It is widely known that most of the chemical and bio chemical systems are complex in nature due to presence of non-linearity in input-output behaviour or inherent non-linearity of certain accessories, specifically in actuators, like control valves in an industry. The actuators of control systems, i.e., pneumatic control valves play important role in exhibiting complex behaviour that cannot be modelled using simple linear dynamics. With progress in time, the control valves show unusual behaviour between its inputs and outputs mostly due to stiction, hysteresis and dead-band non-linearity. Experimental results on several control valves show continuous degradation in loop performances. A theoretical model based on statistical analysis of steady state data of manipulated variable (MV) is formulated to predict maintenance requirement around the control loop. The theoretical model is validated using experimental data obtained from particular process industry.