ENTERPRISE PRODUCTS OPERATING LLC

Incident Narrative

METALLURGICAL FAILURE ANALYSIS WAS PERFORMED AFTER A HEDLAND-BRAND FLOW INDICATOR FAILED IN THE 20-INCH SEDGWICK LATERAL THAT NORMALLY CARRIES LIQUEFIED PETROLEUM GAS, GASOLINE, DIESEL, AND OTHER REFINED PRODUCTS. THE FLOW INDICATOR WAS INSTALLED IN 2007 AND LEAKED IN FEBRUARY 2011. THE ANALYSIS INCLUDED VISUAL EXAMINATION, ANALYSIS OF DEPOSITS AND CORROSION PRODUCTS, DISASSEMBLY AND SECTIONING, ABRASIVE BLASTING, STEREOMICROSCOPY, CHEMICAL ANALYSIS, AND ELECTRON MICROSCOPY. THE FAILURE WAS CAUSED BY SEVERE INTERNAL CORROSION, WHICH REDUCED THE WALL THICKNESS OF THE 2024 ALUMINUM ALLOY BODY TO THE POINT THAT IT COULD NOT WITHSTAND THE PRESSURE OF THE FLUID. THE FLUIDS THAT NORMALLY FLOW THROUGH THE FLOW INDICATOR ARE NOT CORROSIVE TO ALUMINUM. THE MATERIAL RESPONSIBLE FOR THE CORROSION WAS MOST LIKELY A CONTAMINANT THAT HAD RECENTLY BEEN REMOVED FROM THE BOTTOM OF AN UPSTREAM TANK. THIS CONTAMINANT CORRODED THE ALUMINUM LEGS THAT SUPPORTED THE ROOF OF THIS TANK AND REPORTEDLY FLOWED THROUGH THE FLOW INDICATOR. THE PH OF THE DEPOSITS/CORROSION PRODUCTS WAS MODERATELY ALKALINE. THE DEPOSITS/CORROSION PRODUCTS CONTAINED SIGNIFICANT CONCENTRATIONS OF SODIUM AND SULFUR. THE CONTAMINANT COULD HAVE CONTAINED SODIUM HYDROXIDE, WHICH IS HIGHLY CORROSIVE TO ALUMINUM. THE CORROSIVE CONTAMINANT COULD HAVE ALSO BEEN SODIUM DITHIONITE OR ANOTHER SODIUM-SULFUR COMPOUND. IF ANY OF THE CONTAMINANT IS STILL AVAILABLE, IT COULD BE CHEMICALLY ANALYZED TO IDENTIFY THE SPECIFIC COMPOUNDS THAT ARE PRESENT. THIS INFORMATION COULD BE USED TO IDENTIFY THE SOURCE OF THE CONTAMINANT AND PREVENT FUTURE ACCUMULATIONS IN THE STORAGE TANK. OTHER EQUIPMENT THAT WAS EXPOSED TO THE CONTAMINANT SHOULD BE INSPECTED TO INSURE THAT EXCESSIVE CORROSION DID NOT OCCUR.