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Mockup Proves Essential in Award-winning Job

Barnhart recently was recognized with the Specialized Carriers and Rigging Association (SC&RA) Rigging Job of the Year $750,000 to $2 million. It was one of two award-winning projects that included the SC&RA Rigging Job of the Year under $150,000.   

The client, a nuclear power plant in Georgia, needed to remove and replace their Alpha and Bravo 8th Stage Feedwater Heaters (FWH) located in the basement of the turbine generator building. This critical path project would take place during a scheduled 30-day refueling outage.

The two heaters were located side by side one beneath the other on the 112-foot elevation floor level that was congested with columns, piping conduit and drains. The heaters would have to be jacked up and transported to a hatch opening and lifted approximately 50 feet to the turbine deck. They would then travel to the truck bay hatch for removal.   

Floor conditions and travel path obstructions were a challenge. There was no straight or clear path to the hatch opening, which was not large enough to allow the FWHs to be lifted through the hatch in a horizontal position. The heaters would have to be tipped, but the angle could not exceed 69 degrees due to OEM warranty restrictions.

Headroom in the hatch opening and the rigging angles it created meant that the standard rigging practice of tipping with chain hoists wasn’t feasible.  The use of a specialty lifting device would be needed.   

Putting the Tipstick to the Test

Due to the complexity of the project, the client asked Barnhart to first provide an engineering feasibility study and rigging plan. The specialty lifting device the team proposed was a custom designed 150-ton Tipstick with a moveable lifting point. The client had concerns about using the Tipstick and requested a mockup of the critical lift through the hatch opening for validation.

The mockup at the Port of Memphis.

The mockup was performed at the Port of Memphis utilizing a 1,250-ton Derrick crane. A concrete-filled vessel with additional counterweight served for a functional/load test of the Tipstick to 125% of the load weight. A 70’ scaffolding structure was erected to replicate the hatch opening.  Barnhart used an actual replacement feedwater heater that was stored in a nearby warehouse for the mockup lift to validate the plan. 

Once the removal method was confirmed, the crew got started at the site. The team used 50-ton jacks to raise each heater to install a 100-ton Lite Slide Track System. The heaters were skidded about four feet and jacked up to transition from the slide track to the powered saddle rollers equipped with a custom bolster plate.  The steerable hydraulic roller system allowed the front of the heaters to maneuver around interfering columns. This process was repeated to transition the tailing end of the heaters to maneuver their way to the equipment hatch.

Successful removal at the site.

The heaters were then lifted through the floor opening of the equipment hatch to the Turbine Deck. Inclinometers were monitored closely to confirm that the rigging plans were followed and that the tipping angles would not void the warranties required by the OEM.

Once leveled back to a horizontal position, the overhead crane transported each heater to the truck bay opening and lowered them to a Goldhofer trailer. The larger replacement heaters were installed in reverse order.    

As for the total impact on critical path, the customer scheduled 30 shifts to complete Barnhart’s scope of work. The project was finished in about 24 and a half shifts, 65 hours ahead of schedule.