Analysis of Steam Valve Leakage due to Sealing

The sealing damage of the steam trap valve is the main cause of internal leakage of the valve. There are many reasons for valve sealing failure, among which the failure of the sealing pair composed of the valve core and valve seat is the main reason.

There are many reasons that affect the damage of the valve sealing surface, including mechanical wear caused by incorrect selection, high-speed erosion, medium cavitation, various corrosion, blockage of impurities, improper selection of valve core and seat materials, deformation of the sealing pair caused by heat treatment process and water hammer, etc.

1. Electrochemical erosion. Due to factors such as mutual contact between sealing surfaces, contact between sealing surfaces and the sealing body and valve body, as well as differences in medium concentration and oxygen concentration, potential differences can occur, leading to electrochemical erosion and erosion of the sealing surface on the anode side.

2. Erosion and cavitation of the medium. It is the result of wear, flushing, and cavitation of the sealing surface during the activity of the medium. At a certain speed, the floating fine particles in the medium collide with the sealing surface, causing local damage. When the medium is mixed and partially vaporized, bubbles explode and impact the sealing surface, causing local damage.

3. Damage caused by improper selection and poor handling. The main manifestation is that the valve was not selected according to the working conditions, and the block valve was used as a throttle valve, resulting in excessive sealing pressure, fast sealing or lax sealing, and causing erosion and wear on the sealing surface.

4. The processing quality of the sealing surface is poor. The main manifestation is cracks, pores, and slag inclusions on the sealing surface, which are caused by improper selection of welding and heat treatment specifications, as well as poor handling during the welding and heat treatment process.

5. Incorrect installation and improper maintenance. Due to these reasons, there are also many abnormal phenomena in the sealing surface, such as valve operation with defects and premature damage to the sealing surface. Sometimes rough operation and excessive closing force are also the reasons for sealing surface failure.

6. Blockage of impurities. The welding slag and excess gasket material that have not been cleaned after welding the steam pipeline, as well as the scaling that has fallen off from the steam system, are all sources of impurities.

The causes of sealing surface damage can be summarized as two types: human damage and application damage. Human damage is caused by factors such as poor design, poor manufacturing, improper material selection, improper installation, poor use, and poor maintenance. Application damage refers to the wear and tear of the valve under normal working conditions, which is caused by the inevitable erosion and erosion of the sealing surface by the medium. Proper prevention of damage can reduce losses and extend service life.