{"operation":"document","citation":"PI-85-003","title":"Memo: Internal — Pipeline Safety Interpretation","source_type":"guidance","agency":"Pipeline and Hazardous Materials Safety Administration","status":"guidance","official":true,"published_on":"1985-04-12","effective_on":null,"summary":"PI-85-003 response to Memo: Internal concerning 192.195.","machine_formats":{"json":"https://regulus.evalyn.ai/document/phmsa-interpretation-pi-85-003.json","markdown":"https://regulus.evalyn.ai/document/phmsa-interpretation-pi-85-003.md"},"app_url":"https://regulus.evalyn.ai/document/phmsa-interpretation-pi-85-003","source_url":"https://www.phmsa.dot.gov/sites/phmsa.dot.gov/files/legacy/interpretations/Interpretation%20Files/Pipeline/1985/PI85003.pdf","body":"<<<PAGE 1>>>\n\nApril 12, 1985\nINFORMATION: Report on San Juan Ixhautepec, Mexico LPG Accident\nRobert L. Paullin\nAssociate Director for Operations and Enforcement, DMT-10\nL.D. Santman\nDirector, Materials Transportation Bureau, DMT-1\nAttached for your information is an additional report prepared by Mr. B.F. Olson, and an analysis\nby Jose L. de la Fuente, on the LPG accident of November 1984 that occurred near Mexico City,\nMexico. The report is copyrighted by Olson Engineering Company. It was presented to the\nUnited States Government in appreciation for the information exchange between Jose and the\nreport's author, Mr. B.F. Olson which occurred when they were in Mexico attempting to obtain\ninformation on the accident cause.\nDuring their site visits, neither Mr. Olson, nor Mr. de la Fuente were able to obtain any official\nreports other than official news releases); however, from an evaluation of information collected at\nthe site and from unofficial sources, and logical assumptions, they each have concluded that\noverpressuring of the LPG facilities from the pressure of the pipeline supplying the plant was the\nprobable cause of the accident. I agree with their conclusions.\nWe in OOE believe that an operator of a jurisdictional pipeline supplying a hazardous liquid to a\nnonjurisdiction terminal (similar to the facilities involved in this accident) is required by Part 195\nto provide pressure control and/or relief at the terminal end of the pipeline. In the past we\nfrequently have found operators with inadequate controls. This inadequacy, in most cases, has\nbeen due to the operator's lack of understanding of the regulations. Because the intrastate\noperators are not required to comply with Part 195, we anticipate that there may be many more\nintrastate pipeline-terminal facilities with inadequate controls. We will focus on this area of\nintrastate operations when we start inspecting intrastate operators, and also advise participating\nstate agencies of our emphasis. In the meantime, we are developing a recommendation to correct\nthis shortcoming in the regulations, and will submit it to DMT-30 in May 1985.\nJT\nC:\\WP51\\192\\85-04-12.N\n1\n\n<<<PAGE 2>>>\n\nMarch 21, 1985\nINFO/Analysis: Olson Engineering Company Report on San Juan Ixhuatepec, Mexico LPG\nDisaster\nJose L. de la Fuente, Asst. Chief, Southwest Region Pipeline Safety\nDr. Robert L. Paullin, Associate Director for O&E (DMT-10)\nThe report prepared by Ben Olson, postulates his belief that the LPG disaster was caused by\noverpressuring of at least one horizontal tank while being filled at the southwest corner of the\nplant. The assumptions he makes and the evidence he presents are convincing and, coupled with\nthe information I acquired, I tend to agree with Ben, that overpressuring was the probable cause\nof the disaster.\nInformation supplied to me recently by our Embassy in Mexico City and from a magazine I picked\nup while in Mexico, supports Ben's report.\nThe information supplied by our Embassy consists of press releases from the Mexican Attorney\nGeneral's Office and from Pemex. The magazine I acquired has an article on safety inspections\nperformed at the plant in September, October and on November 5, 1984, just two weeks prior to\nthe explosion.