How to choose a steam stop valve

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How to choose a steam globe valve: Globe valves can be used in various applications that require on/off control; they are used to change the flow direction of the process medium； Truncating the fluid is done for: equipment maintenance, removing the equipment, and shutting down the equipment. The linear motion characteristic of a globe valve is that the closing element moves in a straight line, but the flow direction of the fluid is perpendicular to the movement direction of the closing element. The main feature of a linear motion valve is that it closes tightly thanks to the closing element on the valve stem. The valve core of the stop valve is a ball valve, which is one of the main types of linear-motion valves and is widely used. The fluid must change direction at the valve core and seat of the stop valve, and then continue moving forward. This arrangement has one main advantage: the valve can be opened and closed more quickly, as the distance between the spherical valve core and the valve seat is short. This is a significant advantage when the valve needs to be opened and closed frequently. The downside is that the fluid has to change direction at the valve core, which increases flow resistance and can also cause turbulent vibrations. The spherical stop valve has a good seal, which means it can be used at higher temperatures and pressures, such as in steam systems; it is safer and results in less fluid loss. Due to the pressure of the upstream fluid acting on the valve core and transmitting this force to the valve stem, it becomes difficult to close the valve, which limits the diameter of ball globe valves to DN400 only. To prevent the process medium from leaking along the valve stem between the fluid and the external environment, a barrier is necessary; there are two types of valve stem sealing: gland packing sealing and bellows sealing. The gland packing is made of polymer materials, such as the typical PTFE, and is tightly filled between the valve stem and the gland to prevent leakage of the process medium. A telescopic metal bellows is used in the diaphragm-sealed globe valve; one end of the bellows is integrated with the valve stem, while the other end is pressed tightly against the valve cover, thereby preventing fluid leakage. The bellows expand and contract as the valve stem moves up and down, providing an extremely effective seal with zero leakage. The bellows is equipped with a anti-twist mechanism that prevents the bellows from twisting together with the valve stem; this mechanism is very important, as continuous twisting of the bellows would lead to failure and leakage. Although they are cheaper than diaphragm-sealed valves, gland packing-sealed valves do not provide as good a sealing performance as diaphragm seals. If a gland packing-sealed valve is not used for a certain period of time, the packing will harden, resulting in leaks when the valve is used again; this problem does not occur with diaphragm seals. Additionally, gland packing-sealed valves require regular replacement of the packing, whereas diaphragm-sealed valves generally do not need any maintenance even after 10,000 cycles of opening and closing. For the transportation, distribution, and use of steam, the best choice is a bellows-sealed globe valve. A large number of food processing companies are gradually replacing the plug valves equipped with packing on their steam pipes, especially on the steam distribution cylinders, with DBF bellows-sealed plug valves. DBF bellows-sealed globe valves have a service life of over 5 years; they operate very smoothly, and more importantly, they have never experienced any steam leakage issues, nor is it necessary to frequently maintain or replace the packing. It is not only easy to operate, with no issue of poor sealing, but also eliminates internal leakage ； The key is that the valve stem section is sealed using a high-titanium stainless steel bellows, thereby completely eliminating the possibility of external leakage. Practice has shown that one advantage of the WattSave bellows-sealed globe valve is that it requires no maintenance at all, **which reduces the need for maintenance in steam systems, saves costs, and minimizes unplanned downtime in food processing plants.