{"operation":"document","citation":"DCA17FP001","title":"Magellan Pipeline Anhydrous Ammonia Release","source_type":"incident","agency":"National Transportation Safety Board","status":"current","official":true,"published_on":"2021-05-18","effective_on":"2016-10-17","summary":"Pipeline occurrence. in Tekamah, NE, USA. on 2016-10-17","machine_formats":{"json":"https://regulus.evalyn.ai/document/ntsb-case-dca17fp001.json","markdown":"https://regulus.evalyn.ai/document/ntsb-case-dca17fp001.md"},"app_url":"https://regulus.evalyn.ai/document/ntsb-case-dca17fp001","source_url":"https://www.ntsb.gov/investigations/Pages/DCA17FP001.aspx","body":"NTSB investigation DCA17FP001.\n\nEvent Date: 2016-10-17\n\nEvent City: Tekamah\n\nEvent State Or Region: NE\n\nEvent Country: USA\n\nCompletion Status: Completed\n\nReport Number: PAB2001\n\nReport Date: 2020-01-29\n\nProbable cause: The National Transportation Safety Board determines that the probable cause of the pipeline rupture was corrosion fatigue cracks that grew and coalesced under disbonded polyethylene tape coating. Contributing to the location of the cracking was external loading that caused bending stress in the pipe in addition to the cyclic stresses in the pipe from the internal pressure of the ammonia transported.\n\nTier1Name: System operating\n\nTier2Name: Pressure/flow/temp event\n\nTier1Name: System operating\n\nTier2Name: System warning/signal\n\nTier1Name: System operating, changing flow/pressure\n\nTier2Name: Emergency shutoff\n\nTier1Name: System operating\n\nTier2Name: Product leak/release\n\nTier1Name: System operating\n\nTier2Name: Pipe structural malfunction/failure\n\nFinding Tier1Name: Pipeline\n\nFinding Tier2Name: Pumps/compressors\n\nFinding Tier3Name: Pump/compressor controls\n\nFinding Modifier Name: Incorrect use/operation\n\nFinding Report Text: Pipeline - Pumps/compressors - Pump/compressor controls - Incorrect use/operation\n\nFinding Tier1Name: Pipeline\n\nFinding Tier2Name: Pipeline structure\n\nFinding Tier3Name: Pipe\n\nFinding Modifier Name: Incorrect use/operation\n\nFinding Report Text: Pipeline - Pipeline structure - Pipe - Incorrect use/operation\n\nFinding Tier1Name: Environment/Infrastructure\n\nFinding Tier2Name: Conditions/weather/phenomena\n\nFinding Tier3Name: (general)\n\nFinding Modifier Name: Contributed to outcome\n\nFinding Report Text: Environment/Infrastructure - Conditions/weather/phenomena - (general) - Contributed to outcome\n\nFinding Tier1Name: Pipeline\n\nFinding Tier2Name: Pipeline structure\n\nFinding Tier3Name: Pipe coatings/anti-corrosion\n\nFinding Modifier Name: Damaged/degraded\n\nFinding Report Text: Pipeline - Pipeline structure - Pipe coatings/anti-corrosion - Damaged/degraded\n\nFinding Tier1Name: Pipeline\n\nFinding Tier2Name: Pipeline structure\n\nFinding Tier3Name: Pipe\n\nFinding Modifier Name: Fatigue/wear/corrosion\n\nFinding Report Text: Pipeline - Pipeline structure - Pipe - Fatigue/wear/corrosion\n\nOfficial NTSB investigation data. NTSB findings determine probable cause and make safety recommendations; they do not adjudicate civil liability or regulatory violations.\n\nWhat Happened\nOn October 17, 2016, shortly after 9:00 p.m. local time, an 8-inch-diameter underground transmission pipeline ruptured and released 2,587 barrels (108,654 gallons) of liquid anhydrous ammonia on private property adjacent to milepost (MP) 263.32 on County Road P in Burt County, near Tekamah, Nebraska. The pipeline was owned and operated by Magellan Midstream Partners, LP, (Magellan). Upon release and exposure to the atmosphere, the ammonia vaporized and produced a toxic plume. A local resident who had left his home to investigate the accident scene died of respiratory failure due to exposure to the ammonia vapor; additionally, two people sustained minor injuries. A total of 29 households, involving 49 people, were evacuated. U.S. Highway 75, a main roadway in the area, was closed for several days.\nThe ammonia pipeline was operated and monitored from a control center located in Tulsa, Oklahoma. Low pressure alerts were received in the control center at 9:03 p.m., and a rupture alarm first occurred at 9:14 p.m.At 9:21 p.m., control center personnel received a third-party report of strong ammonia odor and a vapor cloud located 8.5 miles north of Tekamah, Nebraska.\n\nWhat We Found\nWe determined that the probable cause of the pipeline rupture was corrosion fatigue cracks that grew and coalesced under disbonded polyethylene tape coating. Contributing to the location of the cracking was external loading that caused bending stress in the pipe in addition to the cyclic stresses in the pipe from the internal pressure of the ammonia transported.