Instructions on the pressure-bearing direction and installation direction of the valve

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The last edit to this post was made by kn on 2020-6-12 at 10:20. The pressure rating of a valve refers, as the name suggests, to the pressure that the valve can withstand; in other words, the pressure rating of the valve must be at least equal to the design pressure rating of the pipeline. The pressure-bearing direction refers to the direction in which pressure is recommended to be applied, as indicated by the arrow on the valve body, when the valve is in the closed state under pipeline operation conditions. If installed incorrectly, leakage may occur due to the valve not closing properly. It is generally determined based on the operating process or usage conditions. The same direction refers to the situation where the pressure-bearing direction (the side with higher pressure of the medium on either side of the valve gate) is in line with the flow direction, while the opposite direction means that the pressure-bearing direction is opposite to the flow direction of the medium. Many valves are directional, such as globe valves, throttle valves, pressure relief valves, check valves, etc. If installed in the wrong orientation, it can affect their performance and lifespan (as in the case of throttle valves), or they may not function at all (as in the case of pressure relief valves), or it could even pose a danger (as in the case of check valves). For ordinary valves, there are direction indicators on the valve body ； In the event that it is not present, it should be correctly identified based on the working principle of the valve. The arrow marked on the valve body indicates the recommended pressure direction for the valve, rather than the flow direction of the fluid in the pipeline. Valves with a two-way sealing function may or may not have indicator arrows; either way is acceptable, as these arrows indicate the recommended direction for bearing pressure – there is always one direction, either left/right or up/down, that is preferable. It is often incorrectly installed by engineering installation companies as a medium flow direction marker, resulting in leaks and even pipeline accidents ； The valve chamber of the stop valve is asymmetrical on the left and right; the fluid must flow through the valve opening from bottom to top, which results in low fluid resistance (due to the shape of the valve). It is easy to open the valve as the medium pressure acts upward, and once closed, the medium does not exert pressure on the packing, facilitating maintenance. This is why stop valves cannot be installed in reverse. Other valves also have their own characteristics. The valve must be installed in a location that facilitates operation ； Even if installation is temporarily difficult, it is necessary to consider the operators’ long-term work. It is best for the valve handwheel to be at chest level (generally 1 above the operating floor). 2 meters), which makes it easier to open and close the valve. The handwheel of the floor valve should face upward and not be tilted, to avoid awkward operation. For wall-mounted units, space must also be left near the device’s valves for the operator to stand. It is necessary to avoid working with the head raised, especially when dealing with acids, bases, toxic substances, etc., as it is very unsafe. The gate valve should not be installed in an inverted position (with the handwheel facing downward), as this will cause the medium to remain in the space above the valve cover for an extended period, leading to corrosion of the valve stem; it is also prohibited by certain process requirements. It is also very inconvenient to replace the packing at the same time. Straight-through gate valves should not be installed underground, as moisture can cause corrosion of the exposed valve stem. For lift-type check valves, it is necessary to ensure that their valve discs are vertical during installation, so as to allow for smooth lifting and lowering. For swing check valves, it is necessary to ensure that their pin shafts are horizontal during installation, so as to allow for smooth swinging. The pressure relief valve must be installed vertically on a horizontal pipe, without any tilt in any direction.