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ExxonMobil Chemical Plant (286), Baton Rouge

Causal Factor: Process Upset

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

Propane safety valve
Cause: Propane safety valve released due to compressor upset.

Followup: No

Notes: They expected to exceed RQ for benzene and VOCs. They returned it back to normal conditions. Amount of VOC's released is unknown.
Propane: 23,000.0 pounds


Cause: Compressor tripped off.

Followup: No

Notes: It was diverted to secure and took it out of the flare.
Ethylene: 121.0 pounds
Nitrogen Oxide: 65.0 pounds
Nitrogen Dioxide: 7.0 pounds

wastewater drier
Cause: Bypass of a control device when wastewater drier vented to the atmosphere instead of to the flare system.


Notes: Amount of VOC's released is unknown.


Cause: A compressor tripped resulting in the emission of the gases to the air.

Followup: No

Notes: They have restarted the compressor.
Benzene: 20.0 pounds
1,3-Butadiene: 20.0 pounds

Cause: had a flare event associated with RTO3 upset.


Notes: May have exceeded RQ's.
Butadiene: 0.7 pounds
Nitrogen Oxide: 45.0 pounds
Volatile Organic Compounds (VOCs): 102.5 pounds

Cause: They had a failure on a control valve, causing a safety valve release to the flare. The failure was due to a system overpressure.


Notes: The flaring has stopped. The control valve is being repaired.
Nitrogen Oxide: 34.3 pounds
Ethylene: 10.0 pounds
Ethane: 0.9 pounds
Carbon Monoxide: 1.0 pounds

Furnace stack
Cause: Feed upset caused smoking furnace stack.

Followup: No

Notes: Furnace stack was smoking creating opacity issues. Exxon said this is a permit deviation. A feed upset caused the problem.Exxon says no RQ exceedences. Amount of methane and smoke released is unknown.


Storage tank
Cause: The cause of the release was pressure in the feed tanks at the Waste water improvement unit.

Followup: No

Notes: A storage tank vented for 16 m. The cause of the release was pressure in the feed tanks at the waste water improvement (WILA) unit exceeded the vacuum vent setting for 14 m. The light material entered the flare knock out drum at the Olefins unit through a safety valve bypass which was left open inadvertently during the start up after Gustav. Manual error is the root cause. LDEQ said they would take this up at the next inspection. Exxon's written report was received on 10/6/08.
Isoprene: 100.0 pounds
1,3 Pentadiene: 191.0 pounds
Flammables: 3,139.0 pounds
Butadiene: 36.0 pounds
Benzene: 548.0 pounds

Storage tank #8 in WILA
Tank 8
Tank 9

Followup: No

Notes: Storage tank 8 in WILA vented from unit upset. Pressure vacuum setting on feed tanks in the WILA unit exceeded for 10 min and released the listed chemicals. Several units that feed into WILA were on start up mode after hurricane Gustav. Communication between units if being reinforced.
: 40.0 pounds
: 48.0 pounds
: 4,029.0 pounds


Hydrocarbon recovery system, tanks 8 and 10
Hydrocarbon recovery system, tanks 8 and 11
Hydrocarbon recovery system, tanks 8 and 9
Tanks # 8 and 9
Cause: Pressure vacuum vent for hydrocarbon recovery on storage tanks #8 and 9 exceeded for one minute. During transfer of material to storage tanks the pressure exceeded the pressure vacuum setting and VOC's were released.

Followup: No

Notes: Pressure vacuum vent for hydrocarbon recovery on storage tanks 8 and 9 exceeded for 1 m. Two other events occurred within 24 hours of this event and will be addressed seperately. During transfer of material to storage tanks 8 and 9 at the WILA (wastewater improvement unit) the pressure exceeded the pressure vacuum setting and VOCs were released. The operations personnel immediately stopped pumping the material until the overpressure situation was resolved. They were investigating the source of volatile material in the WW. RQ exceeded for benzene and 1,3-butadiene.
Benzene: 23.0 pounds
1,3-Butadiene: 44.0 pounds


Tanks 8 and 9
Cause: The pressure feed tanks at the Waste water improvement unit exceeded vacuum setting and released hydrocarbon vapors to relieve the pressure. The cause is the material from the olefins unit flare knock out drum.


