Chevron | Pascagoula Refinery | Pascagoula, La.


OnQuest was retained by Chevron to upgrade two crude unit heaters at Pascagoula, including revamping or replacing several segments of the heaters.


OnQuest's planned improvements included engineering and design of radiant tubes, replacing the burners with next-generation ultra-low NOx burners, and redesigning and replacing the burner plenum and ducting. OnQuest was responsible for all design, procurement, fabrication and construction activities. Our work also included:

  • Replacing the convection section of one heater
  • Replacing the expansion joints and dampers common to both heaters
  • Replacing the radiant arch and arch tubes on one heater
  • Upgrading the floors and inspection doors, seal leaks, and tube hangers of the furnaces
  • Procurement and construction supervision


OnQuest's engineering solution for the reinstallation of the convection section entailed a complex and coordinated effort involving plant management, operations personnel, and construction crews. Given a 24-day turnaround window in which to complete the work, we designed the assembly of the tubes, transition ducting, and complete convection and breech sections to occur in a single lift.

Single-lift assembly is a difficult procedure but it can result in significant time savings when the turnaround window for a project is short. This method for on-site assembly has become a specialty of OnQuest, as the company increasingly works with dedicated on-site construction crews that are familiar with its designs, work process and quality requirements.

The combined weight of the revamped section to be replaced at Pascagoula was approximately 275 tons–resulting in our executing the largest single lift known to date of a completed convection section. Our work entailed cutting out and removing the material to be replaced and then swinging the new convection box into place for welding on site. Our completed work included the following features:

  • Used Computational Fluid-Dynamic (CFD) modeling and cold-flow modeling
  • Improved equipment reliability
  • Optimized product yields
  • Reduced NOx emissions