\n\nPAB-20-01\n<<<PAGE 1>>>\n\nNational Transportation Safety Board\nPipeline Accident Brief\nMagellan Pipeline Anhydrous Ammonia\nRelease\nNear Tekamah, Nebraska\nOctober 17, 2016\nThe Accident\nOn October 17, 2016, shortly after 9:00 p.m. local time, an 8-inch-diameter underground\ntransmission pipeline ruptured and released 2,587 barrels (108,654 gallons) of liquid anhydrous\nammonia on private property adjacent to milepost (MP) 263.32 on County Road P in Burt\nCounty, near Tekamah, Nebraska.1 The pipeline was owned and operated by Magellan\nMidstream Partners, LP, (Magellan). Upon release and exposure to the atmosphere, the ammonia\nvaporized and produced a toxic plume. (See figure 1.) A local resident who had left his home to\ninvestigate the accident scene died of respiratory failure due to exposure to the ammonia vapor;\nadditionally, two people sustained minor injuries. A total of 29 households, involving 49 people,\nwere evacuated. U.S. Highway 75, a main roadway in the area, was closed for several days.2\nThe ammonia pipeline was operated and monitored from a control center located in Tulsa,\nOklahoma. Low pressure alerts were received in the control center at 9:03 p.m., and a rupture\nalarm first occurred at 9:14 p.m. At 9:21 p.m., control center personnel received a third-party report\nof strong ammonia odor and a vapor cloud located 8.5 miles north of Tekamah, Nebraska.\n1 Tekamah, Nebraska, is located about 8 miles directly south of the accident site, and Decatur, Nebraska, is about\n6.5 miles directly north.\n2 For more detailed information about this accident investigation, see the the public docket at\nwww.ntsb.gov/investigations/dms.html and search for accident number DCA17FP001.64660 NTSB/PAB-20/01\n\n<<<PAGE 2>>>\n\nAnhydrous Ammonia Release\nFigure 1. Aerial photograph of active anhydrous ammonia release with map insert showing\nrelease location. (Source: Magellan.)\nActivities at Time of Accident\nDuring the early evening of October 17, 2016, no operational issues were reported by the\non-duty controller at shift change, and operational records did not indicate any operating\nirregularities. About 9:00 p.m., the controller was pumping ammonia north on the pipeline system\nfor a customer delivery. At 9:03:45 p.m., the ammonia pipeline pressure dropped 42 psi on the\nsuction side of the Herman pump, which was located south of the Burt County line and near where\nthe release occurred. Then, at 9:03:49 p.m., a 68-psi pressure decrease occurred on the discharge\nside of the Herman pump. These events triggered an alert in the control center and led to an\nautomatic shutdown of the Herman pump.\nAt 9:11:38 p.m., the on-duty controller contacted the leak detection analyst (LDA) after\nreceiving additional alerts and notices from the control system. The on-duty controller told\nNational Transportation Safety Board (NTSB) investigators that he did not initially think he had a\nrupture. Rather, he stated that he contacted the LDA to seek an opinion on why the system appeared\nto be losing pressure. The controller wanted to determine if the alerts were caused by an irregularity\nin the Magellan software.\nAt 9:14:40 p.m., the on-duty controller received an alarm indicating that a rupture had\noccurred. The SCADA controller immediately began to shut down the ammonia pipeline. At\n2\n\n<<<PAGE 3>>>\n\nAnhydrous Ammonia Release\n9:17:15 p.m., another leak alert was received after the controller had initiated a pipeline system\nshutdown.\nPost Release Actions\nFollowing the 9:14:40 p.m. alert, Magellan’s on-duty controller began isolating the pipeline\nrupture by shutting down pumps and closing valves. The sequence of valves closed to stop the\ndischarge of ammonia is shown in figure 2.\nFigure 2. Magellan ammonia pipeline showing valves located at mileposts surrounding the\nrelease site.\nEmergency Response\nAt 9:26:23 p.m., Magellan’s on-duty controller issued a Code Red, which initiated\nemergency response actions by Magellan staff, and established a phone bridge at 9:35:10 p.m. for\n3\n\n<<<PAGE 4>>>\n\nAnhydrous Ammonia Release\ncommunications among responders.3 A Magellan operations control relief controller notified the\nBurt County Sheriff’s office at 9:35:50 p.m. and advised that 500 barrels of ammonia had been\nreleased and to avoid gas clouds.\nThe community emergency response involved the Tekamah Fire and Rescue Association\n(TFRA) and the Burt County Sheriff’s Department. About 10:33 p.m., the TFRA fire chief assumed\nthe role of incident commander and developed a tactical response plan, which involved isolating\nan area on County Road P between County Road 32 and U.S. Route 75. They planned to evacuate\nanyone found in that area. The TFRA dispatched fire and rescue resources to the scene. The\nsheriff’s 911/dispatch center made phone calls to residents within an initial 1/2-mile evacuation\nzone downwind of the release.