Check valve quality appraisal

check valve refers to a valve whose opening and closing parts are circular valve discs and rely on their own weight and medium pressure to act to block the reverse flow of the medium. They are one of the few automatic valves that do not require assistance to open and close.
check valve is suitable for various media such as liquid, air, steam, condensate, and in some cases liquids containing particles or slurry. It can be used in various industries such as seawater desalination, food and beverage, geothermal, mining, oil and gas, electric power, pulp and paper, and oil refining.
In the case of check valve quality appraisal, Zhongke Testing can provide check valve quality appraisal services.

1. Manufacturing standards The manufacturing of
check valves must comply with national or industry standards, such as GB/T, HG, JB, ANSI and other standards. These standards stipulate the material, size, performance, testing and other requirements for check valves, ensuring the quality and reliability of check valves.
2. Installation position
The installation position of the check valve should be selected reasonably and should usually be installed upstream of the inlet pipe to prevent medium backflow. When its location cannot meet the requirements, piping should be added or the number of check valves should be increased to meet the requirements.
3. Installation dimensions The installation dimensions of
check valve must comply with standard specifications, including installation height, flange standard, connection method, etc. At the same time, the usage conditions of the pipeline, such as pressure, temperature, etc., must also be considered to ensure its reliability and stability.
4. Test standard
During the design and manufacturing process of check valves, strict tests and inspections must be carried out. These tests include strength tests, sealing tests, corrosion resistance tests, etc. The test results must meet the requirements of relevant standards and specifications to ensure the quality and reliability of the check valve.

JB/T 14320-2022 Oxygen check valve
JB/T 13880-2020 Rubber flap check valve
JB/T 13460-2018 Liquefied natural gas axial flow check valve
JB/T 7245-2017 Steel and iron refrigerant stop valves and lifting check valves for refrigeration systems
JB/T 12624-2016 Stop valves and check valves for liquefied natural gas
JB/T 12002-2014 Extraction check valves for steam turbines
JB/T 8937-2010 Wafer check valve
JB 1736-1991 Swing check valve disc seal
JB 1737-1991 Swing check valve disc seal pressure plate

A chemical company purchased a batch of check valves, but after a period of installation and commissioning, three of the valves developed leakage problems. The chemical company communicated with the manufacturer in a timely manner, but the manufacturer failed to find the cause and could not completely solve the problem. So the chemical company asked the manufacturer to return the goods and compensate for the related losses. But the manufacturer did not agree, so the chemical company went to court and asked the court to award compensation to the manufacturer based on the contract matters.
was entrusted by the court to conduct an appraisal and analysis on "whether there are quality problems" with the check valve involved in the case.
appraisal analysis results:
appraisal analysis expert group discussed the relevant information and on-site investigation of the check valve involved and made a comprehensive quality and technical analysis, and made the following suggestions and conclusions:
conducted appraisal on some check valves and found that the main cause of leakage was because the sealing ring material did not meet the regulations. Originally, according to the contract between the two parties, the sealing ring should be PTFE plus graphite, but during the actual inspection, no graphite component was found. Moreover, the material of the sealing ring does not meet the usage conditions stipulated in the contract. If used for normal work, leakage may occur.
In summary, the quality indicators of this batch of check valves do not meet the contract standards of both parties and are considered substandard products.