1. Flange connection

Valves are connected to pipes by matching flanges and bolted fasteners for high temperature, high pressure and large diameter piping systems.

Advantages:

Strong connection, good sealing, suitable for valve connection under harsh conditions such as high pressure, high temperature and corrosive media.

Easy to disassemble and repair, easy to maintain and replace valves.

Cons:

The installation requires more bolts and nuts, and the installation and maintenance cost is high.

The flange connection is relatively heavy and occupies a large space.

Flange connection is a common valve connection, its standard mainly includes the following aspects:

Flange type: According to the shape of the connecting surface and the sealing structure, the flange can be divided into flat welded flange, butt welded flange, loose sleeve flange, etc.

Flange size: The size of the flange is usually expressed as the nominal diameter (DN) of the pipe, and the flange size may vary from standard to standard.

Flange pressure rating: The pressure rating of the flange connection is usually indicated by PN (European standard) or Class (American standard), and different grades correspond to different working pressure and temperature ranges.

Sealing surface form: flange sealing surface in a variety of forms, such as plane, convex surface, concave and convex surface, mortising surface, etc., should be based on the nature of the fluid and sealing requirements to choose the appropriate sealing surface form.

 

The use of internal and external threads to close the valve and the pipeline, mainly suitable for small diameter, low pressure pipeline system.

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Advantages:

Simple connection, easy operation, no special tools or equipment required.

Suitable for the connection of small diameter valves and low pressure pipelines, low cost.

Cons:

The sealing performance is relatively poor and it is easy to leak.

Only suitable for low pressure and low temperature conditions, for high pressure and high temperature environments, threaded connections may not meet the requirements.

 

Threaded connection is mainly used for small diameter valves and low pressure pipeline systems, and its standards mainly include the following aspects:

Thread type: Commonly used thread types are pipe thread, taper pipe thread, NPT thread, etc., should be selected according to the pipe material and connection requirements of the appropriate thread type.

Thread size: The size of the thread is usually expressed in nominal diameter (DN) or pipe diameter (inch), and the thread size may vary from standard to standard.

Sealing material: To ensure the tightness of the connection, sealing materials such as sealant or sealing tape are usually applied to the threads.

 

The valve is welded directly to the pipe through the welding process, which is suitable for scenarios requiring high sealing and permanent connection.

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Advantages:

High connection strength, good sealing, corrosion resistance, suitable for permanent and highly sealed occasions, such as petroleum, chemical and other industries of the pipeline system.

Cons:

Requires professional welding equipment and operators, installation and maintenance costs are high.

Once welded, the valve and pipe will form a whole, which is not easy to disassemble and repair.

 

Welded connections are suitable for scenarios that require high sealing and permanent connections, and their standards mainly include the following aspects:

Weld type: The common weld types are butt welds, fillet welds, etc., and the appropriate weld type should be selected according to the pipe material, wall thickness and connection requirements.

Welding process: The selection of welding process should be comprehensively considered according to the material, thickness and welding position of the base metal to ensure welding quality and connection strength.

Welding inspection: Necessary inspection and testing should be carried out after the completion of welding, such as appearance inspection, non-destructive testing, etc., to ensure the quality of welding and the tightness of the connection.

 

One end of the valve is a socket, the other end is a jack, by inserting and sealing to connect, often used in plastic piping systems.

There are clamping devices on both sides of the valve, and the valve is fixed on the pipeline through the clamping device, which is suitable for quick installation and disassembly.

Bushing connections are usually used in plastic piping systems to connect pipes to valves through special bushing tools and bushing pieces. This connection method has the characteristics of simple installation and convenient disassembly.

Adhesive connection is mainly used in some non-metal pipe systems, such as PVC, PE and other pipes. The pipe is bonded to the valve by using a special adhesive to form a permanent connection.

Commonly known as trench connection, this is a quick connection method that requires only two bolts and is suitable for low-pressure valves that are often removed. The connection pipe fittings include two categories of products: (1) The pipe fittings that play the role of connection sealing have rigid joints, flexible joints, mechanical tees and grooved flanges; The pipe fittings that play the role of connecting the transition are elbows, three-way, four-way, reducing pipes, blind plates, etc

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Valve connection forms and standards are important factors to ensure the safe and reliable operation of valves and piping systems. When selecting the appropriate connection form, factors such as pipe material, working pressure, temperature range, installation environment and maintenance requirements should be considered comprehensively. At the same time, the relevant standards and specifications should be followed during the installation process to ensure the correctness and tightness of the connection to ensure the normal operation of the fluid pipeline system.