Parts analysis, diagnostic tools avoid downtime

31st July 2020

Using structured control valve spares analysis and diagnostic tools enables a plant to identify its critical assets and plan for, rather than react to, valve maintenance needs. The result can be dramatic improvements in plant reliability and availability.

This tool was developed by life-cycle service care provider Unyazi, a division of power generation and mining engineering company Lesedi Nuclear Services.

A plant with an installed base of control valves has a limited budget and warehouse space for spare parts. It runs continuously as a 24-hour operation. Lesedi points out that if a valve fails and the parts are not readily available, the resulting downtime could cost millions.

Plant managers know that they need to improve monitoring and stock parts for critical valves. Lack of information about their installed valves poses a serious risk to plant availability. The plant’s maintenance team need to know the number and location of valves in critical applications.

Unyazi, an authorised Emerson Business Partner, can assist a plant’s maintenance team in life-cycle care and provide the advantage of asset-management tools as it uses Fisher FIELDVUE instrument diagnostics. Used in combination, these resources are key to improving the control of a valve’s reliability.

Unyazi’s evaluation focuses on valves in a plant. From the list of valves in those areas, Unyazi service personnel use recommended spare parts lists to identify different parts.

Valves are colour-coded (red, yellow, or green) based on two factors – availability and criticality. Red means the valves are essential to avoid safety issues or plant trips. Yellow designates important valves that could be down temporarily without sacrificing safety or load. Green refers to low-risk valves that could be repaired during the next outage, and it is eliminated from the list.

To further reduce the risk of downtime, the plant is standardised on FIELDVUE DVC6200-PD digital valve controllers for all critical valves.

With performance diagnostic capabilities, the instruments enable operators to run online tests of valve performance, identify problems before costly failures occur, and target valves in need of repair.

During a planned outage, operators can compare recent FIELDVUE scans of critical valves to the baseline performance curves they generated during the previous outage. By comparing the two reports, they can identify any degradation in control valves’ performance.

In using analysis tools, the plant orders 10% of the parts on the original recommended spares list. The order includes a mix of severe service (metal) trim parts, soft parts, new FIELDVUE DVC6200-PD instruments for control valves, and mounting brackets. By investing in on-site spares, plant managers can avoid downtime costs.

Beyond the monetary savings, the life-cycle services evaluation process enables the plant’s maintenance team to better manage their critical assets and facilitate next-day repairs as needed.