Home Search Emissions Pollutants About the Database

Motiva Enterprises (2719), Convent

Causal Factor: Corrosion

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

Hydrotreating Unit #2
Cause: The tubing failed due to its susceptibility to Chloride cracking. The combination of Chlorides, H2O, stress, and stainless steel tubing created a condition that allowed stress corrosion cracking to occur in the Inside Diameter (ID).

Followup: Yes

Notes: The immediate air was evacuated, as IES and Motiva's emergency response staff responded to the incident. Air monitoring detected no off site impact. Release was stopped via water suppression and installation of valves at each release point. Motiva will verify that the material to replace the tubing is appropriate in resistance to stress, H2O and Chloride cracking. Will determine the presence of the tubing on HTU-2 documenting the items for replacement. Will establish a risk assessment criteria to identify and replace tubing that is high risk for ID initiated stress and corrosion cracking. Follow-up report: reported relese did exceed the 1,000 pound RQ for flammable gas
Hydrogen: 5,910.0 pounds

Alkylation Unit
Cause: Leak in the piping downstream of a static mixer near the depropanizer in the alkylation unit. Caustic is injected upstream of the static mixer to neutralize sulfuric acid in the static mixer. There is a bypass line for bypassing the mixer. Since the bypass line was not being used at the time of the incident, caustic was not being injected directly into the bypass line. A small amount of sulfuric acid leaked through a closed valve and accumulated in a dead leg in the bypass line. Over time, the material in the dead leg thinned until it failed, causing the leak.

Followup: Yes

Notes: Telephone report indicated both flammable gas and sulfuric acid mist were being released, but after investigation determined that release point was downstream of a static mixer, where caustic is used to neutralize any residual sulfuric acid in the process. Air monitoring around the hot spot were zero. Installed a clamp on the leak to completely stop it. Installed blinds and removed equipment to isolate the leaking line. Reevaluating inspection programs based on lessons learned from this incident. Motiva determined that the bypass line is not necessary and has removed most of this bypass line
Flammable Gas: 2,758.0 pounds

line at metering station at West Tank Farm
Cause: Leak developed in a dead leg in a line in the West Tank Farm at a metering station, which caused crude oil to spill on the soil and concrete surface. Exceeded RQ.

Followup: No

Notes: Shut down incoming pipeline, isolated line, deployed booms and placed 5gal bucket under leak, cleaned with vacuum truck, removed contaminated soil, repaired line. "This incident occurred at an interface between equipment owned and operated by Shell Pipeline and Motiva. Motiva will implement a 'bridging document' between Shell Pipeline and Motiva that will clearly identify accountabilities and responsibilities for inspection and maintenance of this interface."
Crude Oil: 126.0 gallons

Plant 21 Pipeway
Cause: hole appears to result from corrosion of exterior insulation.

Followup: No

Notes: The section of HSR line has been replaced. Motiva will remove insulation and inspect the HSR line for addition corrosion threats.
Heavy Straight Run Naphtha: 126.0 gallons

West Tank Farm
Cause: under deposit corrosion inside 36 crude line creates a 1/4 inch ho

Followup: No

Notes: The hole has been clamped and a slip blind put in place at the upstream block valve to further isolate the line from the product.
Crude Oil: 420.0 gallons

Process Unit: Catalytic Reformer Unit
Cause: line leak developed due to internal corrosion

Followup: No

Notes: Motiva Pressure Equipment Integrity Group has been tasked with evaluating this line and making recommendations that will reduce the likelihood of a recurrence.
Hydrogen: 167.0 pounds
Methane: 7,809.0 pounds
Ethane: 706.0 pounds
Ethylene: 301.0 pounds
Propane: 820.0 pounds
Propylene: 106.0 pounds
Butane: 449.0 pounds
n-Butane: 217.0 pounds
Isobutylene: 19.0 pounds
trans-Butylene: 11.0 pounds
cis-Butylene: 7.0 pounds
Isopentane: 61.0 pounds
Pentane: 49.0 pounds
Hexane: 109.0 pounds
Nitrogen: 1,335.0 pounds
Carbon Monoxide: 113.0 pounds
Carbon Dioxide: 101.0 pounds


VPS-1 Crude transfer line
Cause: Motiva operations discovered oil on the ground beneath a pipe rack located near Avenue C in the west section of the tank farm between tanks 20D-31 and 20D-46. The source was determined to be a leaking 10 inch VPS-1 Crude transfer line. The spilled material remained within the boundary of the rank die area, therefore there were no offsite impacts as a result of the incident.

