Important ! Cautions to Install Brass Valves
Time:2019-03-29 From: NAFCO | Brass Valves Manufacturers China
The quality of the brass valve installation directly affects the use, so careful attention must be paid.
1. Direction and location
Many brass valves are directional, such as globe valves, throttle valves, pressure reducing valves, check valves, etc. If installed in reverse, it will affect the effect and life (such as throttle), or not at all. (such as pressure reducing valves), even causing danger (such as check valves). Generally brass valves have a directional mark on the valve body; if not, they should be correctly identified according to the working principle of the brass valve. The valve chamber of the stop valve is asymmetrical to the left and right, and the fluid should be passed from bottom to top through the valve port, so that the fluid resistance is small (determined by the shape), the labor is turned on (because the medium pressure is upward), and the medium is not pressed after the closing, which is convenient for maintenance. This is why the stop valve can't be reversed. Other brass valves also have their own characteristics.
The installation position of the brass valve must be convenient for operation: even if the installation is temporarily difficult, it is necessary for the long-term work of the operator. It is best to use the brass valve handwheel with the chest (usually 1.2 meters from the operating floor), so that opening and closing the brass valve is more labor-saving. The floor brass valve hand wheel should be facing up, do not tilt, so as to avoid awkward operation. The brass valve of the equipment against the wall should also leave room for the operator to stand. It is necessary to avoid the operation of the sky, especially acid and alkali, toxic media, etc., otherwise it is very unsafe. Do not flip the gate (ie, the handwheel is down), otherwise the medium will remain in the bonnet space for a long time, which will easily corrode the valve stem and is contraindicated for certain process requirements. It is inconvenient to replace the packing at the same time Open the gate valve, do not install it in the ground, otherwise the exposed valve stem will be corroded due to moisture. Lifting check valve, the valve flap should be vertical when installing, so that the lifting is flexible. Swing-type check valve, to ensure the level of its pin when installing, so that the swing is flexible. The pressure relief valve should be installed upright on a horizontal pipe and not tilted in all directions.
2. Construction operations
Care must be taken during installation and construction. Do not strike brass valves made of brittle materials.
Prior to installation, the brass valve should be inspected and the model number checked for damage, especially for the valve stem. Also turn a few times to see if it is skewed, because it is most likely to hit the valve stem during transportation. Also remove debris from the valve.
When the brass valve is lifted, the rope should not be attached to the handwheel or the valve stem to avoid damage to these parts and should be attached to the flange.
For pipes connected to brass valves, be sure to clean them. Compressed air can be used to blow off iron oxide chips, mud sand, welding slag and other debris. These debris not only easily scratch the sealing surface of the brass valve, but also large particles (such as welding slag) can also block the small brass valve and make it invalid. When installing the screw brass valve, the sealing packing (line hemp aluminum oil or Teflon raw material tape) should be wrapped on the pipe thread, not in the brass valve, so as to avoid the valve memory and affect the medium circulation.
When installing flanged brass valves, be careful to tighten the bolts symmetrically and evenly. The brass valve flange and the pipe flange must be parallel and the clearance is reasonable to avoid excessive pressure or even cracking of the brass valve. Pay particular attention to brittle valves and brass valves that are not strong enough. Brass valves to be welded to the pipe shall be spot welded first, then the closure shall be fully opened and then welded.
(3) Protective measures
Some brass valves also require external protection, which is insulation and cold preservation. Hot steam lines are sometimes added to the insulation layer. What kind of brass valve should be insulated or kept cold, depending on the production requirements.
In principle, if the medium in the valve reduces the temperature too much, it will affect the production efficiency or freeze the brass valve, so it needs to be insulated or even mixed with heat; when the brass valve is exposed, it is unfavorable to production or causes frost and other undesirable phenomena. It needs to be cold. Insulation materials are asbestos, slag cotton, glass wool, perlite, diatomaceous earth, vermiculite, etc.; cold insulation materials are cork, perlite, foam, plastic and so on.
(4) Bypass and instrument
Some brass valves, in addition to the necessary protective facilities, also have bypass and instrumentation. A bypass is installed. Easy to repair the trap. Other brass valves are also installed with bypass. Whether to install the bypass depends on the condition of the brass valve, the importance and the requirements of the production.
(5) Filler replacement
Brass valves in stock, some fillers are not good, and some do not match the medium used, which requires replacement of the filler. Brass valve manufacturers can not consider the use of different mediums of thousands of units, the packing box is always filled with ordinary packing, but when used, the packing must be adapted to the medium.
When replacing the packing, press it in a circle. The seam is preferably 45 degrees per turn, and the circle and the ring are opened 180 degrees. The height of the packing should consider the room for the gland to continue to be compacted. At present, the packing chamber should be pressed to the appropriate depth of the packing chamber. This depth can generally be 10-20% of the total depth of the packing chamber. For brass valves with high requirements, the joint angle is 30 degrees. The seam between the circle and the circle is staggered by 120 degrees. In addition to the above fillers, rubber O-rings can be used according to the specific conditions (natural rubber is resistant to weak alkali below 60 degrees Celsius, nitrile rubber is resistant to oil crystals below 80 degrees Celsius, and fluororubber is resistant to various corrosive media below 150 degrees Celsius) Formed packings such as a stack of PTFE rings (resistant to strong corrosive media below 200 degrees Celsius), nylon bowl rings (resistant to 120 degrees Celsius, ammonia, alkali). On the outside of the ordinary asbestos packing, a layer of Teflon raw material tape is wrapped to improve the sealing effect and reduce the electrochemical corrosion of the valve stem.
When pressing the seasoning, turn the valve stem at the same time to keep the circumference evenly and prevent it from being too dead. To tighten the gland, apply even force and not tilt.
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