Precautions for the installation of needle valves

1) The installation position, height, and inlet and outlet directions must meet the design requirements, and the direction of medium flow should be consistent with the direction of the arrow marked on the valve body, and the connection should be firm and tight.

2) The visual inspection must be carried out before the valve is installed, and the nameplate of the valve should comply with the provisions of the current national standard "General Valve Mark" GB 12220. For valves with working pressure greater than MPA and shut-off on the main pipe, strength and tightness performance tests should be carried out before installation, and they should be used only after they are qualified. During the strength test, the test pressure is times of the nominal pressure, the duration is not less than 5min, and the valve housing and packing should be qualified without leakage.

During the tightness test, the test pressure is multiple of the nominal pressure; The duration of the test meets the requirements of GB 50243.

Here are some of the well-known brands recognized in the valve industry, which are widely recognized and have a high reputation. While rankings may vary depending on time and market conditions, the following brands are generally considered to be among the top brands in the valve industry:

The following influential first-line brands of water system valves and industrial valves can be used as a reference, but for reference only: Suzhou Neway Valve, Shanghai Guanlong Valve, Shanghai Qizhong Valve, Sanhua, Su Yan, Shentong, Su Valve, Nanfang, Jiang.

First, the word Yao. The above manufacturers are only estimates and references, and the specific situation may vary or fluctuate at any time due to changes in a series of factors such as changes in the market, the size of the competition pattern, and the stability of product quality. As an indispensable key device in industrial production and civil facilities, the quality and reputation of the valve brand directly affect the satisfaction and trust of users.

These brands are known in the valve industry for their innovative technology, high-quality products and reliability. It is important to note that the market and industry are evolving rapidly, and different rankings may vary depending on time and region. For the most up-to-date ranking information, it is recommended to refer to industry reports, professional organizations or market research data for more detailed and accurate information.

Speaking of needle valves, I believe many people feel unfamiliar. However, many of you have seen a very pointed cone in a flame cutting saw or instrument measuring piping system. It is inserted like a needle into the valve seat of the piping system.

This very sharp cone is the needle valve. So, what is a needle valve?

What is a Needle Valve?

A needle valve is a valve that can be precisely adjusted by the piping system, and is named a needle valve because of its needle-like appearance. The biggest function of the needle valve is to cut off the fluid, and it has excellent sealing properties and can withstand very high pressures. In general, needle valves are used in conjunction with pressure gauges.

How should needle valves be selected?

There are many types of needle valves according to their production materials, use environments and other aspects, which makes people encounter many problems in the process of purchasing needle valves. Below, I will briefly introduce to my friends which type of needle valve should be chosen under different conditions.

When used in the piping system or device of cryogenic medium, a cryogenic needle valve with a bonnet should be used;

In the chemical industry, due to the large number of corrosive media in the pipeline system and device, it is most suitable to choose an all-stainless steel needle valve with stainless steel as the main material and PTFE as the seat sealing ring;

In the case of high-temperature media in metallurgy, electric power and petrochemical pipeline systems and devices, it is most suitable to choose the use of metal sealed needle valves;

In the oil refining industry, due to the catalytic or cracking device installed in the pipeline, it is most suitable to choose a needle valve with a lifting rod;

In the pipeline system that needs to be regulated, it is most appropriate to choose a worm gear drive, pneumatic or electric regulating needle valve with a V-shaped opening;

In addition, when the piping system needs to be buried underground, it is best to choose a needle valve with a full bore welded connection or a flange connection.

What should I pay attention to when installing a needle valve?

Needle valves are generally installed in the pipeline system to cut off the fluid in the pipeline. Therefore, when installing, it is necessary to ensure that the needle valve is installed correctly, and should be paid attention to

1. Before installing the needle valve, you need to check whether the appearance of the needle valve is intact. A needle valve with a certificate of conformity must be installed to ensure that the needle valve meets the national standard;

2. The installation position, height and inlet and outlet direction of the needle valve must meet the design requirements, and the direction of the arrow marked on the valve body should be consistent with the direction of the medium flow.

The above is some introduction to the needle valve, as well as some basic principles when choosing and using the needle valve, I hope it will be helpful to friends.

You can get it for free

1. Before installation, it is necessary to carefully verify whether the needle valve used meets the requirements of use, such as type, caliber, nominal pressure, applicable medium, etc.

2. Remove the impurities on the sealing surface of the valve cavity. Do not open or close the needle valve until the impurities are removed.

3. Select the appropriate packing according to the characteristics of the medium, and check whether the packing is compressed. However, it should not be pressed too tightly so as not to hinder the rotation of the stem.

4. Test the pressure according to the above method and make a record.

5. When lifting, the sling is not allowed to be tied to the handwheel, but should be tied to the valve body. It should be lifted gently, and it is strictly forbidden to hit and knock to prevent damage to the needle valve, especially to prevent damage to the sealing surface and valve stem.

6. When installing the non-standard flange to connect the needle valve, the non-standard flange should be parallel to the pipeline flange, and the flange should be properly guarded, and there should be no defects such as wrong mouth and mouth opening. Appropriate jumping gaskets (oil-resistant rubber asbestos boards, polytetra-ethylene gaskets) should be selected between the flanges, and the gaskets should be placed in the center and should not be deviated. Bolts should be tightened evenly and symmetrically, not too tightly or too loosely.

After the bolt is laid, check whether the clearance in all directions is consistent with a few feeler gauges.

7. The needle valve with threaded overpass should wrap the sealing material (PTFE raw tape, lead oil hemp fiber) on the thread, and then tighten it. Be careful not to get the sealing material into the valve cavity. For cast iron and non-metallic needle valves, the threads should not be overtightened to avoid bursting the needle valves.

8. When installing the welding needle valve, it should be aligned and spot welded first, then the valve disc should be opened, and finally the whole valve should be welded firmly. After the welding is completed, the weld should be checked for defects such as porosity, slag inclusion and cracks. After passing the inspection, the line and needle valve should also be purged and flushed.