{"operation":"document","citation":"PLD21FR003","title":"Kinder Morgan, Inc. Natural Gas-Fueled Explosion and Fire","source_type":"incident","agency":"National Transportation Safety Board","status":"current","official":true,"published_on":"2023-05-09","effective_on":"2021-08-15","summary":"Accident. in Coolidge, AZ, USA. on 2021-08-15. Kinder Morgan. Rupture","machine_formats":{"json":"https://regulus.evalyn.ai/document/ntsb-case-pld21fr003.json","markdown":"https://regulus.evalyn.ai/document/ntsb-case-pld21fr003.md"},"app_url":"https://regulus.evalyn.ai/document/ntsb-case-pld21fr003","source_url":"https://www.ntsb.gov/investigations/Pages/PLD21FR003.aspx","body":"NTSB investigation PLD21FR003.\n\nEvent Type: Accident\n\nEvent Date: 2021-08-15\n\nEvent City: Coolidge\n\nEvent State Or Region: AZ\n\nEvent Country: USA\n\nPipeline Operator: Kinder Morgan\n\nPipeline Type: Gas Transmission - Regulated\n\nAccident Type: Rupture\n\nCompletion Status: Completed\n\nReport Number: PIR2301\n\nReport Date: 2023-04-27\n\nProbable cause: The National Transportation Safety Board determines that the probable cause of the August 15, 2021, pipeline rupture in Coolidge, Arizona, was tented tape wrap leading to stress corrosion cracking, a fracture at a longitudinal seam weld, and subsequent rupture of the pipe. Contributing to the rupture was Kinder Morgan’s failure to record the correct coating type used for this segment of pipeline, leading to a risk assessment that did not fully identify the risk of stress corrosion cracking.\n\nTier1Name: System operating, changing flow/pressure\n\nTier2Name: Fire/explosion (post-release)\n\nTier1Name: System operating, changing flow/pressure\n\nTier2Name: SCADA system event\n\nTier1Name: Post-release\n\nTier2Name: Emergency response\n\nTier1Name: Initiating product flow\n\nTier2Name: Product leak/release\n\nTier1Name: System operating, changing flow/pressure\n\nTier2Name: Pipe structural malfunction/failure\n\nTier1Name: System operating\n\nTier2Name: Pressure/flow/temp event\n\nFinding Tier1Name: Organizational\n\nFinding Tier2Name: Support/oversight/monitoring\n\nFinding Tier3Name: Documentation/record keeping\n\nFinding Modifier Name: Pipeline operator\n\nFinding Report Text: Organizational - Support/oversight/monitoring - Documentation/record keeping - Pipeline operator\n\nFinding Tier1Name: Organizational\n\nFinding Tier2Name: Support/oversight/monitoring\n\nFinding Tier3Name: Oversight\n\nFinding Modifier Name: Pipeline operator\n\nFinding Report Text: Organizational - Support/oversight/monitoring - Oversight - Pipeline operator\n\nFinding Tier1Name: Pipeline\n\nFinding Tier2Name: Pipeline structure\n\nFinding Tier3Name: Pipe seam\n\nFinding Modifier Name: Failure\n\nFinding Report Text: Pipeline - Pipeline structure - Pipe seam - Failure\n\nFinding Tier1Name: Pipeline\n\nFinding Tier2Name: Pipline systems/equipment\n\nFinding Tier3Name: (general)\n\nFinding Modifier Name: Failure\n\nFinding Report Text: Pipeline - Pipline systems/equipment - (general) - Failure\n\nFinding Tier1Name: Pipeline\n\nFinding Tier2Name: Pipline systems/equipment\n\nFinding Tier3Name: Coatings/anti-corrosion\n\nFinding Modifier Name: Fatigue/wear/corrosion\n\nFinding Report Text: Pipeline - Pipline systems/equipment - Coatings/anti-corrosion - 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 August 15, 2021, about 5:29 a.m. local time, a 30-inch-diameter natural gas transmission pipeline owned and operated by Kinder Morgan, Inc., ruptured in a rural area of Coolidge, Arizona. The rupture resulted in the release of natural gas vapor that ignited and exploded. The explosion and gas-fed fire destroyed a farmhouse about 451 feet away, killing two of the three occupants and seriously injuring the other.\n\nWhat We Found\nWe determined that the probable cause of the August 15, 2021, pipeline rupture in Coolidge, Arizona, was tented tape wrap leading to stress corrosion cracking, a fracture at a longitudinal seam weld, and subsequent rupture of the pipe. Contributing to the rupture was Kinder Morgan’s failure to record the correct coating type used for this segment of pipeline, leading to a risk assessment that did not fully identify the risk of stress corrosion cracking.