Operating conditions for plug valves and ball valves

When used for cutting off flow, plug valves offer slightly better control capabilities compared to ball valves, but this advantage is limited. Although plug valves have much larger sealing surfaces than ball valves, which results in better sealing, it also leads to high torque and reduced flexibility in operation. Due to the weight of the plug itself, it is difficult to achieve large diameters in conventional plug valve designs. If large-sized valves are to be used, a reverse plug structure must be employed, with the larger end of the plug facing downward. As a result, gravity inevitably reduces the sealing efficiency, forcing the use of grease for sealing. The lubricating grease used means that such valves can only be applied in the storage and transportation of natural gas and oil, as they cannot be used in other industries due to the risk of the grease contaminating the medium. Although ball valves theoretically have a slightly poorer sealing performance, they can be manufactured in large diameters. Moreover, with improvements in manufacturing precision and sealing materials, their sealing performance is now sufficient to meet the requirements of practical applications, allowing for a wider range of uses. When used for adjustment, the two are not very different either; appropriate holes can be made in the rotating body for adjustment purposes. Therefore, plug valves are generally used in applications with high sealing requirements, but they usually have smaller diameters, whereas ball valves can be applied in more and a wider range of industrial scenarios. We generally use plug valves for level gauges, while ball valves are used in most other applications.

I generally agree with the view expressed above. Ball valves have large sealing surfaces, which ensures good sealing performance; they are very effective in applications where high sealing standards are required, such as those involving toxic gases. Moreover, thanks to their self-adjusting bolts, their service life is longer than that of ball valves. Generally, valves larger than 4 inches require a driving device, such as a worm gear box, pneumatic, or electric drive. However, torque testing is required for plug valves before they leave the factory, and the level of torque control in these valves serves as a criterion for assessing their quality. This is because the quality of assembly of the plug valve directly determines its overall quality. The reason why there are many manufacturers of ball valves in the market but few of plug valves is due to such inherent characteristics of plug valves. For large-diameter plug valves, an inverted design is not necessarily required; it depends on the pressure difference. When the pressure difference is low, such a design is not needed at all, while when the pressure difference is higher, a structure with a fixed bottom can be used. Plug valves are generally considered to have small diameters, as there aren’t many available in larger sizes on the market, and price factors also play a role in this. It has nothing to do with the product itself. Personal opinion!