Notes: It was unexpected that this material will impact the WWIU.
Benzene: 123.0 pounds
Butadiene: 244.0 pounds
Flammables: 1,050.0 pounds

Cause: They have compressor trip. All the gas went to the flare. The unit is being depressured.

Followup: no

Notes: Event was ongoing.
: 700.0 pounds


Safety valve
Cause: Safety valve released into vent stacks causing a fire. Unknown what the chemical is.

Followup: no

Notes: The valve was blocked away from the vent stack at 625pm.
: 880.0 pounds
: 1,295.0 pounds
: 10.0 pounds

Cause: ExxonMobil had an upset on the hydrocarbon unit. They had to shut down a compressor. The gas from the compressor was sent to the flare.

Followup: No

Notes: Delay in notification because they didn’t get the data until the afternoon. No additional information given. Material did go offsite. Related to 104990. See comments under that incident.
Sulfur Dioxide: 700.0 pounds

Cause: A flare gas compressor tripped. This in turn caused flaring.

Followup: No

Notes: Not a reportable incident as it is covered under permit but was a reportable to state police as Nox exceeded their RQ of 10 lbs.


Cause: They lost an analog output card on a control system Off spec. Gasses went tot flare. Control valves and their by pass cause the system to go off spec. This caused them to flare the materials.


Notes: The release is ongoing until they can bring things back on line. Materials released will be tracked against 5 yr rolling average for the Sp. Condition. Amount of nitrogen oxide released is over 70 pounds.
Nitrogen Oxide: 70.0 pounds
Ethylene: 250.0 pounds

Storage tank
Cause: Pressure vapor vent release on storage tank.

Followup: No

Notes: Greater than 1000 lbs of flammable vapor were released, calculations are estimates. The incident was caused by a pressure vapor vent release pressure on the storage tank. They stopped the system completely. It is cleared up now and back in service.
Benzene: 55.0 pounds
Butadiene: 55.0 pounds
Flammable Vapor: 1,000.0 pounds


WILA tanks #8 and 9
Cause: The release was caused by the pumping of low flash material into WILA Tanks 8 and 9. The material evolved a greater amount of vapor than the tank's vapor recovery system could manage. The evolution of the vapor caused the pressure in the tanks to exceed that of the pressure vent set point.

Followup: No

Notes: Introduction of low flash point material into these tanks was immediately halted. They could not expect the flash material to evolve too much vapors. Tanks could not handle the vapors and valve lifted. Operators will be trained to communicate better to prevent the overpressure happening again. RQs exceeded for benzene. Total release of hydrocarbons is 600 pounds.
Benzene: 15.0 pounds
Isopentane: 237.0 pounds
Pentane: 159.0 pounds
Isohexane: 43.0 pounds
Hexane: 37.0 pounds
3-Methylpentane: 23.0 pounds
Methylcyclopentane: 12.0 pounds
2,3-Dimethylbutane: 11.0 pounds
2,2-Dimethylbutane: 10.0 pounds
Cyclohexane: 9.0 pounds
Heptane: 7.0 pounds
Cyclopentane: 6.0 pounds
2-Methylhexane: 6.0 pounds
3-Methylhexane: 5.0 pounds
Butane: 4.0 pounds
Toluene: 4.0 pounds
2,4-Dimethylpentane: 2.0 pounds
2,3-Dimethylpentane: 2.0 pounds
Octane: 1.0 pounds
Isooctane: 1.0 pounds
3-Methylheptane: 1.0 pounds
Methylcyclohexane: 5.0 pounds

EPLA-W compressor
stripper tower
Cause: The EPLA-West compressor trip also caused the liquid to be sent to the hydrogen compressor at the benzene hydrotreater unit (BHLA). This led to the trip of the hydrogen compressor and shut down of the BHLA unit. This unexpected shut down caused the overpressure of the stripper tower above the PSV setting

Followup: No

Notes: This incident is linked to incident #112825, which is when the safety valve on the tower blew. The benzene release to air was above RQ limit.
Benzene: 339.0 pounds
Hydrogen Sulfide: 100.0 pounds

knockout drum KD-05 on Ethylene Clarification unit
Cause: A knockout drum KD-05 on the Ethylene Clarification unit was experiencing high liquid levels. This increase in material in the quench water drum resulted in a disruption of quench water flow and led to increasing unit temperatures. Compressor HC-01 then tripped due to high temperature which caused unit material to be routed to the flare system, by design, until the compressor could be restarted.

