Fines pits are vital to the operations of every coker unit in a refinery. The fines pit typically has a series of walls or "meanders" that process water goes through in an attempt to remove suspended coke particles prior to the water being sent for processing. When the process water entered the meanders, the solid particles in the water would drop out so that only the water needing to be processed remains. Therefore, the bottom of the fines pit would get filled with the coke from the process water and need to be regularly cleaned. Refineries clean out the bottom of the pit with a large crane bucket.  During cleaning, the top of the concrete meander walls would get hit with the gantry crane bucket (on accident), which damaged the structure. Structural Preservation Systems (SPS) is the industry leader in repairing coker units and had worked on this coke pit (which is adjacent to the fines pit) at the refinery approximately four years earlier. The owner had such a positive experience working with SPS that they contracted them to perform the repairs to the coker fines pit meanders.

SPS' visual inspection of the fines pit meander walls revealed that every wall had some level of impact damage at the top from the gantry crane. Upon further review, SPS determined that the walls were structurally sound and only the damaged sections on the top would need to be repaired. SPS developed an innovative repair strategy to provide a long-term solution for the owner. Typically, contractors repair the meander walls back to original design, but SPS has developed a new top section that will drastically reduce the wear and tear on the concrete walls from impact loads.  SPS' solution involved incorporating a curved glancing plate made of steel that would handle the hits from the gantry crane. To begin the work, the top 1-foot of eight walls (for a total of 400 linear feet) was removed. After the damaged concrete was removed, SPS augmented or replaced damaged reinforcing bars and abrasive blasted the exposed concrete substrate to ensure a well bonded repair. Crews installed a mortar tight formwork to the top of the meanders that incorporated the glancing plate. The glancing plate was engineered with nelson studs that were embedded within the new repair material. Once the rapid curing, high strength repair material had cured, crews installed a water-based curing compound to help mitigate dry-shrinkage cracking.

Construction of the formwork was a major challenge on this project. The formwork had to be engineered and designed to hold not only the weight of the concrete repair material, but also the heavy steel glancing plate. Cranes were used to lift and set the glancing plate pieces into place. As with most turnaround projects, there was close coordination with other contractors to ensure tight schedules could be met.

Work had to be performed during a turnaround from mid-January 2009 to mid-February 2009. Crews worked around the clock to complete the project within the tight timeframe. SPS was able to finish the project ahead of schedule and the owner was extremely pleased with the result.