Metal hard-sealed butterfly valve

The metal hard-sealed butterfly valve is a regulating valve with a simple structure. Its closing part (valve disc or butterfly plate) is a disc, which rotates around the valve shaft to achieve opening and closing. It can be used for on-off control of media in low-pressure pipelines and can also control the flow of various types of fluids such as air, water, steam, various corrosive media, mud, oil products, liquid metals, and radioactive media. The following will introduce the metal hard-sealed butterfly valve to you from multiple aspects:

Application fields

Metal hard-sealed butterfly valves are widely used in the pipeline systems of multiple industrial fields.

• Water conservancy projects and tap water industry: Used to cut off the flow of the medium and ensure the normal operation of the water supply system.

• Power industry: It is used in systems such as power circulating water and can withstand a certain amount of pressure and temperature to ensure the stability of the power production process.

• Petrochemical industry: It can handle various oil products, corrosive media, etc., and adapt to complex working conditions and environments.

• Metallurgical industry: It meets the requirements for fluid control in the metallurgical process and is suitable for pipelines with a medium temperature ≤ 425°C.

• Water supply, drainage and municipal construction: It is used to regulate the flow and cut off the fluid, and is a commonly used valve type in urban infrastructure construction.

Product types and features

Common types

• D342H Horizontal Bidirectional Metal Hard-sealed Butterfly Valve / Double-eccentric Bidirectional Metal-sealed Butterfly Valve: It is mainly used to cut off the medium flow in industrial pipelines of water conservancy projects, tap water, power circulating water, petroleum, chemical industry, etc.

• Clip-on multi-level metal hard-sealed butterfly valve: Its structure is roughly the same as that of an ordinary butterfly valve. The valve stem is driven by a worm gear, and the valve stem drives the butterfly plate to open and close.

• Turbine-driven metal hard-sealed butterfly valve: The valve body and the valve seat are a connected component. The sealing surface layer of the valve seat is overlaid with temperature-resistant and corrosion-resistant alloy materials. The multi-layer soft stacked sealing ring is fixed on the valve plate.

• D343H Three-eccentric Multi-layer Metal Hard-sealed Butterfly Valve: It adopts a three-eccentric hard-sealed structure. There is almost no wear between the valve seat and the butterfly plate, and it has a sealing function that gets tighter as it closes.

Product features

• Good sealing performance: It adopts a triple-eccentric sealing structure. There is almost no wear between the valve seat and the butterfly plate, and it has a sealing function that gets tighter as it closes. The sealing ring is made of stainless steel, which has the dual advantages of metal hard sealing and elastic sealing. It has excellent sealing performance in both low and high temperature conditions, is corrosion-resistant, and has a long service life. The sealing pairs of some products can self-compensate, achieving gas-tight sealing without leakage.

• High durability: The sealing surface of the butterfly plate is overlaid with cobalt-based hard alloy, which is wear-resistant and extends the service life. The large-size butterfly plate adopts a truss structure, featuring high strength, a large flow area, and low flow resistance.

• Flexible installation: It has a two-way sealing function. During installation, it is not restricted by the medium flow direction and is not affected by the spatial position, so it can be installed in any direction; the driving device can be installed at multiple positions (rotated by 90° or 180°), which is convenient for users.

• Excellent operational performance: It adopts a three-dimensional eccentric structure, with almost no friction between the valve seat and the butterfly plate, enabling easy opening and closing. For the pipeline butterfly valves installed horizontally underground, it is equipped with a national synchronous display mechanism, allowing users to observe the closed or open state of the valve from the operating direction.

Selection principles

• In terms of pressure loss: The pressure loss of a butterfly valve is relatively large compared to that of a gate valve and a ball valve. Therefore, it is suitable for pipeline systems where the requirement for pressure loss is not strict.

• Flow regulation requirement: Since the metal hard-sealed butterfly valve can perform flow regulation, it is suitable for selection in pipelines where flow regulation is required.

• Temperature and pressure limits: Due to the limitations of the butterfly valve’s structure and sealing materials, it is not suitable for high – temperature and high – pressure pipeline systems. Generally, the working temperature is below 300°C and the nominal pressure is below PN40.

• Requirements for structural length and caliber: The structural length of a butterfly valve is relatively short, and it can be made into a large caliber. Therefore, in applications where a short structural length is required or for large-caliber valves (e.g., those with a DN of over 1000), butterfly valves are preferably selected.

• Requirement for opening and closing speed: Since a butterfly valve can be opened or closed by simply rotating 90°, it is advisable to choose a butterfly valve in applications where fast opening and closing are required.

Repair technology

In the continuous use of the rubber elastomer in the metal hard-sealed butterfly valve, phenomena such as tearing, wear, aging, perforation and even falling off will occur. The traditional hot vulcanization process is difficult to meet the needs of on-site repair. Special equipment is required for repair, consuming a large amount of heat and electricity, which is time-consuming and laborious. Nowadays, the method of polymer composite materials is gradually used to replace the traditional method. Among them, the Fushi Blue technology system is more widely applied. The adhesion and excellent anti-wear and anti-tearing properties of its products ensure that the service life after repair can reach or even exceed that of new components, greatly shortening the downtime.