\nA Magellan employee was designated to provide technical support to emergency\nresponders. The Magellan employee recommended a 2-mile evacuation distance and took over the\nincident command. The TFRA fire chief requested mutual aid from the Decatur Rural Volunteer\nFire Department. Personnel from both agencies conducted the evacuation by door-to-door\ncanvasing of residences. Afterward, the Nebraska Hazardous Incident Team (hazardous materials\nrelease response unit of the Nebraska State Patrol) arrived to assist with the emergency response.\nPipeline Operation\nMagellan is an interstate pipeline operator that primarily transports, stores, and distributes\ncrude oil and refined petroleum products. In 2016, Magellan had more than 1,700 employees in 23\nstates, with about 9,700 miles of oil and petroleum refined product pipelines and 56 storage\nterminals, throughout 15 states, extending from the Gulf Coast throughout the middle of the United\nStates to Minnesota. Among these assets, Magellan operated an 1,100-mile common carrier\nammonia pipeline 4\nMagellan’s ammonia pipeline system has three branches that originate in Borger, Texas,\nVerdigris, Oklahoma, and Enid, Oklahoma, and terminate in Mankato, Minnesota. Liquid\nammonia is injected into the pipeline from third-party production facilities and is transported to\nagricultural centers in Iowa, Kansas, Minnesota, Nebraska, Oklahoma, and South Dakota. The\nammonia is used to produce nitrogen compounds such as urea, ammonium nitrate, ammonium\nphosphate, and ammonium sulfate.\nMagellan’s ammonia pipeline was installed in 1968. The pipeline has an outside diameter\nof 8.625 inches and, in the area of the release, was buried 48 inches below grade. The pipe wall\n3 The Code Red procedure provides a play-by-play set of actions for Magellan staff, on-scene Magellan parties,\nand subcontract support staff. The Code Red procedure includes the roles and responsibilities of each participant from\nthe onset of a release to the point the release has been neutralized. Code Red Event Procedure 9.02-ADM-011 covers\na standardized method for event response, focusing on a safe and prompt responses for the public and employees,\nenvironmental protection, minimization of release volume, containment of release volume, and containment in\nprimary vessel (pipeline, tank, etc.). The procedure addresses SCADA-indicated pipeline ruptures and notifications\nreporting pipeline fire, explosion, or vapor cloud that leads to suspicion or confirmation of a pipeline rupture or high-\nrate release.\n4 Common carrier pipelines provide transportation services for any person or company, and the carriers are\nresponsible for the loss of goods during transport as authorized by a regulatory body such as the Federal Energy\nRegulatory Commission or by state agencies. Private carrier pipelines are not authorized to provide services to the\npublic.\n4\n\n<<<PAGE 5>>>\n\nAnhydrous Ammonia Release\nthickness was 0.156 inch. The maximum operating pressure (MOP) at the release location was\n1,198 psig.\n5 The pipeline was manufactured by Lone Star Steel in accordance with American\nPetroleum Institute (API) Specification 5L using Grade X46 steel and a low frequency electric\nresistance longitudinal seam welding process. The pipeline had an impressed current cathodic\nprotection system as well as a field-applied polyethylene tape wrap to mitigate external corrosion.\nThe release occurred on a segment of the ammonia pipeline known as the West Leg.\nMagellan records indicated that the West Leg in Burt County has had multiple leaks and repairs\nsince it was installed. In April 1984, 168 gallons of ammonia were released due to a defective pipe.\nBetween 1988 and 1990, five minor ammonia leaks occurred that required pipeline repairs. From\nMay 1993 to October 1994, there were three pinhole leaks that released 221 gallons of ammonia.\nInspection of Damaged Pipeline\nOn October 20, 2016, the ruptured section of ammonia pipeline was unearthed. The pipe\nhad fracture on its underside (6 o’clock position) and exhibited downward bending proximal to the\nfracture location. (See figure 3.) The fracture followed the spiral seam pattern of the field-applied\npolyethylene tape wrap (See figure 4.) The fracture ran roughly 45° from the longitudinal axis of\nthe pipe in a spiral path. The fracture had sawtooth-like features, with numerous short cracks\nmerging into the main fracture. The total length of the fracture was 11 7/8 inches, and the widest\nopening of the fracture was 0.19 inch. About a 60-inch section of the pipeline containing the\nfracture was removed and was shipped to the NTSB Materials Laboratory in Washington, DC for\nfurther examination.