Combined Cycle Power Plant Maintenance Guide: HRSG, Steam Turbine & BOP

For baseload CCGT plants (above 7,000 equivalent operating hours per year), HRSG pressure-part inspection intervals are primarily run-hour driven — annual outages align with OEM recommended inspection cycles. For cycling plants (below 5,000 EOH/year with frequent cold starts), inspection intervals must be supplemented by start-cycle counting. A plant that executes 150 cold starts per year accumulates fatigue damage equivalent to thousands of additional operating hours in high-stress components like attemperators and HP headers. OxMaint tracks both run hours and start cycles for each asset and generates inspection triggers based on whichever threshold is reached first — not just calendar intervals. Book a demo to see multi-trigger PM scheduling in action.

Generator step-up transformer dissolved gas analysis follow-up. DGA samples are typically taken on schedule — but when results show elevated fault gases, the follow-up work order (repeat sample within 30 days, mobilize transformer specialist) frequently gets deferred or lost in manual tracking systems. The consequence is a transformer failure that averages 90+ days to repair and $2M+ in combined repair and lost generation cost. OxMaint automatically creates a mandatory follow-up work order when DGA data is entered and fault gases exceed threshold — the follow-up cannot be closed without a qualified approval, preventing the deferral that causes most transformer failures.

This is the core multi-asset tracking challenge in CCGT operations. In OxMaint, the gas turbine and HRSG are configured as parent-child assets in the same hierarchy, with shared operational parameters (exhaust temperature, exhaust flow, GT firing temperature) linked to both asset records. When a GT inspection finds above-normal hot-section degradation — indicating elevated exhaust temperature exposure — OxMaint's linked asset logic automatically escalates the HRSG HP superheater inspection from its standard annual interval to the current outage scope. This prevents the scenario where GT operating condition changes go unnoticed in the HRSG maintenance program.

A full CCGT planned outage (GT hot-gas-path, HRSG, steam turbine, and BOP) typically generates between 200 and 450 work orders in OxMaint, depending on plant complexity and scope additions from previous inspections. Of these, approximately 60–70 are critical-path work orders with milestone dependencies. OxMaint's outage planning module handles this scale natively — work orders are grouped by system, work center, and crew assignment, with the critical path dashboard showing real-time completion status against the planned outage window. Plant managers report that outage visibility improves significantly when the entire scope is managed in a single system rather than split between a CMMS and a separate project schedule.

CCGT outage compliance documentation requirements include: LOTO and isolation certificate records for every work order (OSHA 29 CFR 1910.147), pressure vessel inspection reports for HRSG and steam turbine casings (National Board inspection certificates), electrical safety permit records for all HV work (NFPA 70E compliant), corrective action tracking for all inspection findings with closure sign-offs (NERC MAN standards for bulk electric system generators), and as-found and as-left condition records for all rotating equipment. OxMaint generates all of these as audit-ready exports — timestamped, attributed, and traceable from work order to completion. Start a free trial to see the compliance reporting module.

Yes. OxMaint supports equivalent operating hour calculations that weight run hours, cold starts, warm starts, hot starts, and trip events against configurable multipliers based on OEM guidance or plant-specific experience. The asset record for each steam turbine stage accumulates EOH continuously, and PM schedules are triggered against the EOH counter rather than calendar intervals or raw run hours. For a cycling CCGT unit running 200 cold starts per year at a typical EOH multiplier of 10x, the HP turbine internal inspection may trigger at 36 months wall-clock time despite the unit only accumulating 6,000 run hours — exactly as required by the thermal fatigue loading it has experienced.