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Shell Chemical East (26336), Norco

Causal Factor: Equipment Failure

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

GO-1 Elevated Flare (EPN 1-90)
GO-1 Elevated Flare (EPN 1-90); Motiva West Operations Ground Flare (EPN 9-84)
Cause: On August 18, 2012 Shell Chemical's GO-1 flared at the GO-1 Elevated Flare. The flaring was a result of an unexpected shutdown of the dry gas compressor. On August 18, 2012 Shell Chemical's GO-1 experienced a unit upset which led to flaring at Motiva's West Operations Ground Flare (EPN 9-84).

Followup: Yes

Notes: GO-1 operations took the necessary steps to minimize flaring and safely return the unit to normal operating conditions and the flaring stopped. Troubleshooting of the compressor was done to determine if the compressor could be safely restarted. The compressor was returned to normal operating conditions. A determination of why the compressor shutdown was inconclusive. Repairs were made to the compressor by Shell Chemical to allow for the compressor to be restarted and flaring stopped. Due to flaring at the GO-1 Elevated Flare (EPN 1-90), Shell Chemical East exceeded its reportable quantity for sulfur dioxide and its maximum permitted limits for carbon monoxide, nitrogen oxide, particulate matter (reported as smoking), sulfur dioxide, and hexane. The GO-1 Elevated Flare (EPN 1-90) flared for 0 minutes. Due to flaring at the Motiva's West Operations Ground Flare (EPN 9-84), Motiva exceeded the maximum permitted limit for hexane. They did not exceeded any reportable quantities. They also released carbon monoxide, nitrogen oxide, particulate matter (reported as smoking), sulfur dioxide, and volatile organic compounds.
Sulfur Dioxide: 1,343.2 pounds
Carbon Monoxide: 1,365.9 pounds
Nitrogen Oxide: 251.0 pounds
Particulate Matter: 47.3 pounds
Volatile Organic Compounds (VOCs): 372.4 pounds
Hexane: 34.6 pounds

Utility Boiler #10
Cause: A resident of the Norco community called and reported to the Shell East Site Supervisor that smoke was sighted in the air above the refinery and inquired as to the seriousness of the issue. Shell was aware of the upset of Utility Boiler #10. Operations personnel were in the process of shutting down the pyrolysis pitch system due to a failed transmitter.

Followup: No

Notes: Upset of Utility Boiler #10 and black smoke sighting was called and reported to Shell East Site and Shell East Site Supervisor. Shell attempted to put this incident in Shell Chemical LP-Norco Chemical Plant-West site. Smoke caused by their process of putting pyro pitch in boiler. For unknown reason it started the black smoke. When pitch was removed, smoke ceased. There were no materials released from the incident above a reportable quantity and no permit limits were exceeded.The initial report states the material did go offsite.


pressure relief valve
Cause: On December 24th 2013, Shell Chemical's OL5 operations discovered a pressure relief valve opening to the OL5 flare system.

Followup: Yes

Notes: OL-5 operations began working to remove non condensables in an attempt to get the relief valve to close. To close the pressure relief valve and stop the flow to the flare system, operations reduced the pressure upstream of the pressure relief valve, returning the unit to safe, normal operating conditions.


level control valve in the de-methanizer system
level control valve
Cause: On November 24, 2013, Shell Chemical's OL-5 operations discovered a packing leak on a level control valve in the de-methanizer system of the OL-5 Process Unit.

Followup: No

Notes: Operations took immediate action to mitigate the leak and have repairs made to the valve.


OL5 Elevated Flare (EPN 6-84) and Ground Flare (EPN 7-84)
Cause: On the night of September 8, 2013, Shell Chemical's OL-5 Unit experienced plugging of their online recycle filter located on the bottom of the pyrolysis fractionator (pyrofrac). Once plugged, the level at the bottom of the pyrofrac increased resulting in the level of the quench drum to decrease. This resulted in diversion of feed from several furnaces at OL-5. While stabilizing the OL-5 process unit, operations personnel experienced an upset in the process streams that resulted in flaring at the OL-5 Elevated Flare and OL-5 ground flare.

Followup: Yes

Notes: To minimize impacts, OL-5 operations made various process adjustments, while taking the furnaces off line. These adjustments stabilized the unit and reduced, eventually eliminating, the flaring. These adjustments also prevented the unit from shutting down. To prevent future occurrences, additional filters will be installed to create a robust filtering system. Report states that all released materials were dispersed naturally in the atmosphere from the OL5 Ground and OL5 Elevated flare stacks. Initial report stated that no reportable quantities were exceeded. Following the investigation and calculations, Shell Chemical confirmed they exceeded the reportable quantity for highly reactive volatile organic compounds.
Carbon Monoxide: 8,094.0 pounds
NOx: 1,487.6 pounds
Volatile Organic Compounds (VOCs): 3,775.1 pounds
Particulate Matter: 590.7 pounds
Highly Reactive Volatile Organic Compounds (HRVOCs): 664.0 pounds


Cause: On July 29, 2013, there was a release of 1,3 butadiene, benzene, and hydrogen sulfide due to a GO-1 process gas leak to the condensate system. While working with operations, personnel monitoring the fugitive emission components in the unit found the GO-1 caustic column feed pre-heater exchanger leaking process gas to the condensate system. Operations redirected the contaminated condensate to the flare system due to the condensate system flash drum venting to the atmosphere.

