Damage to valve sealing surfaces is typically the result of multiple contributing factors, including material selection, operating conditions, operating practices, and maintenance. The following is a categorized summary of the most common causes:

1. Mechanical Damage

●  Wear: Solid particles in the medium (such as sand or welding slag) erode the sealing surface, resulting in scratches or grooves.

●  Abrasive scuffing: Frictional wear caused by relative movement of the sealing surfaces during valve opening and closing, particularly in metal-to-metal sealing pairs.

●  Impact damage: Deformation of the sealing surface caused by high-velocity fluid impingement or rapid valve opening and closing, leading to impact loading.

2. Chemical Corrosion

● Media corrosion: Acidic, alkaline, or oxidizing media directly attack the sealing surface material, such as metal corrosion caused by H₂S or chloride ions.

● Electrochemical corrosion: When sealing pairs made of dissimilar metals are exposed to an electrolyte, galvanic corrosion may occur due to electrochemical cell formation.

● Erosion–corrosion: The combined effect of corrosive media and high-velocity flow accelerates material loss on the sealing surface.

3. Thermal Damage

●Thermal fatigue:Frequent temperature fluctuations cause repeated thermal expansion and contraction of the sealing surface, leading to cracking or deformation.

●High-temperature oxidation:At elevated temperatures, the sealing surface may undergo oxidation, hardening, or burn-off, as commonly observed in steam valve applications.

●Thermal shock:Sudden exposure to high- or low-temperature media can cause cracking of the sealing surface, such as during rapid condensation or cold media ingress.

4. Improper Installation and Operation

●Installation misalignment: Incorrect valve installation or excessive piping stress can result in uneven loading on the sealing surfaces.

●Over-tightening: Excessive preload applied to the valve stem or bolting may crush or deform the sealing surface, particularly in soft-seated valves or soft sealing gaskets.

●Rough operation: Rapid opening and closing or excessive operating force can cause impact damage to the sealing surfaces.

5. Material Defects

●Improper material selection: The sealing surface material lacks sufficient resistance to process media, high temperature, or wear, such as the use of carbon steel in acidic service.

●Manufacturing defects: Defects in the hardfacing or overlay layer, including porosity, slag inclusions, or improper heat treatment, reduce wear resistance and overall sealing performance.

6. Abnormal Operating Conditions

●Cavitation / flashing: Pressure fluctuations in the fluid generate vapor bubbles that collapse and impact the sealing surface, a phenomenon commonly observed in valves installed downstream of pumps.

●Scaling / deposition: Impurities in the medium accumulate on the sealing surface, impairing tight shutoff, such as calcium scale or polymer deposits.

7. Inadequate Maintenance

●Insufficient lubrication: Seizing or increased friction of the valve stem or drive components prevents proper contact of the sealing surfaces.

●Lack of periodic inspection: Minor damage is not detected or addressed in time, allowing it to propagate into extensive sealing surface failure.

●Improper cleaning: Foreign materials left behind during maintenance, such as tool-induced scratches or residual welding slag, damage the sealing surfaces.

Preventive Measures

●Appropriate material selection: Choose corrosion- and wear-resistant materials based on the characteristics of the process medium, such as stainless steel, hard alloys, or ceramics.

●Standardized operation: Avoid rapid valve opening and closing, control valve travel, and minimize water hammer effects.

●Regular maintenance: Clean pipeline contaminants, lubricate moving components, and replace aging sealing elements.

●Operating condition monitoring: Monitor temperature and pressure fluctuations to prevent overpressure or overheating.

Through a comprehensive analysis of specific operating conditions and observed damage patterns, valve design, operation, and maintenance strategies can be optimized to extend the service life of sealing surfaces.