Flange type expansion butterfly valve

Scope of application

Flanged expansion butterfly valves are suitable for various industrial fields and different types of pipelines. They are applicable to food, pharmaceutical, chemical, petroleum, power, light textile, paper – making and other water supply and drainage, gas pipelines with a temperature ≤ 80°C (the applicable temperature of some products is below 120°C, and the applicable temperature of some metal hard – seal products can reach 425°C) and a nominal pressure ≤ 1.6MPa. They can be used for regulating the flow and intercepting the medium on these pipelines. They can also be applied to the pipelines for transporting various corrosive and non – corrosive fluid media in engineering systems such as the cooling water systems of thermal power plants, urban heating, gas generators, coal gas, natural gas, liquefied petroleum gas, city gas, hot and cold air, chemical smelting, and power generation environmental protection.

Working principle

It is a type of valve that uses a circular butterfly plate as the opening and closing element and rotates with the valve stem to open, close, and regulate the fluid passage. The butterfly plate is installed in the diameter direction of the pipeline. Inside the cylindrical passage of the valve body, the disc-shaped butterfly plate rotates around the axis, with a rotation angle between 0° and 90°. When it rotates to 90°, the valve is fully open.

Product type

According to the connection method.

There are three commonly used types: wafer butterfly valves, flanged butterfly valves, and butt-welded butterfly valves. For a wafer butterfly valve, stud bolts are used to connect the valve between the flanges of two pipes; a flanged butterfly valve has flanges on the valve, and bolts are used to connect the flanges at both ends of the valve to the pipe flanges; the two end faces of a butt-welded butterfly valve are welded to the pipes.

According to product features

• Ordinary type: When selecting, design and install it according to the design specifications of the expansion joint. If limit bolts need to be added, please indicate it during the design. It features multiple functions and a wider scope of application.

• Extended type: Lengthen the expansion joint of the ordinary telescopic butterfly valve so that its length meets the length required by the user (excluding the expansion amount). When renovating an old pipeline, if the valve on the original pipeline needs to be replaced, there is no need to cut and line the connecting part of the valve on the original pipeline, and this extended – type valve can directly replace it. When selecting the extended type, limit measures should also be considered. If limit measures are required, please indicate them during the design.

Product features

Structural and operational characteristics

• It is compact and lightweight, easy to disassemble, assemble and repair, and can be installed at any position.

• Simple and compact structure, small operating torque, and rapid opening with a 90-degree rotation.

• The valve stem has a through-rod structure and is subjected to quenching and tempering treatment, featuring good comprehensive mechanical properties, corrosion resistance, and scratch resistance. When the butterfly valve opens and closes, the valve stem only rotates without moving up and down. The packing of the valve stem is not easily damaged, ensuring reliable sealing. It is fixed to the butterfly plate with a taper pin, and the external extension end is designed to prevent it from being pushed out, so as to avoid the valve stem popping out in case of an accidental breakage at the connection between the valve stem and the butterfly plate.

Performance characteristics

• The flow characteristic tends to be linear, and the regulation performance is good.

• The connection between the butterfly plate and the valve stem adopts a pinless structure, which overcomes the possible internal leakage points.

• The seals are replaceable, and the sealing is reliable, achieving bidirectional sealing.

• The butterfly valve plate can be spray-coated with a cladding layer according to the user’s requirements, such as nylon or PTFE type.

• The valve can be designed with flange connection and wafer connection.

• The driving modes can be selected from manual, electric, pneumatic, worm gear, hydraulic, etc.

Functional features

• It has the function of automatically compensating for the thermal expansion and contraction of pipes, which facilitates loading and unloading. It can not only eliminate the internal force generated by the temperature difference and play a role in expansion and contraction, but also provide convenience for the installation and replacement of maintenance valves.

Product examples

SD341X Turbine Flange-type Telescopic Butterfly Valve

It features a compact structure, easy 90° rotary switch operation, reliable sealing, and a long service life. It is widely applicable to the transportation of liquids and gases (including vapors) in various types of industrial pipelines.

SD941X – SD943H Electric Flange-type Expansion Butterfly Valve

The nominal diameter ranges from DN40 to DN2000. There are two types of valve seat seals: rubber seal and metal hard seal. The nominal pressures include 0.6MPa, 1.0MPa, 1.6MPa, etc. The connection method is flange type. The applicable temperature ranges from -30ºC to +425ºC. The driving methods include manual, worm gear, electric, pneumatic, hydraulic, etc. The valve body materials include cast iron, ductile iron, cast steel, stainless steel, etc. The manufacturing standards include national standard GB, German DIN, American API, ANSI, etc. The applicable media include air, water, steam, gas, oil, etc.

Installation precautions

• It should be placed flat before installation. Do not knock it casually. It is strictly forbidden to remove the bracket during operation.

• The structural length is the shorter length when leaving the factory. During installation, stretch it to the installation length (i.e., the design length).

• When the length between pipes exceeds the installation length of the expansion valve, please adjust the pipe spacing. Do not forcibly pull the expansion butterfly valve to avoid damaging the butterfly valve.