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Louisiana Refinery Accident Database

Motiva Enterprises (2719), Convent

LDEQ Accident Report

Pollutants Released

Accident Classified As: Reportable Quantity

Cause of Problem: Corrosion

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.

Discharge Preventable - No

Motiva was following its existing piping inspection program at the time of the incident. Motiva is reevaluating these inspection programs based on lessons learned from this incident and will revise these programs as neccesary.

Notes/Remedial Actions

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