Technical requirements for installation of liquid ammonia stop valve
Time: September 2, 2020 14:04:07 Source: Yonglong Valve Reading: zero second
Technical requirements for installation of liquid ammonia stop valve
The liquid ammonia valve installation of technical requirements
Liquid ammonia stop valve is also called Ammonia stop valve Before installation of ammonia stop valve, check whether all parts of the valve are in good condition, whether the opening and closing valve can rotate freely, whether the sealing surface is damaged, etc., clean the impurities in the valve chamber, after confirmation, the valve can be installed after the pressure test is qualified. The installation quality of the liquid ammonia stop valve will directly affect the use of the valve in the future. Therefore, the construction unit and the production unit should attach great importance to it.
1. Directionality. The valve body of the liquid ammonia stop valve is marked, and the direction indicated by the arrow is the direction in which the output flows forward. The installation position of some liquid ammonia stop valves has special requirements. When installing in the opposite direction, the medium is from top to bottom. The online replacement of valve stem sealing packing must be carried out in the fully open state.
2. Installation position. In consideration of long-term operation and maintenance of the valve, it is necessary to make operation and maintenance as convenient as possible. At the same time, attention should be paid to the beautiful appearance during assembly. The valve handle can be vertically upward, or tilted to a certain angle or placed horizontally, but the hand wheel should not be downward to avoid upward facing operation.
3. Screw thread liquid ammonia stop valve, remove the excessive grease and sundries from the cover of the threaded port and the thread, and check the sealing performance of the threaded liquid ammonia stop valve. During installation, attention must be paid to proper force. Pipe tongs or wrenches of different specifications shall be selected according to the size of ammonia valve. During installation, the valve company shall ensure that the thread is intact; Timely wrench that can be used instead of pipe wrench to avoid damaging the appearance of valve body.
4. The installation of the special stop valve for flange liquid ammonia must ensure that the cross sections of the two flanges are parallel to each other and on the same axis. When tightening the bolts, it should be carried out in a crisscross manner to make the valve end face evenly stressed.
5. Flanged and threaded valves shall be installed in closed state. When the butt welding valve is connected with the pipeline, the bottom of the weld should be welded by argon welding to ensure the internal cleanness. When welding, the valve should not be closed to prevent thermal deformation.
6. When lifting the valve, the rope shall not be tied to the first wheel or valve stem to prevent damage. It shall be lifted and placed gently without collision. When it is placed on the buttress, it shall be padded steadily and flatly according to the required elevation. There must be firm buttress or support under the valve to hold the valve, and the valve is not allowed to be suspended to generate stress.
The liquid ammonia valve must be visually inspected before installation, and the nameplate of the valve shall comply with the provisions of the current national standard General Valve Marks (GB 12220). For valves whose working pressure is greater than 1.0 MPa and which can cut off the main pipe, strength and tightness tests shall be carried out before installation, and they can only be used after being qualified. During the strength test, the test pressure shall be 1.5 times of the nominal pressure, and the duration shall not be less than 5min. The valve shell and packing shall be qualified if there is no leakage. During the leak test, the test pressure is 1.1 times of the nominal pressure; The duration of the test meets the requirements of GB 50243.
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