Lined valves are engineered to withstand highly corrosive media, yet failures can still occur when application parameters are misunderstood or installation practices are poor. Understanding the common failure modes helps maintenance teams extend service life and avoid unplanned shutdowns.
One frequent issue is lining permeation. Certain acids and solvents gradually penetrate fluoropolymer layers, reaching the metal body underneath. This leads to blistering or corrosion behind the lining. Selecting the correct grade—such as high-density PFA instead of standard PTFE—significantly reduces this risk. Proper venting of the valve body is also essential.
Cold flow deformation is another challenge, especially in high-temperature services. PTFE tends to creep under continuous stress, which can affect seat tightness and torque. Modern valves use reinforced seats and controlled compression designs to counter this effect. Operators should avoid over-tightening flanges that can distort the lining.
Improper installation contributes to many early failures. Welding near installed lined valves can damage the fluoropolymer. Likewise, misaligned piping introduces mechanical stress that cracks the lining. Best practice recommends flexible expansion joints and careful torque control during bolting.
In slurry or semi-abrasive applications, erosion of the lining may occur. Standard PTFE is not ideal here; PVDF or specially filled grades perform better. Understanding media characteristics before purchase is therefore crucial.
Operational habits also matter. Rapid opening and closing can create pressure surges, lifting the lining from the body. Gradual actuation and correctly sized actuators protect the valve internals.
Routine inspection, spark testing during shutdowns, and genuine spare parts help detect issues early. Most failures are not due to poor product quality but to mismatched application or handling. With correct engineering support, lined valves can deliver decades of trouble-free service even in the harshest chemical environments.
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