Since 2007, the ASME B31.1 Power Piping Code has included mandatory requirements on the Operation and Maintenance (O&M) of Covered Piping Systems (CPS), previously called High-Energy Piping. The main concern is that the safety of these systems is very dependent on good O&M, which justifies its inclusion in the Construction Code. There is room for flexibility depending on individual circumstances but the responsibility is squarely laid on the Operating Company.
Requirements include that O&M procedures be available covering:
- Design limits of piping
- Recording of modes and hours of operation, of actual operating pressures and temperatures and of significant system excursions and transients
- Documentation requirements for modifications, repairs and replacements
- Documentation of maintenance on supports for piping that operates in the creep range
- Documentation of maintenance of piping system elements
- Assessment of degradation mechanisms which must include:
- "creep, fatigue, graphitization, corrosion, erosion, and flow accelerated corrosion"
- Water chemistry requirements
- Documentation of the Condition Assessment(s) - see below
- Any other required maintenance
The Operator is to decide the extent of the Condition Assessment depending on the piping system. For most Combined Cycle Power Plants with high temperature steam piping this would include an assessment of all of the degradation mechanisms mentioned above and would typically include:
- Design dimensions and operating conditions/life
- Actual dimensional checks and actual operating conditions and hours since the last assessment, including the number and types of starts (cold, warm, hot)
- Piping support hot and cold walk-down readings
- Modifications and repairs since the last assessment
- Any significant dynamic events
- An engineering assessment of high risk areas due to relevant damage mechanisms and a suitable NDT program to mitigate risks.
- Recommendations for future inspections
Further guidance is available in Chapter VII of the B31.1 code.
To manage these requirements, Tetra Engineering developed PipeVue 2.0 to store and organize inspection data in one easily-accessible solution, for both plant operators as well as engineers planning regular inspections. Using a 3-D model, PipeVue keeps track of the reported condition of different piping components in the steam cycle, helping plants to achieve a ASME B31.1-compliant Power Piping Management Programme.
Figure 1: Pipevue 2.0
 Frey, Joseph, High-Energy Piping Systems Are Now Covered Piping Systems, PVP2010-26069, Proceedings of the ASME 2010 Pressure Vessels and Piping Conference, 2010, Bellevue, USA.