(1) Orientation and location
Many valves are directional, such as globe valve, throttle valve, pressure reducing valve, check valve, etc. If they are installed upside down, it will affect the use effect and life (such as throttle valve), or not work at all (such as pressure reducing valve), or even a hazard (such as a check valve). Generally, the valve has a direction mark on the valve body; if not, it should be correctly identified according to the working principle of the valve. The valve cavity of the globe valve is asymmetrical, 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 pressure of the medium is upward), and the medium does not press the packing after closing, which is convenient for maintenance. , this is the reason why the globe valve cannot be reversed. Other valves also have their own characteristics.
The installation position of the valve must be easy to operate: even if the installation is temporarily difficult, the long-term work of the operator must be considered. It is best to align the valve handwheel with the chest (usually 1.2 meters away from the operating floor), so that it is easier to open and close the valve. The handwheel of the landing valve should be upward, not inclined, so as to avoid awkward operation. The valve of the machine against the wall should also leave room for the operator to stand. It is necessary to avoid operation in the sky, especially acid and alkali, toxic media, etc., otherwise it is very unsafe. The gate should not be installed upside down (that is, the handwheel is downward), otherwise the medium will remain in the valve cover space for a long time, which will easily corrode the valve stem, and is prohibited by certain process requirements. It is extremely inconvenient to replace the packing at the same time. The rising stem gate valve should not be installed underground, otherwise the exposed valve stem will be corroded due to moisture. When installing the lift check valve, ensure that its disc is vertical so that it can be lifted flexibly. When installing the swing check valve, ensure that its pin shaft is level so that it can swing flexibly. The pressure reducing valve should be installed upright on the horizontal pipeline, and should not be inclined in all directions.
(2) Construction work
Installation and construction must be careful, avoid hitting the valve made of brittle material.
Before installation, the valve should be inspected to check the specifications and models to identify whether there is damage, especially for the valve stem. Turn it a few times to see if it is skewed, because during transportation, the valve stem is most likely to be skewed. Also remove debris from the valve.
When the valve is lifted, the rope should not be tied to the handwheel or valve stem to avoid damage to these parts, and should be tied to the flange.
For the pipeline connected to the valve, be sure to clean it. Compressed air can be used to blow off iron oxide filings, mud sand, welding slag and other debris. These debris not only easily scratch the sealing surface of the valve, but also block the small valve and make it invalid. When installing a screw valve, the sealing packing (line hemp plus aluminum oil or PTFE raw material tape) should be wrapped on the pipe thread, and do not get into the valve, so as to avoid accumulation in the valve and affect the flow of the medium.
When installing flanged valves, pay attention to tightening the bolts symmetrically and evenly. The valve flange and the pipe flange must be parallel with a reasonable gap to avoid excessive pressure or even cracking of the valve. Special attention should be paid to brittle materials and valves with low strength. Valves that must be welded to the pipe should be spot welded first, then the closing parts should be fully opened, and then welded to death.
(3) Protection measures
Some valves must also have external protection, which is heat preservation and cold preservation. Sometimes a hot steam line is added to the insulation layer. What kind of valve should be kept warm or cold depends on the production requirements.
In principle, if the medium in the valve lowers the temperature too much, which will affect the production efficiency or freeze the valve, it needs to be kept warm, or even heated; when the valve is exposed, it is unfavorable to production or causes adverse phenomena such as frost, it needs to be kept cold. Insulation materials include asbestos, slag wool, glass wool, perlite, diatomite, vermiculite, etc.; cold insulation materials include cork, perlite, foam, plastic, etc.
(4) Bypass and instrumentation
For some valves, in addition to the necessary protection facilities, there are also bypasses and instruments. Bypass installed. Easy to repair the trap. Other valves also have bypasses installed. Whether to install a bypass depends on the valve condition, importance and production requirements.
5) Pad replacement
In stock valves, some rubber pads are not working well (exceeded the shelf life), and some are not in line with the medium used, which requires replacing the rubber pads.
The valve manufacturer cannot consider the use of thousands of different media. The configuration of the rubber pad will be mainly general, but when using it, the rubber pad must be adapted to the medium.
The selection of rubber pads can be based on the actual situation, using rubber O-rings (natural rubber is resistant to weak alkali below 60 degrees Celsius, nitrile rubber is resistant to oil crystals below 80 degrees Celsius, and fluorine rubber is resistant to various corrosive media below 150 degrees Celsius) three-piece stack Forming fillers such as PTFE ring (resistant to strong corrosive medium below 200 degrees Celsius) nylon bowl ring (resistant to ammonia and alkali below 120 degrees Celsius). Outside the ordinary asbestos packing, wrap a layer of PTFE raw material tape, which can improve the sealing effect and reduce the electrochemical corrosion of the valve stem.
When pressing the rubber pad, turn the valve stem at the same time to keep the circumference even and prevent it from being too dead. Tighten the gland with even force and not tilt.
Ningbo Baodi Plastic Valve Co., Ltd. is professional China ProductS Manufacturers and ProductS suppliers.Founded in 2006, the enterprise has established ISO9001 quality system to support the quality guideline: supported by Technology, Meticulously Researching, Professionally Manufacturing and Permanently Creating New Records. The first class production equipments and advanced manufacturing skills are introduced at the same time, involving KRAUSS-MAFFEL CPVC pipe production line and Haitian CPVC Plastic Molding Machine of 2800 tons. In order to ensure the quality of wholesale ProductS, the raw materials like CPVC and PVDF are wholly imported from Noveon (USA) and Atofina (France).