Valve Problems and Failure Symptoms
Begin with the observed symptom, then review possible mechanisms, missing operating facts, and the checks needed before selecting a corrective route.
Diagnose before changing the valve
Published references are grouped by the primary problem they help investigate and counted once by canonical URL.
Symptoms are not diagnoses
Noise, leakage, vibration, impact, corrosion, and wear can have system, installation, material, or valve causes that require confirmation.