PCS Nitrogen Ltd. (a wholly owned subsidiary of Potash Corp.), operates four ammonia plants at the Point Lisas, Trinidad, facility. The smallest unit, the No. 3 ammonia plant with a nameplate capacity of 750 stpd was built in 1965 for Collier Carbon & Chemicals, Brea, California. In 1994, the plant was relocated to Point Lisas, Trinidad. Over time, the plant capacity was increased to 830 stpd through minor modifications mostly to the back of the ammonia synthesis loop. Previous expansion studies showed that further rate increases were economical due to favorable natural gas (NG) costs in Trinidad. Likewise, new developments in ammonia converter technology would improve operating costs of this older unit. However, these studies also identified the primary reformer as a major bottleneck. This case history explores the planning and design stages used to revamp the primary reformer of the No. 3 ammonia unit.