Detection and quantification of valve stiction

Stiction is a common problem in spring-diaphragm type valves, which are widely used in the process industry. Recently, there have been many attempts to understand, define, model and detect stiction in control valves. Most of the current methods cannot simultaneously detect and quantify stiction. This paper discusses the definition and modelling of stiction. It describes two methods to detect and quantify valve stiction using routine operating data. The methods are completely data-based. No additional excitation or experimentation of the plant is required. The methods have been applied to many industrial data sets and their wide applicability and practicality as useful diagnostic aids in control-loop performance monitoring has been demonstrated