We provided detailed engineering, design, and construction management for a grass-roots modularized process unit, featuring reactors, fractionation, pumps, exchangers, and more. Due to the unique high hazards present in the existing process unit, this grass-roots unit was specifically designed to be installed during a planned outage. Modules were constructed on-site in a laydown yard, and SPMTs (Self-Propelled Modular Transporters) were utilized to transport the modules to the process unit during the outage, ensuring a smooth and efficient installation process.