Selection method of globe valves for different operating conditions

Stop valves are durable due to the low friction between the sealing surfaces during the opening and closing process, with a small opening height, easy manufacturing, and convenient maintenance. They are not only suitable for medium and low pressure, but also for high pressure. The closing principle of a globe valve is to rely on the pressure of the valve stem to tightly adhere the sealing surface of the valve disc to the sealing surface of the valve seat, preventing the flow of the medium.

Globe valves have a wide range of applications and types, including bellows globe valves, flange globe valves, internally threaded globe valves, externally threaded globe valves, welded globe valves, fluorine lined globe valves, stainless steel globe valves, ammonia globe valves, gas globe valves, DC globe valves, needle globe valves, Y-shaped globe valves, angle globe valves, insulation globe valves, low-temperature globe valves, cast iron globe valves, cast steel globe valves, forged steel globe valves, high-pressure globe valves, pneumatic globe valves, and electric globe valves; How to select is very important, and it needs to be selected based on the medium, temperature, pressure, operating conditions, and control requirements. The specific selection rules are as follows:

1. Electric globe valves and pneumatic globe valves should be selected for pipelines or devices with high temperature and high pressure media. High temperature and high-pressure pipelines in thermal power plants, steam, thermal oil, and petrochemical systems;

2. Direct flow globe valves can be used on pipelines with less stringent requirements for flow resistance;

3. Small pneumatic globe valves can be selected from needle valves, instrument valves, sampling valves, pressure gauge valves, etc;

4. There is flow regulation or pressure regulation, but the requirement for regulation accuracy is not high, and the pipeline diameter is relatively small. For example, on pipelines with a nominal diameter ≤ 50mm, pneumatic globe valves and electric regulating valves are selected;

　　

Ammonia shut-off valve - Yonglong valve

5. For easily solidified crystallization media, insulation shut-off valves and hard sealed shut-off valves should be selected;

6. Forged globe valves and high-pressure globe valves should be selected for high-pressure environments;

7. Small and large fertilizers in synthetic industrial production should use high-pressure angle globe valves or high-pressure angle throttling valves with nominal pressures of PN160/16MPa or PN320/32MPa;

8. In the desilication workshop and coking prone pipelines of alumina Bayer process production, it is easy to choose DC globe valves or DC throttling valves with separate valve bodies, removable valve seats, and hard alloy sealing pairs;

9. For water supply and heating projects in urban construction, pneumatic globe valves, balance valves, or plunger valves can be used for pipelines with a nominal diameter of less than 150mm.

　　

Bellows globe valve - Shanghai Yonglong

10. High temperature steam, thermal oil, hydrogen, and oxygen select bellows globe valves.

11. For low-temperature liquid oxygen, liquid nitrogen, liquefied petroleum gas, and LNG media, long neck low-temperature shut-off valves are selected.

12. Stainless steel globe valves or fluorine lined globe valves should be selected for acid-base globe valves.

13. Select ammonia shut-off valves, gas shut-off valves, reverse sealing shut-off valves, and self sealing shut-off valves for ammonia, ammonia, gas, coal gas, liquefied gas, and toxic and harmful media.

The opening and closing component of a stop valve (Globe Valve) is a plug shaped valve disc, with a flat or conical sealing surface. The valve disc moves linearly along the centerline of the valve seat. The movement form of the valve stem, commonly known as the concealed rod, can also be used to control the flow of various types of fluids such as air, water, steam, thermal oil, mud, oil, liquid ammonia, gas, liquid metal, and radioactive media through the lifting and rotating rod type.