Collecting information
An intelligent control-valve positioner gathers information on the valve performance throughout its lifecycle and during the normal operation. Modern valve controllers store all this data in the device’s own memory. This data can be accessed not only on site, but also remotely. Basically, there is no difference between processing the diagnostics data on-site or from thousands of kilometers away. While remote condition monitoring does not fully replace inspection “footwork” done on-site, it can focus and improve it. Depending on the application, valves should be regularly tested for tightness, condition of valve coatings, etc. These observation results can be stored in the same system together with the valve controller’s diagnostics data and subsequently the valve diagnostics can create a work order to the ERP for a maintenance check.
Neles has several years of experience in condition monitoring and predictive maintenance with customers in different industries. This experience has proven that the amount of information from a site with hundreds of valves equipped with smart positioners can be huge, but it really becomes valuable when used in right way.
Practical example from a safety valve audit on an off-shore platform
The platform had been in operation for only one year before the audit.
Expectations of the audit result were that all safety valves were fully operational, but the result was quite different. Four valves showed needs for immediate repairs and one valve was in such condition that it could not perform the safety action if required. This was indicated by one key performance index, the load factor index, which describes how much available torque of the actuator is used when carrying out PST testing. It is calculated and trended automatically every time PST testing is implemented. This gives crucial information from the plant safety point of view. But, just as important, information for the operational expense point of view was that the remaining 71 ESD valves were operating normally and did not need any maintenance action. This shows the efficiency of PST testing usage and utilization for maintenance planning.
