Installation requirements

1. Before valve installation, carefully check whether the model and specification of the valve used are consistent with the design;

2. Check whether the valve can be used under the required conditions according to the valve model and factory instructions;

3. When hoisting the valve, the rope shall be tied to the flange connection of the valve body and bonnet, and shall not be tied to the handwheel or valve stem to avoid damaging the valve stem and handwheel;

4. When installing the valve on the horizontal pipeline, the valve rod shall be vertically upward, and it is not allowed to install the valve rod downward;

5. When installing the valve, it is not allowed to use the forced butt connection mode of drag and pull to avoid damage due to uneven stress;

6. The rising stem gate valve should not be installed in the underground wet place to avoid corrosion of the valve stem.

Assembly requirements

The cleaned parts must be sealed and stored for installation.

Requirements for the installation process are as follows:

1. The installation workshop must be clean, or a temporary clean area must be built, such as newly purchased color strip cloth or plastic film, to prevent dust from entering during installation.

2. Assemblers must wear clean cotton overalls, cotton hats, clean shoes, plastic gloves and degrease.

3. Tools for assembly must be degreased and cleaned before assembly to ensure cleanliness.

Acceptance requirements

The acceptance shall comply with HG 20202-2000 Code for Construction and Acceptance of Degreasing Engineering. Before assembly, each part shall be wiped with clean precision filter paper, and the dead corner of the part shall be selected. If the color of the filter paper does not change, it is qualified.

Valve specification requirements

1. The model of the valve shall indicate the national standard number requirements. If it is an enterprise standard, the relevant description of the model shall be indicated.

2. The working pressure of the valve shall be ≥ the working pressure of the pipeline. On the premise of not affecting the price, the working pressure that the valve can bear shall be greater than the actual working pressure of the pipeline.

3. The manufacturing standard of valves shall state the national standard number. If it is an enterprise standard, the purchase contract shall be attached with enterprise documents.

Performance test requirements

1. When a certain specification of valve is manufactured in batches, an official organization shall be entrusted to carry out the following performance tests: ① the opening and closing torque of the valve under the working pressure; ② Detection of flow resistance coefficient of valve under pipeline water delivery condition.

2. The following tests shall be carried out for the valve before delivery: ① When the valve is open, the valve body shall withstand the internal pressure test of twice the working pressure value of the valve; ② When the valve is closed, both sides bear 11 times of the valve pressure value respectively, without leakage; However, the leakage value of metal sealed butterfly valve shall not exceed relevant requirements.

      Sealing requirements

      The sealing performance of the valve refers to the ability of each sealing part of the valve to prevent medium leakage, which is the most important technical performance index of the valve. There are three sealing parts of the valve: the contact between the opening and closing parts and the two sealing surfaces of the valve seat; The fitting place of packing, valve stem and stuffing box; Connection between valve body and bonnet. The leakage at the first place is called internal leakage, that is, it is usually said that the valve is not tightly closed, which will affect the ability of the valve to cut off the medium. For block valves, internal leakage is not allowed. The latter two leaks are called external leakage, that is, the medium leaks from the valve to the outside. Leakage will cause material loss, environmental pollution, and even accidents in serious cases. For flammable, explosive, toxic or radioactive media, leakage is not allowed, so the valve must have reliable sealing performance.

      Other requirements

1. Purge the assembled valve with nitrogen for at least 1 minute.

2. The airtight test must be conducted with pure nitrogen.

3. Encapsulation shall be carried out after the air tightness test is qualified, and the polyethylene cap shall be sealed with a clean polyethylene cap. Before use, the polyethylene cap shall be soaked with organic solvent and wiped clean.

4. Then seal with a vacuum bag.

5. Final packing.

6. During transportation, measures shall be taken to ensure that the package is not damaged.