\n\nPIR-23-01\n<<<PAGE 1>>>\n\nKinder Morgan Natural Gas–Fueled Explosion\nPIR-23/01\nIssued: April 27, 2023 Kinder Morgan\nNatural Gas–Fueled Explosion\nCoolidge, Arizona\nAugust 15, 2021\nPipeline Investigation Report: PIR-23/01\n1 Factual Information\n1.1 Accident Description\nOn August 15, 2021, about 5:29 a.m.\nlocal time, a 30-inch-diameter natural gas\ntransmission pipeline owned and operated by\nKinder Morgan, Inc., (Kinder Morgan)\nruptured in a rural area of Coolidge, Arizona.\n1\nThe rupture resulted in the release of natural\ngas vapor that ignited and exploded, causing\na blast wave and gas-fed fire.\n2 (See figure 1.)\nThe explosion and fire destroyed a farmhouse\nabout 451 feet away, killing two of the three\noccupants and seriously injuring the other. About 33 acres of vegetation were damaged\nin some areas about 878 feet away from the rupture crater. A 47-foot segment of pipe\nwas ejected about 133 feet from the center of the crater. (See figure 2.) Kinder Morgan\nestimated property damage and emergency response costs to be $5,541,740.\nFigure 1. Ruptured pipeline and fire.\n(Source: Coolidge Fire Department.)\n1 (a) Visit www.ntsb.gov to find additional information in the public docket for this NTSB accident\ninvestigation (case number PLD21FR003). Use the CAROL Query to search safety recommendations and\ninvestigations (b) All times in this report are local time unless otherwise noted.\n2 A blast wave is created when an explosion occurs and instantaneously over-pressurizes the ambient\natmospheric pressure.\n1\n\n<<<PAGE 2>>>\n\nKinder Morgan Natural Gas–Fueled Explosion\nPIR-23/01\nFigure 2. Aerial image of the accident site following the explosion and fire. (Source: Pinal County\nFire Investigation Task Force.)\nThe rupture occurred at milepost 497.07 on Line 2000.3 The location was\ndesignated a Class 1 location under Title 49 Code of Federal Regulations (CFR) 192.5\nand was not designated a high consequence area (HCA) or moderate consequence area\nunder 49 CFR 192.905 and 49 CFR 192.3, respectively.4\nPipeline operations on Line 2000 were controlled and monitored by Kinder\nMorgan’s control center in Colorado Springs, Colorado. At 5:36 a.m., about 7 minutes\nafter the rupture, Kinder Morgan personnel at the control center received 5\n3 A milepost is a unit of measure used to define the location on a pipeline relative to a chosen starting\npoint in miles and fractions of miles.\n4 (a) Class locations are defined by the population density within an onshore area that extends 220 feet\non either side of the centerline of any continuous 1-mile length of pipeline. Class 1 locations represent the\nlowest population density and Class 4 locations represent the highest population density. (b) Pipeline safety\nregulations for gas transmission pipelines define areas that have higher potential consequences to health\nand safety as high consequence areas or moderate consequence areas.\n2\n\n<<<PAGE 3>>>\n\nKinder Morgan Natural Gas–Fueled Explosion\nPIR-23/01\ninformational pressure rate-of-change alarms in 4 minutes, alerting them to a rapid drop\nin pressure in the segment of the pipeline near the rupture site.\nWorking with Kinder Morgan personnel near the rupture site, control center\npersonnel initiated emergency response activities in accordance with company\noperations and maintenance procedures at 6:02 a.m.5 To isolate the affected pipeline\nsegment, Kinder Morgan personnel needed to manually close three mainline valves\n(MLVs), MLV 37, MLV 38, and MLV 39. MLV 39, to the west of the rupture, was closed\nfirst, about 6:29 a.m. MLV 37, to the east of the rupture, was closed next, about 6:55 a.m.\nMLV 38, the valve closest to the rupture to the east, was closed about 8:16 a.m. About\n8:20 a.m., 4 minutes after MLV 38 was closed and 2 hours and 51 minutes after the\nrupture, the gas-fed fire stopped.