Ensuring Safety, Reliability, and Efficiency
Covered Piping Systems (CPS) are a critical element in assuring safe and reliable operations of power plant piping in steam power plants and other systems designed to the ASME Code for Pressure Piping, B31. CPS was defined in late 2008 by ASME as the number of independently owned power plants (as compared with similar plants owned by regulated utilities) was rapidly increasing.
Unlike other components such as boilers/HRSGs, steam turbines, or gas turbines, piping is distributed over a large area, comprised of many subcomponents, installed and welded on-site, with a design generally customized for each plant. Depending on its function, piping is susceptible to various damage mechanisms, including:
- High-Temperature Steam Piping: Creep, fatigue, degraded P91/P92, weld defects.
- Attemperator Piping: Quench cracking, dissimilar metal welds.
- Feedwater and Attemperator Piping: Flow-accelerated corrosion (FAC) and erosive wear (EW).
- High Temperature Steam Drain Cracking: Fatigue cracking and wear, valve nozzle cracks, hanger damage & failures.
- Corrosion Under Insulation (CUI); predominantly affects small bore (drain systems) but also large bore exposed to marine environments.
Performing periodic inspections (visual & NDE) is crucial for prolonging the safety, reliability, efficiency, and profitability of power piping systems. A key objective is the targeted and judicious use of inspection resources to detect damage in plant piping systems. Although the focus is on large-bore piping, the overall condition of the piping including smaller bore lines should also be verified.
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