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|LDEQ Accident Number
|Point Source(s)||Notes||Amount of Release|
|Heat Exchanger in the Distillate Hydrotreater (DHT) Unit||Cause: weld failure- release came from a small hole in the side of a heat exchanger in the Distillate Hydrotreater (DHT) Unit.|
Followup: No Information Provided
Notes: There is no information as to whether this incident was preventable or not. Remedial Measures -the distillate hydroeater was removed from service and the exchanger was sent off for failure evaluation. The exchanger is scheduled to be repaired and returned to the plant in about 10 days. At that time, the Distillate Hydroeater will be returned to service.
|discharge piping of #2 HiJet|
discharge piping of #2 HiJet and North Flare
|Cause: Valero experienced excess emissions of hydrocarbon vapors and H2S from a pin-hole leak on the discharge piping of the #2HiJet. The #2 HiJet collects low pressure sour gas from several units in the refinery, compresses it, and routes it to amine treatment for use in the refinery fuel gas system.
In the final written notification dated March 11, 2013, Valero determined the root cause to be inadequate system design for corrosion prevention. The leak was caused by pitting corrosion on a piping elbow that was installed in 2010. This short service life indicates an aggressive corrosion mechanism that was not originally anticipated by Valero. Valero conducted ultrasonic and radiography surveys of this line and discovered lower than expected wall thickness in some areas and debris or sludge building obstructing flow in several locations. Low points allowing moisture and solids buildup can cause areas of aggressive corrosion in wet, hydrogen sulfide service. Valero also believes that the pipe metallurgy in this case, carbon steel, should be re-evaluated for fitness for service under these particular process conditions.|
Notes: Valero quickly diverted the gases normally collected by the #2 HiJet to the flare and shut down the #2 HiJet. Valero then reduced charge rates of the affected units to minimize SO2 emissions at the flare and began the process of transferring some of the diverted gases to the #1 HiJet for recovery. The #1 HiJet has a lower capacity than the #2 HiJet and cannot take all the gases collected by the #2 HiJet. The Vacuum Unit Hotwell Offgas remained in the flare and lean amine to the Hotwell Offgas Scrubber was maximized to reduce SO2 emissions at the flare. Valero discovered that the valve separating the leaking pip and the #1 Amine Low Pressure Knock Out Pot was leaking by and sour gas continued to leak to the atmosphere. Valero installed a temporary hose upstream of the leak to allow the leaking section of the piping to be pressurized with Nitrogen and swept to the flare from a point downstream of the leak. Within minutes of starting the Nitrogen sweep, H2S was no longer detected in the area and the Total Sulfure Analyzer on the flare indicated a significant increase in the flare line. This caused SO2 emissions at the North Flare to exceed RQ. Valero installed a clamp on the leaking section of the pipe and restarted the #2 HiJet Valero issued a second and final follow up report to this incident on March 11, 2013 in which Valero determines the root cause of the release to be inadequate system design for corrosion prevention and believes pipe metallurgy should be re-evaluated.
|no information given||Cause: Elevated flare was experienced. The facility was performing a shutdown procedure which utilized liquid nitrogen for purging of vapors and reactor cool down. The purged vapors and nitrogen were supplemented with refinery fuel gas in order to ensure combustion at the flare, resulting in a higher than normal flare.|
Notes: LDEQ received a citizen complaint regarding flaring and an odor at 9:31 pm on 1/15/2012 during which time Valero Refinery experienced an elevated flare. No reportable quantities were exceeded.
|South Flare (EQT 0049, EPN 3-77)||Cause: Valero exceeded the reporting threshold for flammable gas emissions at the South Glare due to a loss of flame. Valero had recently shut down a Diesel Hydrotreating Unit and was purging the unit with Nitrogen to the South Flare. The pilot flame sensor alarmed int the Control room and personnel visually inspected the South Flare and discovered that the flame had been extinguished. Valero stopped the Nitrogen flow and attempted to relight the South Flare, but was delayed because electrical power to the ignition system was off. Valero quickly restored electrical power and re-lit the flare. The pilot flame sensor alarmed cleared and visual evidence of a flame was observed.|
Notes: Valero stopped the Nitrogen flow and re-lit the South Flare. Valero provided verbal notification within one hour of exceeding the reportable quantity for flammable gas. Valero received no citizen complaints and did not conduct a downwind ambient air monitoring. The incident is under investigation so no specific plan of action has been put into effect to prevent recurrence.