Outage Duration: March 1 – May 1, 2025
Dearborn Industrial Generation | Combined Cycle Facility
DIG HRSG Modernization Project
Mid-American Group (MAG) was engaged as the prime mechanical contractor to execute the comprehensive replacement of two Heat Recovery Steam Generators (HRSGs) at the Dearborn Industrial Generation (DIG) Combined Cycle Power Plant, a vital energy asset for the Midwest industrial and municipal grid.
Valued at $18.9M, the project was executed under an aggressive 60-day outage schedule, targeting significant improvements in thermal efficiency, reliability, and the operational lifespan of the facility.
HRSG Pressure Part Replacement
MAG executed the full-field replacement of sixteen total harp modules—eight modules per HRSG unit (2100 and 3100). Each harp was approximately 70 feet long, 10 feet wide, and weighed in excess of 106,000 lbs. MAG’s teams meticulously engineered precise lift and rigging plans, ensuring installation accuracy to sub-inch tolerances at elevations over 100 feet.
Demolition and Rigging
MAG conducted selective demolition involving top casing, access platforms, and structural steel to create critical harp access points. The demolition was carefully planned to preserve hanger rod hardware, facilitating efficient reinstallation.
MAG’s rigging engineers developed custom lifting frames, load control systems, and continuously adjusted lift plans in real-time to navigate obstructions and structural complexities onsite, demonstrating adaptability and precision.
Installation and Weld Compliance
Each harp module underwent precision placement, alignment, and securement, fully adhering to OEM specifications and ASME code standards. MAG’s in-house boilermakers executed over 464 welds, covering primarily 1″, 3″, and 6″ socket and butt weld configurations. Comprehensive weld mapping and daily tracking procedures ensured immediate quality control and compliance verification.
MAG’s QC team monitored weld fit-up accuracy, interpass temperatures, and adherence to WPS guidelines. Third-party nondestructive examinations (PAUT, PT, MT) validated 100% weld integrity, certifying absolute compliance with industry standards.
Cross-Discipline Integration
MAG provided substantial support across additional critical outage scopes:
1
Steam Turbine Generator (STG) and Gas Turbine (GT) assistance included rapid scaffold installations inside turbine compartments, facilitating OEM crews’ maintenance activities.
2
Assisted GE turbine specialists with complex rotor lifts, casing removals, and urgent mechanical support tasks via skilled MAG boilermakers and millwrights.
3
Provided certified riggers and boilermakers to third-party boiler contractors for upper penthouse tube replacements, maintaining stringent safety standards throughout collaborative work phases.
Scaffolding, Access, and Logistics
MAG oversaw the construction and inspection of over 100 OSHA-compliant scaffold structures, ensuring safe, reliable access throughout the boiler and turbine buildings. Equipment management and fueling operations were rigorously maintained around-the-clock, alongside dedicated housekeeping and Foreign Material Exclusion (FME) enforcement teams, promoting a clean, efficient working environment.
Innovation and Problem Solving
MAG’s onsite engineering team adeptly managed unforeseen challenges, rapidly modifying rigging plans overnight to prevent costly downtime. They engineered custom pipe cradles to protect high-value pressure parts during handling and designed specialized skids and frames for efficient harp module storage and movement, significantly streamlining operations.
MAG’s integrated team structure—boilermakers, millwrights, riggers, scaffolders, carpenters—enabled seamless coordination and faster workflow. Eliminating traditional trade handoffs ensured faster weld turnover and reinforced project accountability.
Safety and Quality Excellence
MAG achieved a zero-incident safety record (0.00 TRIR) through comprehensive safety oversight, daily hazard assessments, and diligent enforcement of safety protocols. Quality assurance was meticulous, with weld documentation, scaffold certifications, and NDE reports compiled into detailed turnover packages delivered promptly at project completion.
Outcomes and Impact
MAG successfully completed the full system turnover on schedule, allowing DIG to resume commercial operations precisely as planned. The HRSG replacements provided a measurable
~1.8% improvement in thermal efficiency and significantly extended equipment life expectancy by an additional 25 years.
MAG’s proactive field presence, combined with unmatched craft expertise and innovative problem-solving capabilities, established the benchmark for future projects of similar scope and complexity. The project’s execution solidified DIG’s reputation for operational excellence within the industry.
Conclusion
From initial mobilization to final system turnover, MAG fully owned and executed the DIG HRSG modernization outage. MAG’s multi-disciplinary capabilities, rigorous quality standards, and adaptive engineering expertise delivered exceptional results under a demanding schedule.
MAG’s involvement in this outage reinforced their reputation as a leading, fully self-performing, ASME-certified contractor in the industrial power generation sector, well-equipped to execute complex projects efficiently and reliably.