Heavy Lifting News
Case Studies on Innovative Problem Solving
HRSG Harp Replacement Is Music to Power Plant’s Ears
07/29/2025
Northeastern Power Station is a combined cycle power plant located in Oolagah, Oklahoma. In terms of electricity generation, the plant is ranked #6 out of 132 power plants in the OK state. The facility had a planned outage during which four harps inside of the Heat Recovery Steam Generator (HRSG) needed removal and replacement, (see image) The harps, named for their resemblance to the musical instrument, are parallel tube assemblies that are suspended in the gas turbine exhaust and serve as the primary surfaces for heat transfer to the water or steam within. Through a series of steps, the harp contents are superheated and directed to the steam turbine creating additional power (see image). Harps typically have a lifespan of 25-30 years.
CUST-O-FAB, a provider of specialty fabrication and onsite service for the power generation industry and located in Sand Springs, OK was contracted to remove the old harps and install the new ones. The existing harps, each weighing 30 tons, needed to be cut away and lowered five feet for removal and demolition, while the new harps needed to be lifted five feet into position. What sounded like a relatively simple operation was complicated by the low clearance above each harp and a congested work space. Faced with the logistical challenges, they reached out to Engineered Rigging for help identifying a bare rental solution.
After a good discussion with the CUST-O-FAB team our heavy lifting experts quickly identified a tried and true solution: Strand Jacks. Known for their compact footprint (9” l x 9” w x 48” h), eight Enerpac HSL 1507 Strand Jacks each with capacity of 17 tons were shipped to the power station along with a hydraulic power pack for each and control system consisting of two smartboxes and laptops. In addition to providing equipment rental, Engineered Rigging also designed and fabricated custom lift lugs to connect the harp to the Strand Jacks, trained CUST-O-FAB’s crew on how to install and operate the equipment, and provided on-site technical support.
When CUST-O-FAB told the ER team that the limited work space was a challenge, they weren’t kidding! A group of four Strand Jacks were positioned above the harp with just one foot spacing between the jacks. Once the 30 ton harp load was tranferred to the Strand Jack system, it was cut free from the HRSG, lowered five feet and set on a pre-staged trolley beam where it was rolled away for demo. The harp installation followed the same process, but in reverse. To maximize efficiency, the lift plan called for two harps to be removed at the same time. Once two of the new harps were replaced, the CUST-O-FAB crew repeated the process.
“During a planned power plant outage, timing is critical. With equipment rental, custom fabrication and technical support under one roof, Engineered Rigging was able to help our client complete the project on time, within budget and with peace of mind,” explained Mike Beres, Vice President of Engineered Rigging.
