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Shell Chemical East (26336), Norco

Causal Factor: Instrument Failure

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

Motiva West Operations Ground Flare (EPN 9-84); GO-1 Elevated Flare (EPN 1-90)

Cause: On June 22, 2012 Shell Chemical's GO-1 flared at the GO-1 Elevated Flare. The flaring was a result of a malfunction in the computer control system. On June 22, 2012 Shell Chemical's GO-1 experienced a unit upset which led to flaring at Motiva's West Operations Elevated Flare (EPN 9-84). The flaring was a result of a malfunction in the computer control system.

Followup: No

Notes: GO-1 operations took the necessary steps to safely return the unit to normal operating conditions and the flaring stopped. The follow-up later was sent more than 7 days after the incident occurred. Maintenance worked with the manufacturer of the DCS and discovered there was an issue with a card in the system. Upon filing the cards memory, a dumping of memory and resetting of the card occurs. This process led to the unexpected shutdown of equipment and the upset in the GO-1. The manufacturer had identified the problem with these cards, but no action to correct the issue had occurred. Maintenance has replaced the card with the issue in order to prevent a reoccurrence of this incident. Motiva did not exceed any reportable quantities or maximum permitted limits during this event. Shell Chemical East did not exceed any reportable quantities, but they did exceed their maximum permitted limits for carbon monoxide, nitrogen oxides, particulate matter, and volatile organic compounds. The pollutant totals were determined by adding together the releases from both Shell Chemical LP - East, GO-1 Elevated Flare (EPN 1-90) and Motiva West Ops Elevated Flare (EPN 9-84) together.

Toluene: 0.2 pounds
Hexane: 4.4 pounds
Benzene: 2.9 pounds
1,3-Butadiene: 14.2 pounds
Volatile Organic Compounds (VOCs): 5,893.9 pounds
Sulfur Dioxide: 43.2 pounds
Particulate Matter: 352.9 pounds
Nitrogen Oxide: 1,874.7 pounds
Carbon Monoxide: 10,200.8 pounds


OL-5 Elevated Flare FE-101 (EPN 6-84); OL-5 Ground Flare FG-101 (EPN 7-84)
Cause: On March 12, 2012 Shell Chemical's OL-5 Unit Operators got an indication that the Process Gas Compressor (PGC) first stage control valve had opened to the flare system due to high suction pressure. The PGC turbine had slowed down causing the kickback valves to open. Slowdown of the turbine was caused by a high level in the surface condenser. The materials were released from OL-5 Elevated Flare FE-101 (EPN 6-84) and OL-5 Ground Flare FG-101 (EPN 7-84).

Followup: No

Notes: OL-5 Operations lowered the surface condenser level and the kickback flows to lower the first stage suction pressure. These actions stopped the flaring. All materials routed to flare were combusted with an approximate destruction efficiency of 99.5% released from the OL-5 Elevated Flare and Ol-5 Ground Flare to the atmosphere and dispersed naturally. Maintenance was called in to troubleshoot the surface condenser level indication. Instrument mechanics checked level controller and found dirt on the flapper nozzle. The nozzle was cleaned and proper operation of the control valve was checked. Instrument mechanics also found the door to the instrument center in the open position, which possibly allowed dirt into the enclosure. Operational rounds have been updated to include the task to check enclosure doors. Propylene is listed in the LDEQ's Verbal report as having been released as well, but there is no mention of it later on in the follow-up report from Shell. The measurements were obtained by adding the same pollutants from both flares together. Initial report states material did go offsite. Air was monitored around the perimeter of the facility. No reportable quantities were exceeded, but permit levels were exceeded for ethylbenzene, toluene, and xylene.
Carbon Monoxide: 523.5 pounds
Nitrogen Oxide: 96.2 pounds
Particulate Matter: 18.1 pounds
Volatile Organic Compounds (VOCs): 249.6 pounds
Butadiene: 16.1 pounds
Benzene: 13.0 pounds
Ethylbenzene: 1.2 pounds
Toluene: 9.1 pounds
Xylene: 4.7 pounds

OL-5 Elevated Flare (EPN 6-84) & Ground Flare (7-84)
OL-5 Elevated Flare (EPN 6-84) & Ground Flare (7-84
Cause: On November 28, 2013, OL-5 operations experienced a false high flow reading on a flow controller that resulted in high pressure in the diethanolamine stripper overhead. The high pressure caused a backup pressure controller to open the OL-5 Elevated Flare and OL-5 Ground Flare.

Followup: Yes

Notes: Upon investigation, it was discovered that the false high flow was the result of the plugging of one of the two transmitter taps. OL-5 operations and maintenance personnel cleared a plug from the transmitter taps of the flow controller, and the flow reading returned to normal operating conditions. The OL-5 Process Unit was safely returned to normal operation conditions, and the flaring stopped. Follow up report states that "additional measures to prevent reoccurrence have not been identified".
Sulfur Dioxide: 6.7 pounds
Carbon Monoxide: 1.6 pounds
Nitric Oxide: 0.3 pounds
Particulate Matter: 0.5 pounds
Volatile Organic Compounds (VOCs): 0.1 pounds

OL5 Ground Flare (EPN 7-84) and OL5 Elevated Flare (EPN 6-84)
Cause: Shell Chemical's OL5 Unit flared carbon monoxide, nitrogen oxide, propylene and volatile organic compounds at the OL5 Ground Flare (EPN 7-84) and OL5 Elevated Flare (EPN 6-84). The flaring was a result of the propylene analyzer showing that propylene was off specification. After discovery, instrument technicians evaluated the analyzer and a sample of propylene was sent to the lab to verify the analyzer.

Followup: No

Notes: Motiva's industrial hygienists are monitoring downwind of the flare. Data gathering to perform calculations and investigation are ongoing.


GO1 Unit
Cause: The GO1 Unit flared process gas as the result of an instrument giving a faulty signal.

Followup: No

Notes: The investigation is ongoing and the report states that Shell plans to provide a follow-up.