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Marathon Ashland Petroleum (3165), Garyville

Releases of NOx

LDEQ Accident Number
Accident Date
Point Source(s) Notes Amount of Release

FCCU wet gas compressor first stage
Cause: A loose wire in a satellite building caused the Fluid Catalytic Cracking Unit (FCCU) wet gas compressor first stage spillback to open, which led to high fractionator pressure. The safety instrumented system (SIS) tripped the FCC unit on high fractionator pressure. During the FCC unit startup, the debutanizer pressured up and had to be vented to flare due to lack of heat in the upstream stripper reboiler (heating medium is BPA from the fractionator) which sent ethane to the debutanizer. The flaring event due to the FCCU Shutdown began on June 7, 2014 at 14:37 hours and stopped on June 7, 2014 at 15.48 hours for a duration of 70 minutes. The flare event due to the FCCU startup began on June 7, 2014 at 18:21 hours and stopped on June 7, 2014 at 20:18 hours for a duration of 117 minutes. The total duration of the flaring was 187 minutes.

Followup: No

Notes: The SIS system reacted as designed to shutdown the FCCU due to the opening of the compressor spillback valve. During FCCU startup the operating procedure was followed to minimize emissions to the extent possible. An incident investigation will result in recommendation items designed to prevent the recurrence of this event.
22.1 pounds

Tank 5000-6
U215 hydrocracker
Cause: An emergency shutdown device was triggered due to an incorrect reading on the Treating Reactor Bed 3 temperature indicator in the U215 hydrocracker which depressurized the unit to the South Ground Flare. In response to the shutdown, operations utilized the refinery slop line to deinventory the unit, routing material to Tank 500-6. Natural gas was inadvertently routed through the refinery slop line where Tank 500-6 received the vapor, causing a release through the tank seals. Human factors also played a role in the incident.

Followup: Yes

Notes: Root causes identified as Equipment Difficulty-Design Specs and Procedures Followed Incorrectly. At the time of the release, the emergency shutdown system was activated as designed shutdown the hydrocracker. Multiple recommendations have been identified to prevent a recurrence. The Tech Services Department at MPC has been tasked with mitigating the hazards of a single point of failure due to false temperature indication (anticipated completion 1/31/15). The operations department will develop and implement a system to verify all steps are completed and signed off when following procedures. A team will be developed to conduct a hazard analysis on the entire refinery slop system to implement necessary safeguards to prevent unwanted material from entering the slop system.
108.3 pounds


Railcar Inlet Valve
Cause: After loading a propylene railcar, the operator noticed that the inlet valve was leaking and could not be closed. The railcar was depressured to the flare so it could be disconnected and the valve repaired.

Followup: No

Notes: None. The contents of the railcar were vented to the North Flare Stack. The railcar was sent for repairs.
11.4 pounds