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How to Judge Whether the Valve is Internal Leakage or External Leakage?

Feb. 20, 2021

As a Wellhead Equipment Manufacturers, share with you.

In the daily use of valves, various failures are often encountered. Valve leakage is the most common one of many failures, and valve leakage generally includes internal leakage and external leakage! So, what is the difference between the two?

Wellhead Gate Valve

Wellhead Gate Valve

The internal leakage of the valve generally refers to the situation that the medium is still flowing out, leaking or dripping from the flow diameter outlet of the valve after the valve is completely closed. In layman's terms, it is not tightly closed and the seal is not good! The cause of this failure is usually due to the erosion and wear of the medium or the inclusion of impurities. Even if the valve screw is tightened in place, since there is still a gap between the valve core and the valve body, the medium can still flow through.

How to judge whether the valve is internal leakage or external leakage?

The external leakage of the valve generally refers to the leakage of the medium in the external sealing part of the valve packing after the valve is completely closed or opened. That is, between the valve and the connecting flange or connecting thread, the sealing is not tight, which causes the medium to flow out of the connecting sealing surface, or the medium leakage caused by the weak sealing between the valve stem and the gland (ie the gland on the valve stem) , Or external leakage caused by trachoma on the valve body blank, and external leakage caused by the wear of the valve body due to medium erosion.

Installation points

1) The installation position, height, and direction of import and export must meet the design requirements, and the connection should be firm and tight.

2) All kinds of manual valves installed on the thermal insulation pipeline must not handle downwards.

3) Visual inspection must be carried out before valve installation. For valves with a working pressure greater than 1.0 MPa and a cut-off function on the main pipe, the strength and tightness performance test shall be carried out before installation, and the valve shall be used only after being qualified. During the strength test, the test pressure is 1.5 times the nominal pressure, and the duration is not less than 5 min. The valve housing and packing should be qualified without leakage. During the tightness test, the test pressure is 1.1 times the nominal pressure

4) The hand wheel, handle and transmission mechanism are not allowed to be used for lifting, and collision is strictly prohibited.

5) The gate valve with transmission mechanism should be installed according to the product manual.

Our company also sells Wellhead Gate Valve, please contact us.

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