Bancroft Contracting Corporation replaced the economizer inlet header on NextEra Energy’s Unit 4 power boiler, at the Wyman Station power plant on Cousin’s Island in Yarmouth, Maine.
The project required removal and replacement of the existing 19.5-inch diameter, 3-inch thick, 75-foot long, carbon steel header from the 112-foot elevation within the plant, and installation of 411dutchmen. The project was completed on budget, one week in advance of the allotted four-week schedule.
The project required novel solutions to a variety of rigging and welding challenges. These included removing and replacing the 20-ton header through a penetration in the boiler house wall nearly 12 stories above ground, as well as completing 822 tube welds and three circumferential welds of the header.
Project Manager for Next EraEnergy was Justin Zandan, Bancroft Contracting Corporation was general contractor, represented on site by Ben Thone, Project Manager and Superintendent, and Tim Wilcox, Quality Control Manager.
Contribution to the Community
The economizer header is an integral and critical component of the Number 4 power boiler at the Cousin’s Island plant. The existing economizer header measured 2.6” in average wall thickness upon removal and evidenced ligament cracking due to cycling fatigue at the critical junctures between tube penetrations.
NextEra’s Wyman Station plant is a peak generation power plant. The function of the plant is to augment regional electric supply during periods of peak electric demand. Next Era’s investment in the economizer header upgrade and Bancroft’s execution of the project, helps assure reliable, efficient electric supply for Maine and the New England region for decades to come.
Job Challenges & Innovation
This challenging project required Bancroft Contracting to begin and complete the work within strict time constraints imposed by NextEra and regional regulators. A Bancroft crew of approximately 15 welders, fitters and skilled mechanical hands, worked around the clock on 12-hour shifts to complete the project a week ahead of the allotted four-week schedule.
Removing and replacing the 20-ton, 75-foot long header from the plant was the first significant challenge of the job. This task required the design and installation of an overhead monorail system to deliver the header components to the boiler proper, as well as construction of a trolley system spanning the width of the boiler’s heat-recovery area. All movement and positioning of the massive header components had to be completed without the use of heavy equipment once the components were inside the boiler house.
The project also required hundreds of fits and welds all of which were completed on a demanding schedule with zero re-work. Welding out of the new header alone required buddy-welding techniques utilizing up to three two-man teams welding in 12-hour shifts, daily for a total of four days, while executing X-ray testing requirements on opposite night shifts. Despite the challenging schedule and the massive quantity of welding completed on the header joints, every X-ray test was passed successfully and no re-work was ever required on even a single joint.
The Economizer Header project was carried to completion without adverse environmental impact. The tons of scrap steel the project generated were recycled. The project waste stream was contained and appropriately disposed. Impacts to water and air were minimal or non-existent.
The project has positive environmental impact in that it will permit this important New England power boiler to run and produce clean electric energy at peak efficiency.
Response to Client Needs
Bancroft Contracting planned and executed the Economizer Header Project with consistent attention to the power production requirements of NextEra Energy. In order to minimize down time for the Unit 4 Power Boiler the work was carefully pre-planned and extensive pre-outage preparation took place while the boiler remained available for use.
Once the Unit 4 Power Boiler was taken out of service for the project, Bancroft committed crews around the clock, advancing the project as rapidly and efficiently as possible, consistent with the demands of safety and quality.
Bancroft’s completion of this challenging project a week ahead of the original four-week outage schedule was due to several factors:
- Excellent cooperative pre-outage planning by NextEra and Bancroft
- The great morale and unflagging efforts of the Bancroft crew
- Thoughtful and effective project management by superintendent Ben Thone
- Exemplary cooperation, communication and project support from NextEra
Relying on workplace safety practices and the “zero accidents” culture developed and practiced over years at both NextEra and Bancroft Contracting allowed Bancroft crews to complete this high-risk, time-critical project with zero incidents and zero injuries. The Economizer Header project began and ended with no daylight between owner and contractor with respect to the priority placed on worker safety.
Credit for this accomplishment belongs in several places: NextEra has always made it clear that production never takes precedence over safety on their projects. Project Manager Ben Thone and Bancroft Safety Specialist Don Partridge provided effective safety leadership for the duration of the project. However, the lion’s share of the credit for this outstanding safety accomplishment goes to the Bancroft crew. These trained and seasoned construction professionals worked under the most demanding conditions possible without compromise to safe work practices, producing safety results for the Economizer Header project second to none in the industry.