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日期: 2019-03-20

General requirements for valves and pipes

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General requirements for valves and pipes


1. When the outlet diameter of fire pump is greater than 300 mm, the valve with single manual opening and closing function should not be used. Valves should have clear opening and closing signs, remote control valves should have fast opening and closing function, and reliable sealing. Chinese style


2. Locking devices shall be installed for normally open or normally closed valves, and opening and closing indicators shall be installed for control valves and valves requiring opening and closing. The opening and closing signals of the control valves participating in the linkage control of the remote control gun system shall be transmitted to the system control room. Chinese style


3. Ball valves shall be used on dry powder pipelines, and their diameters must be the same as the inner diameters of pipelines. Chinese style


4. Pipelines should be made of corrosion-resistant materials or treated with corrosion-resistant materials. Chinese style


5, suitable flushing interface should be provided in the proper position of foam liquid, foam mixture or seawater pipeline. An automatic exhaust valve shall be installed at the top of the pipe section where air may be retained. Chinese style


6, after the foam mixing device, a bypass test interface should be set up.


General Requirements for Common Materials of National Standard Valves


1) Material for valve body, bonnet and flange shall be selected according to service conditions and manufacturing requirements, and shall comply with the requirements of GB 12228, GB 12229, GB 12230 and GB 3077.


2) Bolts and studs can be made of A5, 25, 35, 30CrMoA and 40MnVB. They should be selected according to the operating pressure and temperature, and conform to the requirements of GB 700, GB 699 and GB 3077.


3) Nuts can be made of A3, 20, 30, 35, 45, 3030CrMoA and 40MnVB. They should be selected according to the pressure and temperature, and conform to the requirements of GB 700, GB 699 and GB 3077.


4) Precision castings shall not be used for valves with nominal pressure PN > 10.0 MPa.


5) Care should be taken of the possibility of graphitization in the following situations:


a.碳素钢约高于425℃时;


B. Carbon-molybdenum steel is higher than 470 C.


C. When the chromium-molybdenum steel (containing less than 0.6% chromium) is higher than 525 C.


6) Attention should be paid to possible peroxide reactions (oxidizing skin) in the following situations:


A. 1Cr-0.5Mo steel, 1.25Cr-0.5Mo steel, 2Cr-1Mo steel and 3Cr-1Mo steel above 565 C;


B. 5Cr-0.5Mo steel above 595 C.


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