The Difference between Internal Leakage and External Leakage of Valve

In daily use of valve, we will encounter all kinds of failures. The leakage of the valve is the most common in various failures. The leakage of valve can be divided into internal leakage and external leakage. Then, what’s the difference between these two?

The internal leakage of the valve refers to the situation in which there’s still medium leaking from the flow channel after the sanitary valve is fully closed. To put it simply, it’s the inability to be tightly closed and poor sealing. This failure is usually caused by the corrosion of the medium or impurities. Even if the valve stem is fully tightened, since there’s still gap between valve core and valve body, the medium can still flow through.

The external leakage of the valve refers to the situation in which there’s leakage of the medium at the external sealing part of the stuffing after the valve is fully closed or opened. This failure can be caused by the following reasons: sealing between valve and the connecting flange or thread is not tight, leading to medium leaking from sealing surface; the sealing between valve stem and valve cover is not tight, leading to medium leakage; corrosion of the medium, leading to the wear of the valve body.