ 50), while butt welding is suitable for pipelines of all diameters.
03、Clamp Connection
The valve ports and pipeline ends feature convex edges or grooves, which are tightly clamped together using a U-shaped or annular clamp (usually equipped with a sealing gasket) to achieve connection and sealing.
Clamp connections are primarily used in industries with high hygiene requirements, such as food, beverages, dairy, biopharmaceuticals, and cosmetics.
04、Threaded Connection
The valve and pipeline are directly screwed together using internal/external threads.
Threaded connections are mainly used in small-diameter pipelines for medium- and low-pressure systems conveying water, gas, oil, etc. They are commonly found in instrument valves and household/building pipelines.
05、Ferrule Connection
Primarily used for small-diameter instrument pipelines, typically with a diameter ≤ DN25. By tightening the nut, the ferrule is deformed, simultaneously compressing the outer wall of the pipeline and the inner conical surface of the valve (or fitting) to achieve sealing and fastening.
Ferrule connections are mainly used in small pipelines such as instrument impulse lines and pneumatic signal lines.
06、Wafer Connection
The valve itself has no flanged or threaded ports and is designed in a thin, pancake-like shape (such as butterfly valves and some check valves). The valve is "clamped" between two pipeline flanges and fastened together with long bolts that pass through the flanges and the valve body.
Wafer connections are mainly used in space-constrained applications and pipeline systems where butterfly valves are widely used, such as in water treatment and low-pressure gas systems.
In summary: Flanged connections dominate due to their versatility and reliability; welded connections are essential for high-temperature, high-pressure, and critical applications; threaded and ferrule connections are common in small-diameter instrument pipelines; clamp connections are the preferred choice in the sanitary industry; and wafer connections are a common solution for butterfly valves in space-constrained situations.
