Many valve products have directionality, such as globe valves, throttle valves, pressure reducing valves, check valves, etc. The use effect and service life will be affected if they are installed upside down or reversed (such as throttle valves), or even have no effect (such as pressure reducing valves), which may even cause danger (such as check valves). Generally, there is a directional mark on the valve body; if not, it should be identified correctly according to the working principle of the valve. The valve chamber of the globe valve is asymmetric left and right, and the fluid should pass through the valve port from bottom to top, so that the fluid resistance is small (determined by the shape), and the opening is labor-saving (because the medium pressure is upward), and the medium does not press the filler after closing, which is easy for maintenance. Other valves have their own characteristics as well.
The installation position of industrial valves must be convenient for operation: even if the installation is temporarily difficult, it should consider the long-term work of the operators. The valve handwheel should ideally be aligned with the chest (generally 1.2 meters away from the operating floor), so that opening and closing the valve is easier. The handwheel of a floor valve should be facing upwards and not tilted to avoid inconvenience during operation. Valves near the wall or equipment should also leave space for operators to stand. Avoid operating the valve upwards, especially for acidic, alkaline, or toxic media, as it is unsafe. Gate valves should not be installed upside down (i.e., with the handwheel facing downwards), as the medium will remain in the valve cover space for a long time and corrode the valve stem, which is also forbidden in some process requirements. It is also extremely inconvenient to replace the packing. Stem gate valves should not be installed underground, otherwise the valve stem exposed due to dampness may cause corrosion. For lifting check valves, the valve flap should be installed vertically to facilitate flexible lifting. For rotary check valves, the pin axis should be installed horizontally to facilitate flexible rotation. Pressure reducing valves should be installed upright on horizontal pipelines without tilting in any direction.
The installation construction must be careful to avoid hitting valve products made of brittle materials. Before installation, the valve should be inspected to verify the specifications and models, and to identify any damages, especially to the valve stem. It should also be turned a few times to see if it is askew, as the valve stem is easily hit out of shape during transportation. The impurities inside the valve should also be cleared. When lifting the valve, the rope should not be tied to the handwheel or valve stem to avoid damaging these parts. Instead, it should be tied to the flange.
For the pipeline connected to the valve products, it must be cleaned thoroughly. Compressed air can be used to blow away rust, sand, welding slag, and other impurities. These impurities can not only easily scratch the sealing surface of the valve but also block small valves, rendering them ineffective, especially for larger impurities (such as welding slag). When installing a screw valve, the sealing filler (hemp thread plus aluminum oil or PTFE raw material tape) should be wrapped around the pipe thread and not into the valve to avoid accumulation inside the valve and affecting the medium flow.
When installing a flange valve, attention should be paid to tightening the bolts symmetrically and uniformly. The valve flange and pipe flange must be parallel, with reasonable clearance, to avoid excessive pressure on the valve, and even cracking. This is especially important for valves made of brittle materials or with low strength. For valves that need to be welded to pipes, they should be spot-welded first, the closing piece should be fully opened and then welded shut.
Some industrial valves also require external protection, which is insulation and cooling. Sometimes there is a need to heat steam pipelines in the insulation layer. Whether a valve should be insulated or cooled depends on production requirements. If the temperature of the medium inside the valve drops too much, affecting production efficiency or freezing the valve, insulation is needed, even with the addition of heat. If the valve is exposed, it is not conducive to production, or causes frost and other adverse phenomena, cooling is needed. Insulation materials include asbestos, slag wool, glass wool, perlite, diatomaceous earth, and vermiculite, while cooling materials include cork, perlite, foam, and plastics, among others.
Some valve products require bypass and instruments in addition to necessary protective facilities. Installing a bypass facilitates the maintenance of steam trap valves. Other valves also have bypasses installed, depending on the condition of the valve, the importance, and the production requirements.
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