Followup: No

Notes: To reduce the liquid levels quickly, operations personnel opened a bypass valve and routed material to a downstream quench water drum, HD-02. The RQs for ethylene, benzene, and 1-3 butadiene were exceeded. There was a light precipitation at the time of the event. This incident and responses to potential future incidents will be reviewed with operations personnel.
Ethylene: 304.0 pounds
1,3-Butadiene: 13.0 pounds
Benzene: 16.0 pounds

MVTK 08 & 09 pressure vacuum vent
Cause: Tank pressure increased and the vent opened to relieve the pressure and then closed back up.

Followup: No

Notes: No RQs were exceeded due to prompt incident response.


monoethanolamine system (MEA) at the Refinery
Cause: The plant receives feed streams from the Baton Rouge Refinery. The Refinery experienced an upset of its MEA system on 11/30 (SPOC #10-06865). This incident caused elevated hydrogen sulfide content of some of the plant's feed streams, resulting in off-specification products.

Followup: No

Notes: These materials were required to be diverted to the flare system. The plant's unit operations were adjusted to minimize emissions and incident duration. The refinery's scrubbing tower T-585 was removed from service to stabilize the MEA system, allowing the plant's feed streams to return to normal hydrogen sulfide concentrations. Successful conclusion of the Refinery incident resolved the root cause of the Chemical Plant feed stream issues. Unit procedures will be evaluated for consideration of potential incidents and responses of off-specification feed streams. RQs for ethylene and nitrogen oxide were exceeded.
Ethylene: 7,346.0 pounds
Nitrogen Oxide: 2,663.0 pounds

None Reported
Cause: Release due to system contamination.

Followup: No

Notes: Their system was contaminated. They had to shut down the flare gas compressors and recover material from the system. Flaring as a result. Report says unknown chemical release but under reportable quantity. Unauthorized Discharge Notification Report was received by Surveillance Division on 10/26/10 stating that the flare gas compressors were restarted without incident and that no release occurred.

HC-01 cracker compressor and 2nd stage safety valve

Followup: No

Notes: Two events occurred at the plant within a 24 hour period. The combined emissions from the two events exceeded the RQ for HRVOCs (ethylene and propylene). On 10/13/10 at approximately 10:44 pm, HC-01 cracker compressor tripped, and all of the Ethylene Claification-West (ECLA-W) furnace effluent was routed to the wet flare system, prompting agency notifiation (LSP incident #10-05995). The investigation showed the root cause for the event was due to a loss of lube oil pressure to the compressor during a pump swap. The emergency controls automatically shut down the compressor to prevent damage. To end the release the compessor was restarted after the lube oil pressure was returned to appropriate levels. On 10/14/10 at approximately 10:45 pm, operators identified that the HC-01 2nd stage safety valve failed to reseat properly folowing the restart of the compessor, and it was allowing additional material to enter the flare system. To end this release, the safety valve was isolated. The total HRVOC release from these two events was greater than the 100 lb RQ. The plant said they would review and/or update procedures for swapping pumps and review this incident with unit operations personnel.
Highly Reactive Volatile Organic Compounds: 107.0 pounds

Cause: Over pressure resulted in flaring of ethylene. Relief valve opened to control pressure.


Notes: Due to prompt incident response to mitigate the event duration, they have determined that no reportable quantities were exceeded. Over 100 pounds of ethylene was released.
Ethylene: 100.0 pounds

propylene compressor
Cause: Trip of propylene compressor and gas is going to the flare.

Followup: No

Notes: Originally they thought it may be greater than 100 lbs but the actual reprted release was 9 lb, below RW. Prompt shut down resulted in the release being BRQ.
Propylene: 9.0 pounds

Knock-out drum D-28
Cause: Vent on a drum popped open. Root cause was high liquid level in the drum and vent valve relieved as per design.


