What is a ball valve?

Ball valve is defined in the standard GB/T21465-2008 "Valve Terminology" as a valve whose opening and closing part (ball) is driven by the valve stem and rotates around the axis of the ball valve. It can also be used for the regulation and control of fluids, among which the hard-sealed V-shaped ball valve has a strong shear force between its V-shaped ball core and the metal valve seat of surfacing welding carbide, and is especially suitable for fibers and tiny solid particles. etc. medium. The multi-way ball valve can not only flexibly control the confluence, diversion, and flow direction switching of the medium on the pipeline, but also close any channel and connect the other two channels. This type of valve should generally be installed horizontally in the pipeline. According to the driving mode, the ball valve is divided into: pneumatic ball valve, electric ball valve, manual ball valve.

The ball valve came out in the 1950s. With the rapid development of science and technology, the continuous improvement of production technology and product structure, it has rapidly developed into a major valve category in just 40 years. In western industrially developed countries, the use of ball valves is increasing year by year.

The ball valve is mainly used to cut off, distribute and change the flow direction of the medium in the pipeline. It only needs to be rotated 90 degrees and a small rotational torque can be closed tightly. Ball valves are most suitable for on-off and shut-off valves, V-type ball valves. In addition to paying attention to the pipeline parameters, the electric valve should also pay special attention to the environmental conditions of its use. Since the electric device in the electric valve is an electromechanical device, its use status is greatly affected by its use environment. In general, special attention should be paid to the use of electric ball valves and butterfly valves in the following environments.

What are the common ball valve materials?

1. Gray cast iron: Gray cast iron is suitable for media such as water, steam, air, gas and oil with a nominal pressure PN≤1.0MPa and a temperature of -10°C to 200°C. Common grades of gray cast iron are HT200, HT250, HT300, HT350.

2. Malleable cast iron: suitable for water, steam, air and oil media with nominal pressure PN≤2.5MPa and temperature of -30~300℃. The commonly used grades are KTH300-06, KTH330-08, KTH350-10.

3. Ductile cast iron: suitable for water, steam, air, oil and other media with PN≤4.0MPa and temperature of -30～350℃. Common grades are QT400-15, QT450-10, QT500-7.

4. Acid-resistant high-silicon ductile iron: suitable for corrosive media with nominal pressure PN≤0.25MPa and temperature lower than 120°C.

5. Carbon steel: suitable for media such as water, steam, air, hydrogen, ammonia, nitrogen and petroleum products with a nominal pressure PN≤32.0MPa and a temperature of -30~425°C. Commonly used grades are WC1, WCB, ZG25, high-quality steel 20, 25, 30 and low-alloy structural steel 16Mn.

6. Copper alloy: suitable for water, seawater, oxygen, air, oil and other media with PN≤2.5MPa, as well as steam media with a temperature of -40 to 250 ° C. The commonly used grades are ZGnSn10Zn2 (tin bronze), H62, Hpb59-1 (brass), QAZ19-2, QA19-4 (aluminum bronze).

7. High-temperature copper: suitable for steam and petroleum products with nominal pressure PN≤17.0MPA and temperature≤570℃. Commonly used grades are ZGCr5Mo, 1Cr5M0.ZG20CrMoV, ZG15Gr1Mo1V, 12CrMoV, WC6, WC9 and other grades. The specific selection must be in accordance with the provisions of the ball valve pressure and temperature specifications.

8. Low-temperature steel: suitable for nominal pressure PN≤6.4Mpa, temperature ≥-196°C ethylene, propylene, liquid natural gas, liquid nitrogen and other media, commonly used grades) are ZG1Cr18Ni9, 0Cr18Ni9, 1Cr18Ni9Ti, ZG0Cr18Ni9.

9. Stainless acid-resistant steel: suitable for mediums such as nitric acid and acetic acid with nominal pressure PN≤6.4Mpa and temperature≤200℃. Commonly used grades are ZG0Cr18Ni9Ti, ZG0Cr18Ni10 resistant to nitric acid, ZG0Cr18Ni12Mo2Ti, ZG1Cr18Ni12Mo2Ti resistant to acid and urea.