1. Installation Position and Location 

Many valves are specific. For instance, stop valves, relief valves, pressure regulating valves, products, etc. If they are installed in the wrong direction, it will affect the application effect and service life (such as relief valves), or become essentially inoperative (such as pressure regulating valves), or even cause risks (such as products). Generally, valves on the oil circuit board have direction indicators. If not, they should be properly identified based on the valve principle. 

The upper and lower parts of the valve cavity of a stop valve are not the same. From a fluid mechanics perspective, it should be installed with the flow direction from bottom to top. This way, the fluid friction resistance is small (determined by its shape), it is easier to open (due to the upward pressure of the medium), and after closing, the medium does not press the packing, which is conducive to maintenance. This is the main reason why a stop valve cannot be installed in reverse. Other types of valves also have their own distinct features. 

The installation position of the valve must be convenient for operation. Even if the installation is temporarily difficult, it will be considered for the long-term work of the operator. It is best for the valve handle to be at chest level (usually 1.2 meters from the operation floor), so that opening and closing the valve is more effortless. The handle of floor-mounted valves should be upward and not tilted to avoid awkward operation. For valves attached to the wall or equipment, there should also be space for the operator to stand. Avoid operating while looking up, especially for strong acids, strong alkalis, and hazardous substances, as it is very unsafe. 

The water control gate does not need to be installed upside down (i.e., with the handle pointing down), otherwise it will cause substances to remain in the valve cover space for a long time, which is very likely to corrode the valve seat and is also undesirable for some process requirements. Additionally, replacing the packing is extremely convenient. For the rising stem gate valve, it should not be installed underground, otherwise the exposed valve seat will be corroded due to moisture and cold. When installing this product, ensure that the piston valve is vertical to facilitate smooth lifting. For this product, when installing, ensure that the pin is horizontal to facilitate smooth rotation. The pressure regulating valve should be installed upright on a horizontal pipeline and should not be tilted in any direction. 

II. Construction Work 

When installing the project, be extremely careful and avoid bumping into the valves made of ductile materials. 

What should be done before installation? 

All valve models, specifications and types should be carefully checked to see if they meet the design requirements. (According to the valve model and the manufacturer's instructions, check if they can be used under the specified conditions. If necessary, conduct pressure or standard pressure tests.) 

In addition, it is necessary to check whether the filler is intact, whether the adjusting capacity of the foot bolts of the screw cap is sufficient, and then check whether the valve seat and the valve disc are flexible, and whether there is any jamming or tilting. (The valve disc's raised surface must be tightly closed. For valves connected by bolts, the quality of the external threads should be checked. Valves that do not meet the requirements cannot be installed and should be stacked again or marked properly.) 

3. Remove the dirt inside the valve. 

Installation process: 

When hoisting the valve, the rope should not be tied to the handle or the valve seat to prevent damage to these components. Instead, it should be tied to the flange. 

2. For the pipelines connected to the valves, they must be cleaned thoroughly. Compressed air can be used to blow away air-oxidized iron filings, drilling mud, welding spatters and other dirt. Such dirt not only can easily scratch the valve face, but also large particles of dirt (such as welding spatters) can clog small valves, rendering them ineffective. 

When installing the spiral lamp valve, the sealing filler (hemp thread with aluminum oil or raw polytetrafluoroethylene tape) should be wrapped around the outer thread of the water pipe. It is not necessary to put it inside the valve to prevent accumulation during valve operation, which may hinder the flow of substances. 

When installing flange valves, pay attention to the symmetry and evenly tighten the anchor bolts. The flange of the valve must be parallel to the flange of the water pipe, with an effective gap to prevent the valve from being subjected to excessive pressure and even cracking. Special attention should be paid to valves made of ductile materials and those with too low strength. For valves that need to be welded to the water pipe, weld them first, then fully open the shut-off part, and then weld them shut. 

III. Safeguard Measures 

Some valves also need external maintenance, which means thermal insulation and cold insulation. Sometimes, heating steam pipes are added inside the insulation layer. Which valves should be thermally insulated or cold insulated depends on the manufacturing regulations. 

Strictly speaking, if the temperature of the material inside the valve drops too much, it will affect the production rate or cause the valve to crack due to freezing, then insulation and heat preservation measures must be taken, or even heating. If the valve is exposed outside and there are safety hazards such as poor manufacturing or frosting, then cold insulation measures must be taken. Insulation and heat preservation materials include asbestos, fly ash cotton, glass fiber cotton, perlite, attapulgite, vermiculite, etc. Cold insulation materials include cork board, perlite, foam plastic, plastic, etc. 

IV. Dual Circuit Power Supply and Instrument Panel 

Some valves, in addition to the necessary maintenance equipment, also require dual power supply circuits and instrument panels. Installing dual power supply circuits is beneficial for the maintenance of steam traps. Other valves are also equipped with dual power supply circuits. Whether to install dual power supply circuits depends on the valve's condition, necessity, and manufacturing regulations. 

V. Replacement of Filling Materials 

Some of the packing materials in the inventory valves are no longer in good condition, and some do not match the applied substances. Therefore, it is necessary to replace the packing materials. The valve manufacturing factory cannot take into account the thousands of different substances used by application enterprises. The stuffing box is always filled with common packing materials, but when in use, the packing material must be consistent with the substance. 

When replacing the packing material, it should be pressed in circle by circle. The angle at each joint should be 45 degrees, and the joints between circles should be separated by 180 degrees. The height-to-width ratio of the packing material should take into account the space for the screw cap to be re-tightened. Currently, the lower edge of the screw cap should press the packing material chamber to a certain depth, which is usually 10-20% of the total depth of the packing material chamber. For valves of specified height, the angle at the joint should be 30 degrees, and the joints between circles should be separated by 120 degrees. 

In addition to the aforementioned packing materials, depending on the specific circumstances, other formed packing materials such as three-layered stacked PTFE rings (resistant to strong corrosive substances up to 200°C), polyester bowl-shaped rings (resistant to ammonia and alkali up to 120°C), and O-rings made of vulcanized rubber (natural rubber resistant to alkaline substances up to 60°C, nitrile rubber resistant to oil up to 80°C, and fluorine rubber resistant to various corrosive substances up to 150°C) can also be selected. Wrapping a layer of PTFE raw tape around the usual asbestos packing can enhance the sealing effect and alleviate the galvanic corrosion of the valve seat. When tightening the packing, rotate the valve seat at the same time to ensure evenness around and avoid over-tightening. When tightening the cover, apply even force and do not tilt.