Notes: During normal operations, the acid gas is incinerated at furnaces F-5 and F-6. Before going to the incinerators, the liquid is removed from the steam at a knock out drum, D-28. The cause of the high liquid level is under investigation. Upon completion of this investigation, this event will be reviewed with all operating personnel and investigation recommendations will be tracked and steqarded to ensure completion. SPOC report said 126 of hydrogen sulfide were released, Exxon's report says 76.3 lbs were released. The D-28 liquid level was drained, per procedure, which allowed the vent valve to re-set in the closed position.
Hydrogen: 7.8 pounds
Carbon Monoxide: 86.7 pounds
Water: 198.5 pounds
Hydrogen Cyanide: 0.9 pounds
Carbon Dioxide: 8,296.8 pounds
Hydrogen Sulfide: 76.3 pounds

Cause: T104 Overpressured and caused emergency shut down.

Followup: No

Notes: Burning to a flare.
Propylene: 100.0 pounds
Ethylene: 30.0 pounds

HCE vacuum jet
Cause: The HCE vacuum jet went positive.

Followup: No

Notes: No additional information.
Benzene: 31.0 pounds

OXO furnace F-635
Cause: OXO furnace (F-635) experienced a loss of instrument air causing the furnace to trip. As a result o the furnace trip, the vent stream, normally combusted in the furnace, was diverted to the atmosphere.

Followup: No

Notes: No information given regarding remedial actions. This event is combined with a subsequent release LDEQ incident # 135902. Their combined release exceeded reportable quantities for flammable vapors over a 24 hour period.
Flammable Vapor: 921.0 pounds

None Reported
Cause: Chemicals flared due to unit start up.

Followup: No

Notes: Chemical released is unknown. All emissions were permitted and no reportable quantities were exceeded.

vent tanks 8 & 9
Cause: Pressure vacuum vent on a tank released to atmosphere.

Followup: No

Notes: The release was located at Tanks 8 & 9. Approximately 649 pounds of total vapor were released.
1,3-Butadiene: 2.0 pounds
Benzene: 3.0 pounds
Nitrogen: 585.0 pounds

Safety valve
Cause: Methane release occurred when a safety valve reached it's pressure setting. Released to atmosphere.

Followup: No

Notes: Due to prompt incident response to mitigate the event duration, no reportable quantities were exceeded.
Natural Gas: 79.0 pounds

vapor recovery unit
Cause: Aromatics intermittent short duration vapor recovery unit compressor tripped.

Followup: No

Notes: Steam jets were used to secure the incident.
Benzene: 10.0 pounds

PSV valve
Cause: PSV valve released gas into the air when two drums were switched and had a momentary over pressure. Approximately 3 lbs of benzene were released.

Followup: No

Notes: Due to prompt incident response to mitigate the event duration, no reportable quantities were exceeded.
Benzene: 3.0 pounds

Exxon's Baton Rouge Refinery
Cause: Flare due to an event in the adjacent refinery that caused an upset in the system.

Followup: No

Notes: An event occurred in the adjacent refinery which caused an upset in the system. This caused a release of ethylene and propylene to the flare. Plant's written report says all releases were below RQ.
Combustion Products: 290.0 pounds

Cause: Unit upset required the release of propylene to the flare system.

Followup: No

Notes: Flaring was part of online operating adjustments in lieu of shut down.


compressor MC-02
Cause: On 11/2/12, compressor MC-02 discharge casing developed a leak.

Followup: No

Notes: Sealant was pumped into the casking to isolate the leak. After further evaluation, Exxon Chemical has determined that no RQs were exceeded. Approximately 211 pounds per day of flammable vapor, 32 pounds per day of ethylene, and 26 pounds per day of propylene were released as a result of this event.


Cause: HC-01 cracker compressor tripped, and all of ECLA-W furnace effluent was routed to the flare system. The lube oil accumulator was found to have a broken bladder. The root cause of the event was due to a loss of lube oil pressure to the compressor during a pump swap.

