Respondent owned and operated a petroleum refinery and it’s RMP lists covered processes subject to Program 3 requirements, including the Ultracracker (ULC) unit which consists of three sixty-three-foot-tall pressure cylindrical reactors, each containing five individual catalyst beds. The hydrocracking reaction converts the larger hydrocarbon chains into smaller, more valuable hydrocarbons. On March 10, 2018, operators were returning the ULC to service after a turnaround that included maintenance (e.g. START-UP after maintenance) on the E-103 effluent exchanger. At 8:50 AM on March 10, 2018, a component of the E-103 effluent exchanger, the 127 J pump, tripped off. Operations personnel were able to restart the pump and return flow to normal rates, but the pump tripped off again at 9:10 AM and operations personnel were unable to return flow rate to normal. Operators decided to shut down the ULC process and depressured the unit to the flare at 9:59 AM. Operators identified a leak at the channel-to-cover plate flange on a component of the E-103 effluent exchanger, the I 03-CC2 exchanger.