The sealing surface is frequently corroded, eroded, and worn by the medium and is easily damaged because the seal functions as a cutting off and connecting, regulating and distributing, separating, and mixing device for media on the valve channel.

Surface damage can be sealed for two reasons: man-made damage and natural damage. bad design, bad manufacture, inappropriate material selection, wrong installation, poor use, and poor maintenance are some of the causes of damage that is the result of human activity. Natural damage is the wear on the valve that occurs during normal operation and is the result of the medium’s inescapable corrosion and erosive action on the sealing surface.

The reasons for the damage of the sealing surface can be summarized as follows:

1. The sealing surface’s processing quality is poor.

The principal symptoms of it are defects like cracks, pores, and inclusions on the sealing surface, which are brought on by inadequate surfacing welding and heat treatment process operation and unsuitable specification selection. Incorrect material choice has resulted in an excessively high or excessively low level of hardness on the sealing surface. Because the underlying metal is blown to the top during the surfacing process, which dilutes the sealing surface’s alloy composition, the sealing surface’s hardness is uneven and it is not corrosion-resistant, either naturally or as a result of incorrect heat treatment. Undoubtedly, there are also design problems in this.

2. Damage brought on by bad choice and poor performance

The major performance is that the cut-off valve is employed as a throttle valve and that the valve is not chosen for the working conditions, resulting in excessive closing specific pressure and too quick or lax closing, which leads to erosion and wear on the sealing surface.

The sealing surface will operate irregularly as a result of improper installation and careless maintenance, and the valve will run sickly, prematurely damaging the sealing surface.

3. Chemical medium deterioration

In the absence of current generation by the medium around the sealing surface, the medium directly interacts with the sealing surface and corrodes it. The sealing surface on the anode side will corrode due to electrochemical corrosion as well as the contact between the sealing surfaces, the contact between the sealing surface and the closing body and the valve body, the concentration difference of the medium, the oxygen concentration difference, etc.

4. Medium erosion

It occurs when the medium runs across the sealing surface and causes wear, erosion, and cavitation. The floating fine particles in the medium hit with the sealing surface when it reaches a particular speed, resulting in localized damage. Localized damage results from the high-speed flowing media directly scouring the sealing surface. Air bubbles burst and contact the seal surface when the medium is combined and partially evaporated, resulting in localized damage. The sealing surface will be severely eroded by the medium’s erosive activity and the alternate chemical corrosion action.

5. Mechanical harm

Scratches, bruising, squeezes, and other damage to the sealing surface will occur throughout the opening and closing procedure. Under the influence of high temperature and high pressure, atoms enter one another between the two sealing surfaces, causing the adhesion phenomenon. The adhesion is easily torn when the two sealing surfaces move in relation to one another. This phenomenon is more likely to occur if the sealing surface has a higher surface roughness. The sealing surface will become somewhat worn or indented as a result of the valve disc’s bruising and squeezing of the sealing surface when it returns to the valve seat during the closing operation.

6. Wear and tear

The sealing surface will get exhausted over time from the action of alternating loads, leading to the development of cracks and peeling layers. After prolonged usage, rubber and plastics are prone to aging, which impairs performance.

It is clear from the study of the causes of sealing surface damage done above that choosing the right sealing surface materials, suitable sealing structures, and processing techniques is vital to increase the quality and service life of the sealing surface on valves.