What is the selection principle of high pressure needle valve?
Selection principle of ultra high pressure needle valve:
1. Low temperature needle valve with high pressure needle valve cover should be selected for pipeline system and device with low temperature medium.
2. The lifting rod type needle valve can be used in the pipeline system of the catalytic cracking unit of the oil refining unit.
3. The stainless steel needle valve made of austenitic stainless steel and polytetrafluoroethylene as the valve seat sealing ring should be selected in the device and pipeline system of corrosive medium such as acid and alkali in chemical system.
4. Metal sealed needle valve can be used in piping system or device of high temperature medium in metallurgical system, electric power system, petrochemical plant and urban heating system.
5. The needle valve connected by welding shall be selected for the delivery pipeline and storage equipment of product oil.
6. On the pipeline of city gas and natural gas, the needle valve with flange connection and internal thread connection is selected.
7. In the oxygen pipeline system, it is necessary to degrease strictly.
Precautions for installation of ultra high pressure needle valve:
1. The installation position, height, inlet and outlet direction must meet the design requirements. The direction of medium flow should be consistent with the arrow direction marked on the valve body, and the connection should be firm and tight.
2. The appearance inspection must be carried out before the installation of high-pressure needle valve, and the valve name plate shall meet the provisions of current national standards.
3. For the valve with working pressure greater than 32.0 MPa and cut-off effect on the main pipe, strength and tightness test shall be conducted before installation, and the valve can be used only after passing the test.
4. In the strength test, the test pressure is 1.5 times of the nominal pressure, and the duration is not less than 5min. The valve shell and packing are qualified if there is no leakage.
5. In the tightness test, the test pressure is 1.1 times of the nominal pressure