Followup: No

Notes: A Motiva operator isolated the leaking section of the pipe. The spilled material remained within the boundary of the tank dike area. The free liquid was routed from the tank dike to the dirty oil sewer where it is directed to API. An on-site contractor that specializes in spill clean-up responded and the recovered contaminated soil was placed in roll-off boxes for proper disposal. The remediation process was completed with the addition of Nitrogen-enriched Micro Sorb to the ground to further promote biodegradation of any low level residual hydrocarbons. The leaking section of the line remains out of service and will be permanently removed. The remaining portion of the crude transfer line will be inspected by the pressure integrity department to identify any other areas of concern. Oil cleaned up through a vacuum truck and absorbent pads.
Crude Oil: 84.0 gallons

Flare #2
VPS-2 supply line
Cause: The supply line for the VPS-2 atmospheric bottoms sample station was lined-up to the discharge of the atmospheric tower bottoms pump. The unit was in operation and the pump was online with a discharge pressure of approximately 145 PSIG. At approximately 4:00 am on October 1, 2012 the sample supply line was breached. The auto ignition temperature of this stream was approximately 500 deg F, and the operation temperature was 700 deg F. These conditions were enough to cause ignition and support the chemical reaction needed to sustain the fire. The piping where the fire began was inspected and a beach was found on top of the sample supply line. The breach consisted of a "flap" of metal which had separated from the pipe revealing a 1" by 1 3/4" opening. The A106B carbon steel piping of the sample line had been exposed to process material containing 4% sulfur, operating at 700 deg F, and had been so for a sufficiently long period creating sufficient conditions for the mechanism to occur. The change in metallurgy from the process line (9 Cr steel) to the sample station line (carbon steel) appears to have made the sample line piping more vulnerable to corrosion. Furthermore, a review of the incident revealed the root valves of the sample line were 12'-15' above grade and had to be accessed using a portable ladder. These valves were difficult to operate even when temporary access means were provided. A new sample schedule had been issued, requiring the sample to be taken twice a week, requiring even more access to the valves. The practice became to leave the valves open, thereby leaving the piping exposed to the corrosive environment. This ultimately accelerated the corrosion rate in the system.

Followup: Yes

Notes: The crude oil released during the fire that was deposited on the unit slab and nearby equipment. In addition, small particles of entrained oil in the fire water mist migrated downwind and deposited outside the unit boundary on Motiva propery. These off-unit areas were cleaned, excavated and/or immobilized/degraded. There were no oil residues from the fire observed off site. Site perimeter air monitoring was conducted for %O2, LEL, H2S, CO and SO2. All readings were normal ranges or non-detectable. Motiva Operations immediately initiated an unplanned but controlled shutdown of VPS-2. Excess process gases associated with the shutdown were routed to the refinery's flare system for destruction. The sample station and piping where the breach occurred has been removed and a review is being conducted site-wide for other locations that may have a similar threat/issue. Sample station design standards are being expanded to incorporate a strategy for managing the metallurgy of sample stations with respect to the metallurgy of the process line. In the 7-day letter, Motiva initially estimated the amount of crude oil released to be 6.5 bbls; they have now determined that 73.8 bbls were actually released during this incident. An estimated 68.6 bbls were consumed by the fire, 1.2 bbls released to the unit slab, and 4 bbls were released in areas downwind of the unit slab, but on Motiva property. On the LDEQ verbal report, it is noted that NOx exceeded reportable quantity and went to flare #2; this is not mentioned in any of the follow-up reports submitted by Motiva following this incident.
NOx: 10.0 pounds
Crude Oil: 3,099.6 gallons

H-Oil Unit
Cause: Potential H2S release in the H-Oil Unit when corrosion under insulation contributed to degradation of carbon steel instrument tubing. Initial notification reported a potential exceedance of the 100 lb reportable quantity (RQ) for H2S. Refinery letter updates that this RQ was not exceeded.

Followup: No

Notes: Release was determined to be below reportable quantities. No remediation actions were described.