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The quality of valve installation has a direct impact on its performance, so it must be given careful attention. 1. Installation direction and position of valves: Many valves are directional, such as globe valves, throttle valves, pressure relief valves, check valves, etc. If installed in the wrong direction, it will 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 available, it should be correctly identified based on the working principle of the valve. The valve chamber of a globe 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 easier to open the valve as the medium pressure acts upward, and once closed, the medium does not exert pressure on the packing, making maintenance easier. This is why a globe valve cannot be installed in reverse. Other valves also have their own characteristics. The valve installation location must be convenient for operation: even if installation is temporarily difficult, it is necessary to consider the operator’s long-term work needs. The valve handwheel should be at chest level (usually 1.2 meters above the operating floor), 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 substances that require looking up, especially acids, bases, toxic materials, etc., as it is very unsafe to do so. The gate must 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. 2. Valve installation work: Care must be taken during installation; avoid impacting valves made of brittle materials. Before installation, the valve should be inspected to verify its specifications and model, and to check for any damage, especially to the valve stem. It needs to be turned a few more times to check if it is skewed, as the valve stem can easily get misaligned during transportation. The debris inside the valve also needs to be removed. When lifting the valve, do not tie the rope to the handwheel or valve stem, as this may damage those components; instead, it should be tied to the flange. The pipelines connected to the valve must be thoroughly cleaned. Compressed air can be used to blow away iron oxide filings, sediment, slag, and other debris. These debris not only easily scratch the sealing surfaces of the valves, but large particles of debris (such as welding slag) can also block small valves, rendering them ineffective. When installing threaded valves, the sealing filler (flax mixed with aluminum grease or PTFE tape) should be wrapped around the pipe threads, avoiding contact with the inside of the valve, so as to prevent accumulation there and disrupt the flow of the medium. When installing flanged valves, be careful to tighten the bolts symmetrically and evenly. The valve flange and the pipe flange must be parallel with an appropriate gap, to prevent excessive pressure from being generated on the valve, which could even lead to cracking. Special attention should be paid to brittle materials and valves with low strength. For valves that need to be welded to pipes, spot welding should be performed first, followed by fully opening the closing element, and then carrying out the final welding. 3. Valve protection measures: Some valves also require external protection, namely insulation and cooling. Heating steam pipelines are sometimes also added inside the insulation layer. It depends on the production requirements to determine which types of valves should be insulated or insulated from heat. In principle, whenever the temperature of the medium inside the valve drops too much, it can affect production efficiency or damage the valve; in such cases, insulation is necessary, or even heating ； When valves are exposed, which is detrimental to production or can cause problems such as frosting, insulation is required. Insulation materials include asbestos, slag wool, glass wool, perlite, diatomite, vermiculite, etc ； Insulation materials include cork, perlite, foam, plastic, etc. 4. Bypasses and instruments: Some valves require bypasses and instruments in addition to the necessary protective devices. A bypass has been installed. Facilitates the maintenance of the steam trap. Other valves also have bypass installations. Whether to install a bypass depends on the condition of the valve, its importance, and the requirements of production. 5. Packing replacement: Among the valves in stock, some have packing that is no longer functional, and some use packing that is not suitable for the medium being handled; therefore, it is necessary to replace the packing. Valve manufacturers cannot take into account the wide variety of different media used by end-users; ordinary packing is always installed in the stuffing box, but it is necessary to adapt the packing to the specific medium being used. When replacing the packing, press it in circle by circle. The seam between each loop should be at 45 degrees, with a separation of 180 degrees between loops. The packing height must take into account the amount of further compression that the gland can provide; at the same time, it is necessary to allow the lower part of the gland to compress the packing chamber to an appropriate depth, which is generally 10-20% of the total depth of the packing chamber. For high-demand valves, the joint angle is 30 degrees. The seams between the circles are offset by 120 degrees. In addition to the aforementioned packing materials, shaped packing materials such as rubber O-rings (natural rubber is resistant to weak alkalis at temperatures below 60 degrees Celsius, nitrile rubber is resistant to oil droplets at temperatures below 80 degrees Celsius, and fluororubber is resistant to various corrosive agents at temperatures below 150 degrees Celsius), triple-layered polytetrafluoroethylene rings (resistant to highly corrosive agents at temperatures below 200 degrees Celsius), and nylon cup-shaped rings (resistant to ammonia and alkalis at temperatures below 120 degrees Celsius) can also be used depending on the specific circumstances. Wrapping a layer of PTFE tape around the ordinary asbestos packing can improve the sealing effect and reduce the electrochemical corrosion of the valve stem. When compressing the seasoning, turn the valve stem at the same time to ensure even distribution and prevent it from becoming too tight; apply even force when tightening the gland, without tilting it. Shanghai Automation Instruments Co., Ltd.: http://www.shanghai-saic.com/