Valve installation instruction manual Installation and maintenance of corrosion-resistant fluorine lined valve
Low temperature valves are installed at atmospheric temperature. In practical application, when the medium passes through, it becomes a low temperature state. Due to the formation of temperature difference, flanges, gaskets, bolts and nuts, etc., shrink, and because the materials of these parts are not the same, their linear expansion coefficient is also different, forming a very easy to leak environmental conditions. From this objective situation, when tightening bolts at atmospheric temperature, the torque that takes into account the contraction factors of each component at low temperature must be adopted.
1. Installation and disassembly of valves
1.1 Precautions for maintenance and Installation
1). The valve should be placed in a dry and ventilated room, and both ends of the diameter should be sealed and dustproof;
2). Long-term storage should be inspected regularly, and the processing surface should be coated with oil to prevent corrosion;
3) Before valve installation, carefully check whether the mark is in accordance with the use requirements;
4). During installation, the inner cavity and sealing surface should be cleaned, and the packing should be checked to see whether it is pressed tightly, and the connecting bolts should be tightened evenly.
5). The valve should be installed in accordance with the allowable working position, but attention should be paid to maintenance and convenient operation;
6) In use, do not partially open the gate valve to adjust the flow rate, so as not to damage the sealing surface when the medium flow rate is high, it should be fully open or fully closed;
7). When turning the handwheel on or off, do not use other auxiliary levers;
8). Transmission parts should be lubricated regularly; The valve should always be oiled in the rotating part and the stem trapezoidal thread part
9) After installation, regular maintenance should be carried out to clear the dirt in the inner cavity, check the sealing surface and the wear of the valve stem nut;
10). There should be a set of scientific and correct installation standards, sealing performance test should be carried out in maintenance, and detailed records should be made for investigation
11) Other matters needing attention:
1) Valves should generally be positioned before pipeline installation. The pipe should be natural, the position is not hard pull, so as not to leave the prestress;
2) Before positioning the low temperature valve should be as far as possible in the cold state (such as in liquid nitrogen) to do the opening and closing test, flexible and no jamming phenomenon;
3) The liquid valve should be configured with a 10° tilt Angle between the stem and the level to avoid liquid flowing out along the stem and increase the cold loss; More importantly, it is necessary to avoid the liquid touching the sealing surface of the packing, so that it is cold and hard and loses the sealing effect, resulting in leakage;
4) the connection of the safety valve should be elbow to avoid direct impact on the valve; In addition to ensure that the safety valve does not frost, so as not to work failure;
5) the installation of the globe valve should make the medium flow direction consistent with the arrow marked on the valve body, so that the pressure on the valve top cone when the valve is closed, and the packing is not under load. But not often open and close and need to strictly ensure that in the closed state does not leak the valve (such as heating valve), can be consciously reversed, with the help of medium pressure to make it closed;
6) large specifications of gate valve, pneumatic control valve should be installed vertically, so as not to bias one side due to the weight of the spool, increase the mechanical wear between the spool and the bushing, resulting in leakage;
7) When tightening the pressing screw, the valve should be in a slightly open state, so as not to damage the sealing surface of the valve top;
8) After all valves are in place, they should be opened and closed again, and qualified if they are flexible and not stuck;
9) After the large air separation tower is cooled bare, the connecting valve flange is pre-tightened once in the cold state to prevent leakage at room temperature and leakage at low temperature;
10) It is strictly prohibited to climb the valve stem as a scaffold during installation
11) The high temperature valve above 200℃, because the installation is at room temperature, and after normal use, the temperature rises, the bolt is thermal expansion, the gap is increased, so it must be tightened again, called “hot tight”, the operator should pay attention to this work, otherwise it is easy to leak.
12) When the weather is cold and the water valve is closed for a long time, the water behind the valve should be removed. After the steam valve stops steam, the condensed water should also be excluded. The bottom of the valve acts as a wire plug, which can be opened to drain water.
13) Non-metallic valves, some hard brittle, some low strength, operation, opening and closing force can not be too large, especially can not make strong. Also pay attention to avoid object bump.
14) When the new valve is used, the packing should not be pressed too tightly to avoid leakage, so as to avoid too much pressure on the stem, accelerate wear, and open and close.
Corrosion resistance Fluorine lining valve installation and maintenance The corrosion resistance valve and pipeline accessories of the lining, due to their inherent physical and chemical properties, have the following characteristics in the installation, repair and maintenance of the product: Terminology and description
(a) The full lining type generally refers to the inner wall of the valve body, valve cover and other pressure parts directly in contact with the medium. The outer surface of the valve stem, butterfly plate, cock and sphere and other inner parts is coated with a certain thickness of plastic corrosion resistant valve by the method of molding. The commonly used materials are F46, F3, F2, etc. Fluorine lined valve is a kind of valve parts commonly used in industry, it still has a variety of different classification, fluorine lined valve lining material according to different pipeline different valve material (anticorrosive material), let’s introduce it in detail for you.
Corrosion resistance fluorine lining valve installation and maintenance of fluorine lining valve what are the materials
1, polyene diameter PO
Applicable medium: various concentrations of acid and alkali salts and some organic solvents. Operating temperature: -58-80 degrees Celsius.
Features: It is an ideal anticorROsive material in the world. It has been widely used in the lining of large equipment and pipe parts.
2, polyperfluoroethylene propylene FEP(F46)
Applicable medium: any organic solvent, dilute or concentrated inorganic acid, alkali, etc., temperature: -50-120 degrees Celsius.
Features: MECHANICAL, ELECTRICAL PROPERTIES AND CHEMICAL STABILITY ARE BASICALLY THE SAME AS F4, BUT THE outstanding ADVANTAGES ARE high dynamic toughness, excellent weather resistance and radiation.
3. Polytrifluoride PCTEF(F3)
Applicable medium: various organic solvents, inorganic corrosion liquid (oxidizing acid), temperature: -195-120 degrees Celsius.
Features: Heat resistance, electrical properties and chemical stability is inferior to F4, mechanical strength, hardness is better than F4.
4, PTFE(F4)
Applicable medium: strong acid, strong base, strong oxidant, etc. Use temperature -50-150 degrees Celsius.
Features: Excellent chemical stability, high heat resistance, cold resistance, low friction coefficient, is an excellent self-lubricating material, but low mechanical properties, poor fluidity, large thermal expansion.
5. Polypropylene RPP
Applicable medium: aqueous solution of inorganic salts, dilute or concentrated melting liquid of inorganic acids and alkalis. Operating temperature: -14-80 degrees Celsius.
Features: One of the light plastics for its yield. Tensile and compressive strength, hardness are excellent with low pressure polyethylene, has a very outstanding rigidity; Good heat resistance, easy molding, after the modification of the excellent cheap, the motility, fluidity and elastic modulus of bending are improved.
6, polyvinylidene fluoride PVDF(F2)
Suitable medium: Resistant to most chemicals and solvents. Use temperature -70-100 degrees Celsius.
Features: TENSILE STRENGTH AND COMPRESSION STRENGTH THAN F4, bending resistance, weather resistance, radiation resistance, light resistance and aging, etc., is characterized by good toughness, easy molding.
Post time: Sep-14-2022
