Basic mechanism and maintenance of the valve

The opening and closing mechanism is composed of a flap (also called a valve disc, a spool), a valve stem and a driving device (handwheel). The valve stem is screwed onto the valve cover with a trapezoidal thread. The hand wheel and the valve disc are fixed on the upper and lower ends of the valve stem. The hand wheel is rotated, and the valve stem can be raised or lowered to drive the valve flap to close or leave the valve seat to close and When opened, the valve flap is closely matched with the valve seat, and the valve flap is pressed against the valve seat by the pressure of the valve stem. At this time, the valve is completely closed, and the valve is tightly sealed.

 The components of the valve must be processed as follows before assembly:

1. According to the processing requirements, some parts need to be polished, and the surface cannot be processed with burrs;

2. All parts are degreased;

3. After the degreasing is completed, the acid washing passivation is carried out, and the cleaning agent does not contain phosphorus;

4, after pickling and purification, rinse with pure water, there can be no drug residue, carbon steel parts save this step;

5. Dry the parts one by one with a non-woven fabric, and do not leave the surface of the parts such as wire wool, or blow dry with clean nitrogen;

6. Use a non-woven fabric or a precision filter paper to analyze the pure alcohol and wipe each component one by one until there is no dirty color.

 The cleaned parts must be sealed and stored for installation. The specific requirements for the installation process are as follows:

1. The installation workshop must be clean, or set up a temporary clean area, such as the use of newly purchased color strips or plastic film to prevent dust from entering during the installation process.

2, the assembly workers must be dressed in clean cotton overalls, wearing a cotton cap, hair can not leak, wear clean shoes, hands wearing plastic gloves, skim,.

3. The assembly tool must be degreased and cleaned before assembly to ensure cleanliness.

 For other requirements for valves:

1. The assembled valve is purged with nitrogen for at least 1 minute.

2. The airtight test must be pure nitrogen.

3. After the airtight test is passed, encapsulation is carried out, sealed with a clean polyethylene cap, and the polyethylene cap is soaked with an organic solvent before use and wiped clean.

4. Then seal with a vacuum bag.

5, finally packing.

6. Measures should be taken during transportation to ensure that the envelope is not damaged.

7. Acceptance requirements: Acceptance follows HG 20202-2000 “Degreasing Engineering Construction and Acceptance Specification”. Each component is cleaned with clean precision filter paper before assembly. The dead angle of the component is selected, and the color of the filter paper is qualified.