\n1.2 Line 2000\nLine 2000 was installed in 1986 by the All American Pipeline Company for crude\noil service. The ownership of Line 2000 changed in 2000 to El Paso Natural Gas\nCompany, LLC (El Paso). In 2002 and 2003, under the ownership of El Paso, Line 2000\nwas converted from a crude oil pipeline to a natural gas transmission pipeline and its\nflow reversed from a west to east direction to an east to west direction. El Paso made\nseveral modifications to Line 2000 as part of the conversion, including the removal of a\npump station that was located about 6 miles downstream of the rupture site, relative to\nthe original crude oil flow direction of west to east.6\nOn September 6, 2002, as part of the conversion to natural gas operations and\nflow reversal, El Paso hydrostatically tested the segment of Line 2000 that ruptured in this\naccident to a pressure of 1,212 pounds per square inch, gauge (psig).\n7 This test detected\nno leaks.\nIn 2012 Kinder Morgan became the parent company of El Paso, which continued\nto operate the pipeline. Line 2000 is located within Kinder Morgan’s Western Operations\nRegion, specifically the Phoenix Area, which covers about 1,540 miles of natural gas\n5 Kinder Morgan, O&M Procedure 1900: Area/Facility Emergency Response Plan. April 1, 2020.\n6 According to a 2014 Pipeline and Hazardous Materials Safety Administration (PHMSA) advisory\nbulletin, pipeline flow reversals and conversions from crude oil to natural gas service—including removal or\nmodification of pump stations—can have system impacts related to a shift in locations along the pipeline at\nrisk for stress corrosion cracking (SCC), cyclic fatigue, or both. See PHMSA, Pipeline Safety: Guidance for\nPipeline Flow Reversals, Product Changes and Conversion to Service, September 2014.\n7 In hydrostatic testing, water is pumped into a pipeline and held at pressure to determine whether the\npipeline can withstand the pressure without leaking. The hydrostatic testing conducted at this time noted a\nleak at a nearby location, milepost 496.9. See section 1.3.2.\n3\n\n<<<PAGE 4>>>\n\nKinder Morgan Natural Gas–Fueled Explosion\nPIR-23/01\npipeline in Arizona and California. At the time of the rupture, the operating pressure of\nLine 2000 was about 863 psig, which was less than the maximum allowable operating\npressure of 944 psig.\n8 The pipeline was coated with two layers of spiral wrap tape as the\nprimary means of corrosion protection and supplemented with an impressed current\ncathodic protection system.9 Other specifications for Line 2000 are shown in table 1.\nTable 1. Line 2000 specifications\nPipeline Specification Value\nDiameter 30-inch\nMaterial Steel\nGrade1 X-70\nLongitudinal Seam Weld Double Submerged Arc-Welded\nWall Thickness 0.281 inches\nCoating Kendall Polyken Wrap Tape (two layers)\nManufacturer Bergrohr Herne or Vallourec\nCorrosion Protection Impressed Current Cathodic Protection\n1 American Petroleum Institute 5LX defines specific grades of carbon steel pipeline, each with a minimum yield strength.\nThe higher the grade of the pipeline, the higher the strength of the steel used to manufacture that pipeline.\n1.3 Integrity Management\nThe Pipeline and Hazardous Materials Safety Administration’s (PHMSA’s)\nregulations on gas transmission integrity management (IM) fall under 49 CFR Part 192\nSubpart O, Gas Transmission Pipeline Integrity Management.10 IM has three goals: (1) to\ndetermine pipeline segments where the potential consequences are the highest; (2) to\nevaluate the soundness, stability, and reliability of pipelines; and (3) to address risk in a\nscientific, consistent, and prioritized manner.\n8 Title 49 CFR 192.619, Maximum allowable operating pressure: Steel or plastic pipelines, specifies\nhow the maximum allowable operating pressure is determined.\n9 Cathodic protection is a corrosion mitigation method used by the pipeline industry to protect\nunderground steel structures. To prevent corrosion of any exposed steel, cathodic protection supplies a\nprotective electrical current through a ground bed that typically contains a string of suitable anodes, with\nsoil as an electrolyte. A wire connected to the pipeline provides the return path for the current to complete\nthe circuit.\n10 On December 15, 2003, the Research and Special Programs Administration issued its final rule on\nnatural gas transmission integrity management, setting the minimum regulatory requirements for pipelines\nin HCAs.\n4\n\n<<<PAGE 5>>>\n\nKinder Morgan Natural Gas–Fueled Explosion\nPIR-23/01\nKinder Morgan was not required to implement the IM regulations at the rupture\nlocation because the rupture site was designated a Class 1 location and was not\ndesignated as an HCA. However, before the accident, Kinder Morgan had voluntarily\nincluded the ruptured pipeline segment in their IM program as part of a nonregulatory\ninternal program.