Valve internal leakage cause identification

Valve internal leakage usually refers to the loose internal seal of the valve, resulting in medium leakage, while external leakage refers to leakage at the interface between the valve and the pipeline. Water leakage or leakage occurs inside the valve, mainly due to the aging and damage of the internal sealing ring of the valve or the loosening of internal parts of the valve, resulting in medium leakage.
In the case of identification of the cause of valve internal leakage, Zhongke Testing can provide identification services of the cause of valve internal leakage.

is classified according to the driving mode: it is divided into driven valves and automatic valves, and the driven valves can be divided into manual valves and power-driven valves.
is classified according to nominal pressure: it is divided into low vacuum valves, medium vacuum valves, high vacuum valves, ultra-high vacuum valves, low-pressure valves, medium-pressure valves, high-pressure valves and ultra-high-pressure valves.
is classified according to nominal size (diameter): it is divided into small diameter valves, medium diameter valves, large diameter valves and extra large diameter valves.
is divided into high temperature valve, medium temperature valve, normal temperature valve, low temperature valve and ultra-low temperature valve according to operating temperature.
is classified according to use and function: divided into cut-off valves, check valves, distribution valves, regulating valves, safety valves, other special valves and multi-purpose valves.

GB/T 12230-2023 General valves Technical specifications for stainless steel castings
GB/T 22137.2-2018 Valve positioners for industrial process control systems Part 2: Intelligent valve positioner performance evaluation methods
GB/T 13927-2022 Industrial valves Pressure test
GB/T 22137.1-2008 Valve positioners for industrial process control systems Part 1: Performance evaluation method for pneumatic output valve positioners
GB/T 19672-2021 Pipeline valves Technical conditions
GB/T 26480-2011 Inspection and testing of valves
GB/T 24925-2019 Cryogenic valves Technical conditions
GB/T 28270-2012 Intelligent valve electric device
GB/T 34878-2017 Vacuum technology valve Leak rate test
GB/T 26481-2022 Emission test of industrial valves
0GB/T 12224-2015 Steel valve General requirements
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was entrusted by a court to conduct physical evidence identification and analysis on the causes of internal and external leakage failure of the valve involved in the case.
quality analysis results: The
quality analysis expert group conducted verification tests and comprehensive analysis based on on-site inspection conditions, laboratory evidence testing data and results, and relevant national standards, and made a comprehensive judgment and made the following suggestions and conclusions:
1. Because the nuts of the bolts used to fix the valve body of the three-piece ball valve involved in the case are missing or loose, it is impossible to know the pretightening force of the fixed valve body and the compression amount of the valve seat. At the same time, the ball valves are all welded and used, which will also cause the deformation of the valve seat. There are no experimental conditions for internal leakage and external leakage, so no judgment will be made.
2, no internal leakage or external leakage was found in the stop valve with model specification XXX;
, the stop valve with model specification XXX does not have external leakage but does have internal leakage. The internal leakage is caused by the roughness of the valve disc sealing surface and the structure of the valve disc sealing surface cannot meet the sealing requirements;
model XXX stop valve does not meet the internal leakage test conditions due to the bending and deformation of the valve stem, and no external leakage was found.