Originally constructed in 1968, the sponge coker unit was upgraded in the spring of 2012
Removing deteriorated concrete in a support column
Placement of concrete in new reinforced coke pit slab.
Placement of concrete in new reinforced coke pit slab. Walls with portions of concrete removed.
Suspended deck system was used to access the head deck areas, while below it, swing stages with angular stirrup brackets were used on the coke chutes.
Concrete placement in head deck slab with limited access space.
Placement of high strength dry shotcrete to offer high early and ultimate strengths, as well as impact resistance to the coke pit walls.
One of several collection boxes for Safety Observation Reports on the jobsite. The reports were used by crews to correct unsafe acts or conditions – and were critical safety element that resulted in an incident-free project.
United States
Project Team 
Specialty Contractor
Engineering Subcontractor
Material Supplier

CITGO Lemont Refinery

Project Highlights 
  • Schedule: The comprehensive ultra fast-track project required to be completed during shutdown was completed on time.
  • Safety: The stringent safety requirements of the client were exceeded through STRUCTURAL’s pre-planning and focus on safety throughout the project.
  • Quality & Performance: The sponge coker unit at CITGO’s Lemont Refinery will continue to operate safely with the concrete repair and strengthening program implemented during the turnaround. The repair allows the refinery to install upgraded equipment and extend the service life of this critical system and process
Project Description 

A large petroleum refinery in the United States, driven by a commitment to safe and efficient operations, planned structural repairs to its coking unit during a scheduled 30-day turnaround. Originally constructed in the 1960’s, the coker structure repairs would allow for continued safe operations, and the future installation of new new coke drums

To complete the repairs, the owner required a specialty contractor that could bring together the necessary project management, manpower, equipment, and materials expertise to safely execute the large scope of work in a short duration turnaround. STRUCTURAL, a Structural Group company, was selected as the specialty contractor to integrate with the owner’s project team based on its safety record, past performance, experience working on coker units, as well as its ability to provide investigation and design through STRUCTURAL TECHNOLOGIES, another Structural Group company.

Scope of Work

A full investigation of the coking unit revealed that the supporting concrete elements required repairs to several areas, including the head deck, its supporting columns and beams, coke chutes, as well as the coke pit walls and floors.

The primary purpose of this project was to restore and improve the functionality of the coking unit. The unit’s civil infrastructure is exposed to high temperatures, chemicals, and repeated impact from equipment to handle the coke product – meaning that material selection was a key component to meet durability requirements. 

The project team drew upon the experience of the contractor to develop a suspended deck system to provide work access to the head deck beams and slabs, while a custom angular stirrup system was used to provide access to perform repairs on the coke chutes. The access systems met stringent protection requirements for crews simultaneously working in the chutes and pit areas below.

Build – Project Execution

For the concrete repair work items, over 200 concrete repair specialists assembled on the job – dividing into two crews that worked 12 hour shifts for 30 straight days.

On the head decks of the coking unit, over 900 square feet of the support columns and beams were repaired and strengthened, using approximately 30 yards of concrete. Four of the six head decks were completely removed and replaced with approximately 120 yards of concrete over 2,000 square feet. Full depth concrete repairs were also completed on the angled coke chutes for all six drums.

The coke pit area was repaired, first by pouring a leveling mud slab with over 200 yards of concrete, then an under drain system was installed, topped by a new reinforced concrete slab that utilized over 300 yards of concrete. A transition slab was built to join the new slab to the existing coke pit ramp. Additionally, concrete repairs were completed on the north coke pit wall.