\n1.3.1 Pipeline Open Database Standard\nStarting in 2014, when Kinder Morgan field personnel exposed any segment of\nLine 2000, including excavations for defects, they completed a Pipeline Examination\nReport (PER). The data from PERs were then integrated into a Pipeline Open Database\nStandard (PODS). PODS was Kinder Morgan’s internal data management tool to identify\nand document pipeline specifications such as coating type.\n11 Data factors recorded in\nPODS were used as inputs during the risk assessments discussed in section 1.3.2.\nBetween 2014 and the day of the rupture, six PERs were completed on Line 2000\nwithin about two miles of the rupture origin; the latest PER was completed in February\n2018. In each of these PERs, which Kinder Morgan personnel then entered into PODS,\nthe coating type for the ruptured pipeline segment was listed as fusion-bonded epoxy.\nOne pipeline data report, submitted in 2011 after a composite sleeve was\ninstalled on Line 2000 approximately 375 feet from the rupture location, noted that the\ncoating type listed as fusion-bonded epoxy was incorrect at that location and that the\nactual coating type was spiral wrap tape.\n12 This was not recorded in PODS.\n1.3.2 Risk Assessment\nAt the time of the rupture, Kinder Morgan used a risk assessment to evaluate their\npipeline segments for the threats to pipeline integrity identified by the American Society\nof Mechanical Engineers (ASME) standard B31.8S.\n13 The risk assessment algorithm\ndetermined the probability of failure from stress corrosion cracking (SCC) by examining\n11 Kinder Morgan relied upon PODS to record various pipeline-specific data by location, meeting the\nrequirements of 49 CFR 192.947.\n12 This pipeline data report was a Streamline report, which was the type of report used to denote\npipeline exposures before 2014, when PERs were introduced.\n13 ASME standard B31.8S-2004, Managing System Integrity of Gas Pipelines, is incorporated by\nreference into PHMSA regulation. B.31.8S identifies nine types of threat criteria; SCC is one type of time-\ndependent threat.\n5\n\n<<<PAGE 6>>>\n\nKinder Morgan Natural Gas–Fueled Explosion\nPIR-23/01\nnear neutral and high pH SCC, the two types of SCC defined in ASME B31.8S.\n14 Kinder\nMorgan further calculated the baseline susceptibility of pipeline segments to the threat\nof SCC as the direct product of several correlating factors recorded in PODS: pipe age;\nyear of installation; pipe manufacturer and mill location; pipe diameter and wall\nthickness; downstream distance from a compressor station; location of pipe (above or\nbelow ground); soil conditions (susceptibility, pH, and resistivity); and coating type.\nBefore the rupture, the coating type of the ruptured pipeline segment was listed in\nPODS as fusion-bonded epoxy.\n15 The coating type was spiral wrap tape.\nThe Kinder Morgan risk assessment algorithm at the time of the rupture\ndetermined that near neutral SCC was an active threat to pipeline safety and integrity on\nLine 2000 at milepost 496.9, based on a 2002 hydrostatic test failure. Kinder Morgan\nrecords listed that the coating at that location was a multilayer tape system with urethane\nfoam insulation. Kinder Morgan did not identify threats of SCC on the ruptured pipeline\nsegment at milepost 497.07 where the coating type was incorrectly listed as fusion-\nbonded epoxy.\n1.3.3 Potential Impact Radius\nUnder 49 CFR 192.903, PHMSA requires operators to mathematically calculate a\npipeline’s potential impact radius (PIR), or the area where the failure of a pipeline could\nhave a significant impact on people or property when deciding whether a pipeline is in\nan HCA. Using the requirements provided by the regulations, the NTSB calculated the\npotential impact radius for the rupture site to be 636 feet. Physical evidence identified\nduring the NTSB’s onsite examination showed that damage to the surrounding\nvegetation was found up to 878 feet from the rupture crater.