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Valero (26003), Norco

Releases of Isobutane

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

outlet line of the C3C4 KOH Dryers (V-17-05A/B)
Cause: A hole was found in the LPG line that feeds the T-17 bullets. The hole was 1/4 inch.

Followup: Yes

Notes: Valero responded to the leak found by submerging the line with fire water to suppress vapors, isolating the leak, and depressuring the line/vessel to flare. The failed section of the pipe was replaced and the line returned back to service. The isolationand depressurization lasted approximately 1h 15m.
834.0 pounds

Cause: A higher capacity pump was used on June 17th, the night before the incident, to pump down the level of spent sulfuric acid in the alkylation unit degassing drum to T-50-3 and exceeded the capacity of the tank's thermal oxidizer (TO). When the pressure exceeded the PVRV set point (24 oz/sq inches) the accumulated gases were vented to the atmosphere. Tk50-3

Followup: Yes

Notes: The flow of spent acid from the alkylation unit to T-50-3 was stopped allowing the pressure within the tank to decrease below the set point of the PVRV. The PVRV was subsequently monitored to check that it had completely closed after the pressure decreased to normal levels. Valero identified the following corrective actions: (1) Install downstream flow monitor on spent acid rundown line so operators can monitor the rate of spent acid rundown. (2) Reroute acid pot flush from the degassing drium to the spend acid settler to reduce hydrocarbon carry through. (3) Maintain level in the spent acid degassing drum at 20% or greater when pumping to T-50-3. (4) Set alarm on the spent acid Coriolis meter density to stop or reduce spent acid flow when hydrocarbon carry through appears likely. (5) Evaluate increasing PVRV set pressure from 1/5 psig on T-50-3. (6) Evaluate increasing the size of the TO on T-50-3 to handle additional vapor load.
27,893.0 pounds

Coker LPG line
Cause: Valero had blinded and de-inventoried the Coke LPG line as part of a project to elevate the Prospect Road pipe bridge that connects their East Plant and West Plant. The blinds were removed several days prior to the incident but valves in the pipe system remained closed. Valero believes that gas leaked by one of the valves and accumulated in a section of pipe after the blind had been removed on the West Plant side of the project area thus trapping gas between two closed valves. On the day of the incident, the project operator opened the downstream valve in the pipe bridge that was closest to the FCCU in order to commission a new section of pipe; the upstream valve remained. When the valve was cracked open, gas that had accumulated in the pipe leaked out into the FCCU which was undergoing construction at the time of the incident.

Followup: Yes

Notes: Coker liquified petroleum gas (LPG) which is composed mainly of butenes and propenes was released from pipe openings in the FCCU area and dispersed. Emissions were minimized by isolating the coker LPG line. Valero identified the following corrective actions and target completion dates were identified as a result of the root cause failure analysis of this incident: (1) Issue safety alert on this incident to all personnel (2) Review incident with operators and discuss need for good communications when lining up piping to units (3) Develop a battery limits blind list for the FCCU for use during future turnarounds (4) Develop a battery limits list for Complex III (Crude-Vacuum-Coker units) for use during future turnarounds
107.1 pounds