Followup: Yes

Notes: GO-1 operations took the necessary steps to minimize the release to the atmosphere. Operations personnel were able to complete a management of change to route the contaminated condensate to the flare. The leaking exchanger is scheduled for a metallurgy upgrade during the next GO-1 North turnaround. Upgrading the metallurgy should prevent any future leaks.
Highly Reactive Volatile Organic Compounds: 249.6 pounds


BD5 Unit post fractionator
Cause: On 5/9/2014, Shell Chemical's BD5 Unit flared process gas at the OL5 Ground Flare (FG-101). The pressure of the post fractionator unexpectedly increased resulting in a unit upset requiring BD5 to flare 1,3 butadiene product to safely stabilize the unit. It was determined that the pressure increase on the post was the result of a malfunctioned pressure transmitter.

Followup: Yes

Notes: Immediately, to minimize additional unit upset conditions and impacts, various process parameters were monitored and it was determined that the pressure increase on the post was the result of a malfunctioned pressure transmitter. The transmitter was monitored until repairs could be completed. To prevent the reoccurrence of this incident, maintenance evaluated the pressure transmitter and found that there was moisture inside the wiring terminal portion of the transmitter and the transmitter had loose wiring. The moisture was removed, wiring was tightened and it was verified that the transmitter cover was sealed to prevent reentry of moisture.
Carbon Monoxide: 72.0 pounds
Nitrogen Oxide: 13.0 pounds
Particulate Matter: 2.0 pounds
Volatile Organic Compounds (VOCs): 48.0 pounds
1,3-Butadiene: 48.0 pounds

OL5 Unit RV
Cause: On 4/15/14, Shell Chemical's OL5 Unit flared process gas at the OL5 Ground Flare due to a relief valve (RV) on the ethylene product heater unexpectedly lifting. The pressure transmitters and gauges throughout the ethylene product system did not indicate any abnormal unit operation. It was determined that the relief valve malfunctioned by lifting prematurely.

Followup: Yes

Notes: To minimize additional unit upsets and impacts, operations personnel verified the readings from the pressure transmitters and gauges throughout the ethylene product system. Operations personnel safely removed the malfunctioning RV from services and subsequently replaced it. The malfunctioning RV was replaced on 4/22/14. Note that some reporting inconsistencies should lead to questions about the actual amounts released. For example, the refinery report suggests that total VOCs and HRVOCs are the same in the reporting documents. Further, some calculation errors seem apparent, as seen in the last row of table V.5; researcher asserts that the value in the last cell should be 0.23 rather than 100.23.
Highly Reactive Volatile Organic Compounds (HRVOCs): 100.2 pounds
Carbon Monoxide: 1,419.0 pounds
NOx: 261.0 pounds
Particulate Matter: 49.0 pounds
Volatile Organic Compounds (VOCs): 100.2 pounds

Cause: On 3/4/2014, Shell Chemical's OP-1 Unit flared process gas at the GO1 Elevated Flare due to low lube oil pressure on the process gas compressor (PGC). The main lube oil pump for the PGC had a mechanical failure and unexpectedly shutdown, resulting in the shutdown of the PCG.

Followup: Yes

Notes: Immediately, feed was safely removed from the OP-1 PGC and once the failure was identified, the feed was removed from the OP-1 furnace to repair the PGC. To prevent the recurrence of this incident, the failed mechanical components of the affected lube oil system of the PGC were repaired and the OP-1 Unit was safely restarted and returned to normal operation on 3/14/2014.
Carbon Monoxide: 5,842.0 pounds
Nitrogen Oxide: 1,074.0 pounds
Particulate Matter: 202.0 pounds
Volatile Organic Compounds (VOCs): 673.0 pounds
Benzene: 4.0 pounds


Relief valve located in OL-5
Cause: Shell Chemicals OL5 Unit released low pressure stripper bottoms material (benzene) to the concrete slab from the bellows on a relief valve (RV) in OL5. Operations immediately blocked in the RV and began to clean up the spill.

Followup: No

Notes: Data calculations and investigations are still ongoing. The report indicates that Shell would provide an update report within 60 days of the incident date on 1/6/14. As of 9/5/2014 that update has yet to be provided.