\n1.4 Postaccident Examinations\nNTSB investigators conducted onsite metallurgical examinations of the ruptured\npipeline on August 17–22, 2021. Examination of the pipeline just south of the fracture\n14 (a) Stress corrosion cracking is a form of environmentally assisted cracking produced under the\ncombined action of corrosion and tensile stress. SCC typically manifests as clusters of small cracks in the\nexternal body of the pipe. (b) The pH of the local environment of the pipeline surface is between 5 and 7 in\nnear neutral SCC and between 9 and 13 in high pH SCC.\n15 Fusion-bonded epoxy coating, also known as fusion-bond epoxy powder coating, is an epoxy-based\npowder coating that is widely used to protect steel pipe used in pipeline construction from corrosion.\n6\n\n<<<PAGE 7>>>\n\nKinder Morgan Natural Gas–Fueled Explosion\nPIR-23/01\nnoted that the undamaged pipe was covered in an adhesive coating followed by two\nlayers of plastic spiral wrap tape.16\nThe ejected pipe segment was cut into several pieces, which were sent to the\nNTSB Materials Laboratory in Washington, D.C., for testing. The laboratory examination\nof these pieces found the pipeline fracture was caused by SCC that originated on the\noutside surface of the pipe, predominantly along the edge, or toe, of the longitudinal\nseam weld. (See figure 3.)\nFigure 3. Ejected pipe segment just after the rupture.\nThe NTSB’s examination of the ejected pipe segment observed colonies of\nlongitudinal surface breaking cracks that had propagated through the wall as\nintergranular cracking consistent with high pH SCC.17 The maximum depth of the SCC\npresent in the ejected pipe segment was about 0.14 inches—approximately 50 percent of\nthe nominal wall thickness. (See figure 4.) The origin of the fracture contained three SCC\nregions with a combined length of about 3.1 feet, whose ends were connected by a\n16 NTSB investigators observed that most of the coating of the ejected pipe segment had been\nconsumed by fire, leaving most of the external surface bare.\n17 Intergranular cracking is the propagation of cracks along the grain boundaries of a polycrystalline\nmetal or alloy.\n7\n\n<<<PAGE 8>>>\n\nKinder Morgan Natural Gas–Fueled Explosion\nPIR-23/01\ntransverse overstress crack.18 The longitudinal cracks had coalesced and formed a crack\nat the rupture site large enough to split open the pipeline.\nFigure 4. Cross section of ejected pipe segment.\nEvidence of pitting corrosion was observed on the outer surface of the pipe at the\ntoe of the longitudinal seam weld, consistent with disbonded coating from tented tape\nwrap that had shielded the toe of the weld from cathodic protection.\n19\n1.5 Postaccident Actions\n18 (a) Details of the fracture examination can be found in the NTSB Materials Laboratory Factual Report\nNo. 21-003, March 7, 2022, in the docket for this accident. (b) A transverse crack is a circumferentially\noriented crack extending around the pipe, usually perpendicular to its length. (c) An overstress crack occurs\nwhen the strength of a material is exceeded; this crack can extend through the thickness of the material.\n19 (a) Disbonded coating is when pipeline coating separates from the metal of the pipe, causing a gap\nbetween coating and pipe surface. (b) Tented tape wrap, or tenting, is a form of disbonded coating that can\noccur at longitudinal seams. Tenting causes a gap between the coating and where the weld meets the pipe\nsurface. (c) Tape coating can shield the cathodic protection current from reaching the exposed pipe wall,\nallowing corrosion to form on the external pipe surface.\n8\n\n<<<PAGE 9>>>\n\nKinder Morgan Natural Gas–Fueled Explosion\nPIR-23/01\n1.5.1 Pipeline and Hazardous Materials Safety Administration\nOn August 19, 2021, PHMSA issued a corrective action order to Kinder Morgan\nregarding the August 15 rupture.\n20 The corrective action order required El Paso to\nisolate, or shut down, the 38.6-mile segment of Line 2000 from MLV 37 to MLV 39; to\nreduce the operating pressure of Line 2000; to conduct a leakage survey and to review\nprior in-line inspections on Line 2000; to verify the records that established the maximum\nallowable operating pressure for Line 2000; and to develop a plan, approved by\nPHMSA, to resume operation of the isolated pipeline segment.