Causes of Valve Sealing Surface Damage

Common damage factors include improper installation/maintenance, mechanical injury, substandard processing quality, medium erosion, electrochemical corrosion, and chemical corrosion. These can be broadly categorized into ‌artificial damage‌ and ‌natural damage‌.

‌Artificial damage‌ refers to defects caused by poor design, substandard manufacturing, improper material selection, inaccurate installation, incorrect operation, or inadequate maintenance.

‌Installation/maintenance failures‌ lead to abnormal sealing surface operation, causing valves to operate with defects and accelerating premature sealing surface damage.

‌Improper selection or operation‌: Using shut-off valves as throttle valves results in excessive closing-specific pressure, rapid/insufficient closure, causing erosion and wear on sealing surfaces.

‌Substandard processing quality‌: Cracks, pores, or slag inclusions on sealing surfaces due to non-compliant hardfacing/heat treatment specifications or operational errors; uneven hardness or corrosion resistance issues from material/heat treatment mismatches; potential design flaws.

‌Mechanical damage‌ occurs during opening/closing cycles:

Surface scratches, impacts, or crushing.

Atomic interpenetration under high temperature/pressure causes adhesion. Higher surface roughness intensifies this phenomenon.

Local wear or indentations during valve closure or disc reseating.

‌Natural damage‌ arises from unavoidable medium erosion/corrosion during normal operation:

‌Medium erosion‌: Wear, flushing, and cavitation from fluid flow. High-speed media directly erode surfaces, while combined chemical corrosion exacerbates damage.

‌Electrochemical corrosion‌: Potential differences generated by contact between sealing surfaces, closures, valve bodies, or medium concentration/oxygen gradients lead to anodic corrosion.