\nPortions of the protective polyethylene tape coating adjacent to the fracture were displaced\nfrom the pipe but recovered during the investigation. When loose pieces of tape were positioned\non the pipe surface, the fracture aligned with the edges of successive windings of the tape, where\nthe tape overlapped. Also, there were areas on the pipe segment where the tape wrap had visibly\nshifted. One area of the tape had its edges folded over, exposing the pipe surface. Brown-colored\ncorrosion was visible on the exposed pipe surface. Tenting of the tape wrap was observed\nlongitudinally along the 6 o’clock position of the pipe, roughly in line with the fracture.6\nNumerous thumbnail-shaped cracks consistent with fatigue cracks were visible on the\nfracture surfaces. The patterns were oriented such that the thumbnail-shaped cracks emanated from\nthe outside diameter of the pipe. The presence of numerous thumbnail-shaped cracks was\nconsistent with multiple initiation fatigue cracking. The deepest thumbnail-shaped fatigue crack\nextended through approximately 75 percent of the pipe wall thickness. The areas between the\nthumbnails and adjacent to the inside diameter of the pipe exhibited microvoid coalescence\nconsistent with overstress fracture. Overall, the fracture features were consistent with corrosion\nfatigue.\n5 Maximum operating pressure (MOP), as defined in Title 49 Code of Federal Regulations (CFR) §195.406, is\nthe maximum pressure permitted for normal line or vessel operation; MOP is related to pipe strength and the ability\nof a pipe to withstand internal pressure. MOP ratings are based on three factors: design pressure, hydrostatic test\npressure, or flange rating. Internal design pressure for a pipeline is determined according to an established formula.\n6 Tenting is a form of disbondment of a pipeline coating. Disbondment refers to the loss of the bond (adhesion)\nbetween a pipeline and its protective coating, which has been known to allow moisture to become trapped between\nthe surface of the pipe and the tape wrap, creating an environment that may be corrosive.5\n\n<<<PAGE 6>>>\n\nAnhydrous Ammonia Release\nApproximate\nfailure location\nAmmonia\nFlow\nFigure 3. Photograph of failed section of ammonia pipeline.\nFigure 4. Photograph of ammonia pipeline crack showing alignment with seam in protective tape\nand sawtooth crack features.\nThe residual curvature of the pipe section after removal from the pipeline indicted that the\nstress from the bending loads had exceeded the yield stress of the steel. The tensile stress from\nbending would have been the greatest on the bottom of the pipe, at the external surface, in the area\nwhere cracking initiated. The hoop stress from the MOP at the rupture location is about 70 percent\nof the specified yield stress of the steel.\n6\n\n<<<PAGE 7>>>\n\nAnhydrous Ammonia Release\nSamples were taken from the pipeline to test the chemical composition and material\nproperties (yield stress, tensile strength, and elongation at failure) of the steel. The test results were\nconsistent with the API 5L X46 specification.\nMagellan records indicate that the West Leg had been in-line inspected periodically from\n2004 to 2015 using NACE International standard practices.\n7 The last in-line inspection (ILI) run\nthrough the section of pipe where the rupture occurred was in September 2015, using magnetic\nflux leakage (MFL) measurements and smart pigging tools for detection of wall-loss corrosion and\nother indications of pipeline integrity issues.\n8 The MFL assessment used contractor-supplied\nspecifications for defect sizing for metal loss, pitting, axial grooving, circumferential grooving,\nand circumferential slotting in the pipe body and girth weld heat-effected zones.9 Technicians\nreviewed the 2015 ILI data and did not find any anomalies or indications of pipeline failures at\nthat time.\nMagellan records indicate that hydrostatic testing of the ammonia pipeline occurred from\nSeptember 2008 to January 2012. The hydrostatic tests were not required by federal regulations,\nbut Magellan nevertheless performed the conventional 8-hour test methodology recommended by\nthe Pipeline and Hazardous Materials Safety Administration (PHMSA) as well as spike tests.\n10\nThe hydrostatic tests revealed five leaks, two of which were attributed to stress corrosion cracking.