\n21\n1.5.2 Kinder Morgan\nKinder Morgan corrected the Line 2000 coating data that were placed in PODS.\nKinder Morgan created a new procedure for all its natural gas transmission and\ngathering pipelines that, in cases when a PER field observation shows coating type\ninconsistent with PODS data, requires the PODS data team to compare the original\nsource documentation with the PER and to make the necessary corrections in PODS.\nAfter completing a review of PODS and PER data for Line 2000, Kinder Morgan\nconducted a new risk assessment for Line 2000.\nOn December 19, 2021, Kinder Morgan conducted electromagnetic acoustic\ntransducer testing on the segment of Line 2000 that ruptured. This testing resulted in\nexcavations to four areas; upon examination of these areas, Kinder Morgan found one\narea of SCC. By June 25, 2022, Kinder Morgan had completed about 19 miles of spike\nhydrostatic testing on Line 2000, including at the rupture site, to validate the results from\nthe electromagnetic acoustic transducer testing. Three hydrostatic test failures were\nobserved, none of which were within 500 feet of the rupture site. The pipe sections that\nexperienced hydrostatic test failures were cut out and sent to a metallurgical laboratory\nto determine the failure mechanism; results did not indicate the presence of SCC. These\npipe sections were replaced and retested successfully.\n2 Analysis\n20 (a) The corrective action order (CPF No. 2-2021-012-CAO) was issued to Kinder Morgan as the\nparent company of El Paso. (b) PHMSA enforcement actions include corrective action orders that are issued\nwhen a pipeline facility is or would be hazardous to life, property, or the environment, and specifies\ncorrective measures that must be taken under the authority of 49 U.S.C. 60112.\n21 In-line inspection is an inspection method in which a highly specialized tool is passed within a\npipeline to inspect the pipeline from the inside. In-line inspection uses nondestructive examination\ntechniques to identify, locate, and size various damages and defects, depending on the type of tool.\n9\n\n<<<PAGE 10>>>\n\nKinder Morgan Natural Gas–Fueled Explosion\nPIR-23/01\nIn this accident, a Kinder Morgan natural gas pipeline ruptured in rural Coolidge,\nArizona, destroying a nearby farmhouse and killing two of its three occupants. A\nsegment of the pipe was ejected in the rupture.\nNTSB investigators conducted metallurgical testing of the ejected pipe segment\nand found longitudinal surface breaking cracks, evidence of high pH SCC, in three\nregions at the toe of the ejected pipe segment’s longitudinal seam weld. Pitting\ncorrosion observed on the surface of the tested pipe pieces indicated that moisture had\nsettled on the pipe surface, likely due to tenting of the spiral wrap tape coating at the\ngap between the coating and where the weld meets the pipe surface. The tape coating\nhad most likely shielded the toe of the weld from cathodic protection, allowing the toe of\nthe weld to corrode from SCC. Over time, the three SCC regions had spread, eventually\nconnecting into one larger fracture, which split open the pipeline on August 15, 2021.\nKinder Morgan had voluntarily included the segment of Line 2000 that ruptured\nin its integrity management program and subsequently conducted risk assessments on\nthe accident segment. However, the data on coating type on the accident pipeline\nsegment, recorded in PODs and used in Kinder Morgan’s risk assessment algorithm, was\nincorrectly listed as fusion-bonded epoxy rather than as spiral wrap tape. The coating\ntype data for the accident pipeline segment remained incorrect despite at least one\ninstance of information gathering that documented the error.\nDifferent pipeline coating types offer different levels of protection from SCC.\nSpiral wrap tape coating is known by the pipeline industry to be more vulnerable than\nother coating types to SCC. Had the coating data in PODS been correctly listed as spiral\nwrap tape coating, as it was at milepost 496.9, the threat of SCC could likely have been\nidentified. However, Kinder Morgan’s IM program did not identify the threat of SCC at\nthe rupture location and thus did not address it.\nAs a result of this accident, Kinder Morgan corrected their records in PODS. They\nalso tested the section of Line 2000 that ruptured and replaced several areas of pipe.