As an indispensable control element in the fluid pipeline system, valves have various connection forms to adapt to different application scenarios and fluid characteristics. The following are common valve connection forms and their brief descriptions:
1. Flange connection
The valve is connected to the pipeline by matching flanges and bolt fasteners, and is suitable for high temperature, high pressure and large diameter pipeline systems.
advantage:
The connection is firm and the sealing is good. It is suitable for valve connection under harsh conditions such as high pressure, high temperature and corrosive media.
Easy to disassemble and repair, making it easy to maintain and replace the valve.
shortcoming:
More bolts and nuts are required for installation, and the installation and maintenance costs are higher.
Flange connections are relatively heavy and take up more space.
Flange connection is a common valve connection method, and its standards mainly include the following aspects:
Flange type: According to the shape of the connecting surface and sealing structure, flanges can be divided into flat welding flanges, butt welding flanges, loose sleeve flanges, etc.

Flange size: The size of the flange is usually expressed in the nominal diameter (DN) of the pipe, and the flange size of different standards may vary.

Flange pressure grade: The pressure grade of flange connection is usually represented by PN (European standard) or Class (American standard). Different grades correspond to different working pressure and temperature ranges.

Sealing surface form: There are various sealing surface forms of flanges, such as flat surface, raised surface, concave and convex surface, tongue and groove surface, etc. The appropriate sealing surface form should be selected according to the fluid properties and sealing requirements.

2. Threaded connection
Threaded connections are mainly used for small-diameter valves and low-pressure pipeline systems. Its standards mainly include the following aspects:
advantage:
Simple to connect and easy to operate, no special tools or equipment required.

Suitable for connecting small diameter valves and low pressure pipelines with low cost.

shortcoming:
The sealing performance is relatively poor and leakage is prone to occur.

It is only suitable for low pressure and low temperature conditions. For high pressure and high temperature environments, the threaded connection may not meet the requirements.

Threaded connections are mainly used for small-diameter valves and low-pressure pipeline systems. Its standards mainly include the following aspects:
Thread type: Commonly used thread types include pipe thread, tapered pipe thread, NPT thread, etc. The appropriate thread type should be selected according to the pipe material and connection requirements.

Thread size: The size of the thread is usually expressed in nominal diameter (DN) or pipe diameter (inch). The thread size of different standards may be different.

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

3. Welding connection
The valve and the pipe are directly welded together through a welding process, which is suitable for scenarios that require high sealing and permanent connection.
advantage:
It has high connection strength, good sealing performance and corrosion resistance. It is suitable for occasions that require permanent and high sealing performance, such as pipeline systems in petroleum, chemical and other industries.

shortcoming:
It requires professional welding equipment and operators, and the installation and maintenance costs are high.

Once the welding is completed, 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. Its standards mainly include the following aspects:
Weld type: Common weld types include butt welds, fillet welds, etc. 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 based on factors such as the material, thickness and welding position of the base metal to ensure welding quality and connection strength.

Welding inspection: After welding is completed, necessary inspections and tests should be carried out, such as visual inspection, non-destructive testing, etc., to ensure the welding quality and the tightness of the connection.

4. Socket connection
One end of the valve is a socket and the other end is a spigot, which is connected by insertion and sealing. It is often used in plastic piping systems.
5. Clamp connection: There are clamping devices on both sides of the valve. The valve is fixed on the pipeline through the clamping device, which is suitable for rapid installation and disassembly.
6. Cutting sleeve connection: Cutting sleeve connection is usually used in plastic pipeline systems. The connection between pipes and valves is achieved through special cutting sleeve tools and cutting sleeve fittings. This connection method is easy to install and disassemble.
7. Adhesive connection
Adhesive connections are mainly used in some non-metallic pipe systems, such as PVC, PE and other pipes. A permanent connection is made by bonding the pipe and valve together using a specialized adhesive.
8. Clamp connection
Often called a grooved connection, this is a quick connection method that requires only two bolts and is suitable for low-pressure valves that are frequently disassembled. Its connecting pipe fittings include two major categories of products: ① pipe fittings that serve as connection seals include rigid joints, flexible joints, mechanical tees and grooved flanges; ② pipe fittings that serve as connection transitions include elbows, tees, and crosses , reducer, blind plate, etc.
The valve connection form and standard are important factors to ensure the safe and reliable operation of the valve and pipeline system. When selecting the appropriate connection form, factors such as pipe material, working pressure, temperature range, installation environment, and maintenance requirements should be comprehensively considered. At the same time, relevant standards and specifications should be followed during the installation process to ensure the correctness and sealing of connections to ensure the normal operation of the fluid pipeline system.