Condition Monitoring of Safety Critical Valves

Abstract

The oil and gas industry is constantly trying to improve the quality of its operations. The industrial collaboration project, TAIL I/O, focused on this issue by developing and demonstrating technology, methods and work processes related to the monitoring of conditions and performance to ensure optimal performance and maintenance of critical assets.

One of the areas the project wanted to highlight was condition monitoring of safety critical valves. Regulations and company policies require the utmost reliability for safety critical valves. In order to comply with this, valves are given much attention in a facility’s maintenance planning. The challenge is to improve the efficiency of the condition monitoring methods, thus decreasing maintenance costs and increasing operation safety.

The work presented in this thesis has made an overview of the available condition monitoring methods. Potential areas of improvement were discovered and considered for further development. It was decided to set up experiments and gather data with the use of various sensor technologies and analysis methods. The experiments were focused on detecting internal leakage through a damaged closed valve. Furthermore, the data was analyzed with a special emphasis on spectral information developed from the collected data. Spectral data is often used for rotating equipment, but not for static equipment. A new and improved method for estimating the through leak of the valve is presented. And finally, suggestions are made for an approach to introducing the methodology developed into practical use in the industry.

The thesis work falls within three main research questions:

RQ1 What are the current condition monitoring methods used on valves in the industry today, and what are their qualities?

RQ2 Is there potential for improvement of the condition monitoring methods? 

RQ3 How can improved condition monitoring methods be implemented in a best practice scheme?

The primary contributions are:

C1 Conducted a literary survey of condition monitoring methods for valves.

C2 Presented new experimental data

C3 Conducted spectral analyses of experimental data

C4 Evaluated and suggested novel methods for leak detection and quantification

C5 Presented a holistic perspective on condition-based maintenance processes

C6 Outlined a specification for data gathering and analysis methods for the through leakage problem