Followup: No

Notes: To end the release, the lube oil pressure was returned to appropriate levels and the compressor was restarted. The lube oil accumulator was found to have a broken bladder. This device is designed to dampen pressure swings when the lube oil pumps are swamped. The faulty lube oil accumulator bladder has been replaced.
Ethylene: 271.9 pounds

OLA-2X gas compressor
Cause: On November 20, 2013 at approximately 2 PM, the OLA-2X gas compressor tripped due to high vibrations; causing material to be released to the site's flare gas system. Follow-up investigation results indicate that the drain line for the compressor coupling guard became plugged with an extensive amount of coke, allowing oil to build up and degrade the inside of the coupling guard. Over time, the oil degradation impinged on the coupling, causing the high vibrations. The Reportable Quantities for ethylene, propylene, butadiene, isoprene, benzene, nitrogen oxide, and sulfur dioxide was exceeded as a result of this event.

Followup: Yes

Notes: Immediately after the trip, unit shutdown procedures were executed and feed was safely removed from the unit. Air monitoring was conducted on November 20 and November 21 and all results were below the level of detection. Insulated the coupling guard drain line. Will evaluate installing a manometer on the coupling guard to attempt to measure air flow in the coupling guards and establish a monitoring program to determine if coke is accumulating in the coupling guards. Note: the initial report claims that plugged drain lines are not able to be detected or repaired, so the incident was not preventable. However, the follow-up report claims that air monitoring might detect coke accumulation and allow prevention.
Ethylene: 1,476.0 pounds
Propylene: 588.0 pounds
Butadiene: 382.0 pounds
Isoprene: 165.0 pounds
Benzene: 338.0 pounds
Nitrogen Oxide: 1,628.0 pounds
Sulfur Dioxide: 11,979.0 pounds

OLA-2X Gas Turbine
Cause: On September 29 at approximately 11:20 PM, the OLA-2X gas turbine tripped causing material to be released to the site's flare gas system. The shutdown was caused by a loss of flame in the gas turbine. Initial findings indicate that a change in power augmentation steam quality caused the loss of flame. An investigation is underway to determine the root cause of the change in steam quality.

Followup: No

Notes: Feed was safely removed from five of the seven furnaces to minimize the load on the flare system and emissions to the atmosphere. The remaining two furnaces were operated at minimal rates to minimize start-up emissions. Air monitoring was conducted on September 30, 2013 and all results were below the level of detection. This incident is under investigation to determine the root cause of the change in steam quality. Short term mitigation steps have been implemented to ensure consistent steam delivery to the gas turbine.
Ethylene: 3,456.0 pounds
Propylene: 1,376.0 pounds
Butadiene: 893.0 pounds
Isoprene: 386.0 pounds
Benzene: 792.0 pounds
Nitrogen Oxide: 3,810.0 pounds
Sulfur Dioxide: 28,041.0 pounds

Waste Water Treatment Unit
Cause: On July 29, 2013 at approximately 6:33 pm, predictive modeling showed increased benzene emissions from the Baton Rouge Chemical Plant Waster Water Treatment unit (AWT). Prior to being sent to AWT for final treatment before discharge, steam cracking furnace water effluent is stripped to recover benzene. The steam stripping distillation tower experienced abnormal operations in June as a result of internal fouling. This resulted in tower temperatures lower than the minimum temperature required to efficiently remove benzene. During this period of abnormal operations, benzene levels were higher than normal but these elevated benzene levels were not detected until routine compliance samples caught at AWT were analyzed at a third party laboratory in July. Therefore, the results of these samples were not available until after tower operations were stabilized. Initial notification indicates the release lasted for approximately 7 days. Initial notification occurred 7/29/13, incident started more than a month before, 6/17/2013. A field inspection was conducted by LDEQ Inspection Division on 8/9/13 in response to this event.

Followup: Yes

Notes: The incident was detected upon third party sample analysis of scheduled monthly environmental samples taken to track compliance with the AWT Title V permit. While the BRCP permit requires annual modeling and sampling, the site voluntarily models samples on a more frequent, monthly basis to provide a back-up monitoring program. The sample results were not available until after appropriate measures has been taken to stabilize lower operations. Stable operations were validated by samples taken on July 1, 2013 which were within historical values. The tower has been taken out of service, cleaned, and returned to service. Alarms for critical operating parameters are being updated to ensure effective benzene stripping. The sampling protocol has been modified such that ExxonMobil will receive VOC concentration within 48 hours of arrival at the third party laboratory.
Benzene: 6,577.0 pounds