Manufacture and Installation Requirements for Cryogenic Valves

Installation requirements for cryogenic valves:

Because of the special structure of the cryogenic valve, the installation of a cryogenic valve also has its special requirements. Because of the long neck Valve cover structure, low temperature globe valve must be installed within a 45 degree Angle of the vertical direction of the stem, and should be avoided in the vertical line as far as possible. Otherwise, the low-temperature medium will fill the extension part of the valve cover, resulting in the valve packing failure, and will pass the cold volume to the valve handle, bringing personal injury to the operator. For cryogenic valves with relief structure, when installing the valve, special attention should be paid to the requirements of the relief direction of the valve. The direction of valve pressure relief should be marked on the process flow chart, and reflected in the pipeline axonal diagram (this is extremely important, extremely important, extremely important), if it is necessary to set the pressure relief hole and not set after the valve is closed, the liquid in the valve cavity is heated gasification, easy to cause the body burst. And the direction of pressure relief installed wrong, it may be combustible or toxic process media, leakage to the maintenance side, causing casualties!

Manufacture of a cryogenic valve:

The strict manufacturing processes and special equipment are developed for the low temperature ball valve, and strict quality control is carried out for the processing of parts. After the special low-temperature treatment, the rough parts will be placed in the cooling medium for several hours (2-6 hours) to release the stress, ensure the low-temperature performance of the material, ensure the finishing size, to prevent the valve in the low-temperature working condition, due to the temperature change caused by deformation and leakage. Valve assembly and ordinary valves are also different, the parts need to go through a strict cleaning, remove any oil, in order to ensure the use of performance.

Low Temperature Ball Valve

Cryogenic valve inspection:

In addition to normal temperature and low-temperature tests, cryogenic valves shall be tested as follows

1. The main parts of low temperature steel butterfly valve should be cryogenic (we will have the opportunity to talk about cryogenic treatment later, as shown in the figure below).

2. Low-temperature impact tests should be carried out on main parts and welding seams to ensure that the valve is not brittle in low-temperature working conditions;

3. The valve must be tested at room temperature. Firstly, 1.5 times of nominal pressure and water pressure strength test should be conducted, and then 1.1 times of nominal pressure sealing test should be conducted.

4. After the hydrostatic test, the valve must remove moisture and keep dry without oil;

5. Each batch of cryogenic valves shall be sampled in a certain proportion for the low-temperature test, and the low-temperature test must be conducted after 1.5 times of water pressure strength test.

6. After the low-temperature test of the valve, the air shall be prevented from entering the valve;

7. After the low-temperature test of the valve, the temperature should be raised naturally or by a fan. Heating and other methods to accelerate the temperature rise of the valve are strictly prohibited.

8. Tighten the valve fastener again after the valve temperature test is heated naturally;

9, when the valve storage, must check the valve switch, to ensure that the valve in a reasonable state;

10. During the storage and transportation of the valve, it should be noted that the stainless steel valve should be separated from the carbon steel valve, and it should be dust-proof, water-proof, oil-proof, and bruising-proof.

11. The valve flow direction, pressure relief direction, and nameplate shall be checked according to the requirements of the design unit.