\nPHMSA issued a corrective action order to Kinder Morgan to shut down the affected\npipeline segment, reduce the operating pressure of the pipeline, and develop a plan for\nreopening the segment.\nFederal regulations require operators to mathematically calculate a pipeline’s PIR,\nthe area where a pipeline’s potential failure could have a significant impact on people or\nproperty. The NTSB calculated the PIR for the rupture site to be 636 feet; however,\nphysical evidence identified during the NTSB’s onsite examination showed that damage\nto the surrounding vegetation was found up to 878 feet from the rupture crater. Such\ndiscrepancies between the calculated PIR and evidence collected at accident scenes\nhas been seen before and prompted the NTSB to further evaluate the assumptions\non which the PIR equation is based during the investigation of a pipeline rupture in\n10\n\n<<<PAGE 11>>>\n\nKinder Morgan Natural Gas–Fueled Explosion\nPIR-23/01\nDanville, Kentucky. On August 15, 2022, NTSB Recommendation P-22-1 was issued to\nPHMSA: “Revise the calculation methodology used in your regulations to determine the\npotential impact radius of a pipeline rupture based on the accident data and human\nresponse data discussed in this report.”22 The recommendation is classified “Open—\nAcceptable Response.”\n3 Probable Cause\nThe National Transportation Safety Board determines that the probable cause of\nthe August 15, 2021, pipeline rupture in Coolidge, Arizona, was tented tape wrap\nleading to stress corrosion cracking, a fracture at a longitudinal seam weld, and\nsubsequent rupture of the pipe. Contributing to the rupture was Kinder Morgan’s failure\nto record the correct coating type used for this segment of pipeline, leading to a risk\nassessment that did not fully identify the risk of stress corrosion cracking.\nThe National Transportation Safety Board (NTSB) is an independent federal agency charged by\nCongress with investigating every civil aviation accident in the United States and significant events in other\nmodes of transportation—railroad, transit, highway, marine, pipeline, and commercial space. We determine\nthe probable cause of the accidents and events we investigate and issue safety recommendations aimed at\npreventing future occurrences. We also conduct safety research studies and offer information and other\nassistance to family members and survivors for any accident investigated by the agency. Additionally, we\nserve as the appellate authority for enforcement actions involving aviation and mariner certificates issued by\nthe Federal Aviation Administration (FAA) and US Coast Guard, and we adjudicate appeals of civil penalty\nactions taken by the FAA.\nThe NTSB does not assign fault or blame for an accident or incident; rather, as specified by NTSB\nregulation, “accident/incident investigations are fact-finding proceedings with no formal issues and no\nadverse parties … and are not conducted for the purpose of determining the rights or liabilities of any\nperson” (Title 49 Code of Federal Regulations section 831.4). Assignment of fault or legal liability is not\nrelevant to the NTSB’s statutory mission to improve transportation safety by investigating accidents and\nincidents and issuing safety recommendations. In addition, statutory language prohibits the admission into\nevidence or use of any part of an NTSB report related to an accident in a civil action for damages resulting\nfrom a matter mentioned in the report (Title 49 United States Code section 1154(b)).\nFor more detailed background information on this report, visit the NTSB investigations website and\nsearch for NTSB accident ID PLD21FR003. Recent publications are available in their entirety on the NTSB\nwebsite. Other information about available publications also may be obtained from the website or by\ncontacting—\nNational Transportation Safety Board\nRecords Management Division, CIO-40\n490 L’Enfant Plaza, SW\nWashington, DC 20594\n(800) 877-6799 or (202) 314-6551\n22 See Pipeline Investigation Report NTSB/PIR-22/02, Enbridge Inc. Natural Gas Transmission Pipeline\nRupture and Fire, Danville, Kentucky, August 1, 2019.\n11","truncated":false,"body_characters":28912}