Ascending Efficiency: Rising Stem Valves in Critical Process Control
Nov 21,2023Read More
Valves pressure-bearing means the pressure that the valves can bear, that is, valves pressure level is larger than the pipeline’s designed pressure level. Valves pressure-bearing direction means that on the close state once applied to the pipeline, valve body's arrow direction is the recommended pressure-bearing direction. If installed in wrong way, maybe have the leakage caused by valves not closed tightly. Generally decided by the using technological process or using situation, the same direction means the pressure-bearing direction(high medium pressure side on both sides of valves gate) keep same as the flow direction, opposite direction means pressure-bearing direction(high medium pressure side on both sides of valves’ gate) keep opposite as the flow direction.
Many kinds of valves have the direction, such as globe valves, throttle valves, pressure reducing regulator valves, check valves and etc. If installed in opposite direction, will affect the using effect and using life(such as throttle valves), or don’t work at all(such as pressure reducing valves), even cause dangerous(such as check valves). General valves will have direction marks showed on the valve body, if haven't, should identified correctly according to the valves working principle.
The arrow showed on the valves body is the recommended pressure-bearing direction, not means the pipe medium’s flow direction. The valve with bi-directional sealing function can not mark the indicated arrow, but also can be marked, because the valve arrow refers to the recommended pressure direction, always have one is better in the left and right directions or up and down directions. Usually installed as the mark of medium flow direction by the engineering company, will cause the leakage or even cause the pipeline accident;
The valve chamber for a globe valve is not symmetrical, the fluid should be passed through the valve port from bottom to top, so will cause smaller flow resistance(decided by the situation), and opened easily(because the medium’s pressure is upward), after closing, the medium doesn’t press the packing for easy maintenance. That is the reason why globe valves cannot be installed in opposite direction. The other kinds of valves also have their own characters.
The valve installed location should be easy for operation; even if the installation is temporarily difficult, it is necessary to consider the long-term work of the operator. It is better to keep the valve handwheel with same location with the chest(usually have 1 or 2 meters away from the operation floor), so that the valve is relatively easy to open and close. The ground valve's handwheel should be upward, do not tilt, to avoid awkward operation.
The valve in the wall machinery equipment should also keep the room for the operator to stand. Should avoid operating face to the sky, especially for the medium of acid, alkali and toxic media, otherwise it is very dangerous.
The gate valves shouldn’t be installed reversely(means handwheel is downward), otherwise the medium will be retained in the bonnet space for a long time, which will cause the stem to be corroded and it is taboo for some industrial requirements. Meanwhile, it is extremely inconvenient for changing the packing. The rising stem gate valves should not be installed underground, otherwise will corrode the exposed stem because of the wet. Lift control valves once installed should ensure the disc vertical so that can lift flexibly. Swing check valves once installed should ensure the horizontal pin shaft so that can swing flexibly. Pressure-reducing valves should be installed on a horizontal pipeline with up-right, and any direction can not be tilted.
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