\nMagellan repaired these leaks prior to the accident.\nPostaccident Actions\nOn October 21, 2016, PHMSA issued Corrective Action Order (CPF No. 3-2016-5009H),\nwhich required Magellan to shut down a 49-mile section of the anhydrous ammonia pipeline\nextending from Valley, Nebraska, (MP 223.61) to the Missouri River (MP 272.05). After repairs\nwere made, Magellan was ordered by PHMSA to operate the pipeline at a 20 percent reduction\nfrom the actual operating pressure prior to the October 17, 2016, accident.\nMagellan trains its pipeline operators annually using SCADA simulations representing\nvarious operating conditions. Following the accident, Magellan recognized that the simulation\ntraining did not fully prepare their controllers to quickly recognize and handle an ammonia release.\nMagellan developed new simulator training using the SCADA logs from the accident to train\noperators to recognize pipe breach conditions; this new training is required for the annual\ncertification of SCADA controllers.\nFollowing the accident, Magellan told the NTSB that they had re-examined the 2015 MFL\nILI data for characteristics obtained from the ruptured pipeline. Magellan technicians were able to\ndefine a new signature from the ILI data to forecast the pipeline failure. Magellan then used the\nnew ILI signature to screen the pipeline from Valley, Nebraska, to Decatur, Nebraska, where they\n7 In-Line Inspection (ILI) is an inspection of a pipeline from the interior of the pipe using an in-line inspection\ntool. It is also called intelligent or smart pigging. (NACE International Practice SP0102-2010 In-Line Inspection of\nPipelines).\n8 Magnetic Flux Leakage (MFL) testing is a nondestructive procedure for detection of corrosion and pitting in\nsteel structures. MFL is used for integrity assessment of pipelines and storage tanks.\n9 TDW Magpie Systems, Inc. MFL Sizing Accuracy Specification. Rev. B of December 2, 2005.\n10 A Spike Hydrostatic Test uses a test-pressure-to-operating-pressure ratio that significantly exceeds the minimum\nvalue of 1.25 required by federal regulation 49 CFR 195, Subpart E and the duration considerably shorter (1/2 to 1\nhour) than a minimum time of 8 hours required by this federal regulation.7\n\n<<<PAGE 8>>>\n\nAnhydrous Ammonia Release\nfound additional indications of pending failures. Magellan completed direct assessments and\nrepairs for these locations.\nIn January 2019, Magellan announced that they would decommission the 1,100-mile\nTexas to upper Midwest ammonia pipeline system later in the year. They initiated the shutdown\nand product displacement of the anhydrous ammonia pipeline system in September\n2019. According to Magellan, as of the end of December 2019, they have decommissioned\napproximately 588 miles of pipeline. Magellan indicated that they anticipate completion of the\nanhydrous ammonia displacement activities in the summer of 2020.\nProbable Cause\nThe National Transportation Safety Board determines that the probable cause of the\npipeline rupture was corrosion fatigue cracks that grew and coalesced under disbonded\npolyethylene tape coating. Contributing to the location of the cracking was external loading that\ncaused bending stress in the pipe in addition to the cyclic stresses in the pipe from the internal\npressure of the ammonia transported.\nFor more details about this accident, visit www.ntsb.gov/investigations/dms.html and\nsearch for NTSB accident identification number DCA17FP001.\nReport Date: January 29, 2020\nThe NTSB has authority to investigate and establish the facts, circumstances, and cause or\nprobable cause of a pipeline accident in which there is a fatality or substantial property damage, or\nthat involves a passenger train. (49 U.S. Code § 1131 – General authority)\nThe NTSB does not assign fault or blame for an accident or incident; rather, as specified by\nNTSB regulation, “accident/incident investigations are fact-finding proceedings with no formal\nissues and no adverse parties . . . and are not conducted for the purpose of determining the rights or\nliabilities of any person.” (49 Code of Federal Regulations, Section 831 Assignment of fault or legal\nliability is not relevant to the NTSB’s statutory mission to improve transportation safety by\ninvestigating accidents and incidents and issuing safety recommendations. In addition, statutory\nlanguage prohibits the admission into evidence or use of any part of an NTSB report related to an\naccident in a civil action for damages resulting from a matter mentioned in the report. 49 United\nStates Code, Section 1154(b).\n8","truncated":false,"body_characters":22379}