\nThe Attorney General's press release states that the explosion initiated from a sector of horizontal\ntanks located in front of the storage spheres, but lacks details.\nThe magazine article states that a safety committee inspected the plant facilities on September 17,\nOctober 5, and November 5, 1984, and found among other deficiencies, the following:\n(1) \"Relief valve on the Poza Rica - Mexico LPG pipeline receiving manifold is missing.\n(2) \"An additional relief valve is needed on the receiving manifold for the Minatitlan -\nMexico LPG pipeline now that flow has been increased to 75,000 bbl/day.\n(3) \"The pressure gauge on the receiving manifold for the Minatitlan - Mexico LPG\npipeline gives erroneous readings.\n(4) \"Approximately 25% of the pressure gauges on the horizontal tanks as well as the\nspheres are in bad shape.\"\nJT\nC:\\WP51\\192\\85-04-12.N\n2\n\n<<<PAGE 3>>>\n\nThe report concludes that, as of November 5, 1984, none of the deficiencies had been rectified.\nThis information, again, gives credence to the probability of an overpressure condition.\nThe Pemex press release on the day of the explosion is probably the most significant statement,\nalong with the ruptured horizontal tank, that lends credence to the probability of an overpressure\ncondition. The press release, as if to show the world that nothing was wrong with the Pemex\nPlant, states that pumping and flow from the pipelines supplying the LPG plant continued at a\n\"normal level\" even after the explosion occurred and was not shut down until 6:40 a.m., one hour\nafter the initial explosion.\nThe obvious questions triggered by this statement are the following:\n(1) Why wasn't the pipeline shut down immediately after the explosion?\n(2) Since it is known that the thru-put on the Minatitlan - Mexico LPG system had\nbeen increased to 75,000 bbls/day, where did the 3,125 bbls that can be pumped in one hour go?\nDid they feed the fire? Photos 29 and 30 on Page 41 show a fire which appears to be fueled.\n(3) Does the probable rapid release of a large volume of gas discharged prior to failure\nthrough the safety valves of the overpressured tank and three others which may have been being\nfilled at the same time, coupled with the high probability that pumping continued at full flow for\nan additional hour after the explosion, explain the massiveness of the spill and why no alarm or\nwarning was received by the community?\nThis scenario appears likely, based on the minimum facts gathered, but may not be conclusive.\nThere are many gaps in the report which need filling before definite conclusions can be drawn.\nHowever, paraphrasing the Attorney General's report, there exist sufficient elements to sustain a\ntechnical opinion with a reasonable degree of probability that this is what happened in San Juan\nIxhuatepec.\nThe main causal factors appear to be the human element, maintenance problems, and inadequate\nrelief capacity and pressure control. Contributing to the severity of the accident was the\nmanifolding of the tanks in each row to a common header and the probability that the outlet/inlet\nvalves to each tank were open, primarily in row #1 which is where the accident originated. As the\nfirst tank failed, the piping run also failed and this in turn started a chain reaction. Also, either due\nto damage from the initial explosion and the BLEVED* horizontal tanks, or due to\noverpressuring, the fill lines to the four 10,000 bbl spheres leaked and the gas ignited, creating\nfires which impinged on the bottom of the spheres causing them to overpressure and explode\nalmost simultaneously. Also, contributing to the severity of the accident was the failure to shut\ndown the pipeline system promptly.\nJT\nC:\\WP51\\192\\85-04-12.N\n3\n\n<<<PAGE 4>>>\n\nC: WP511192185-04-12.N\nIT\n\n<<<PAGE 5>>>\n\nPemex Press Release\nNovember 19, 1984\nThe following information is provided regarding the accident which occurred this morning in the\nTown of San Juan Ixhuatepec in the State of Mexico:\n1. In accordance with the data gathered from the accident site, the accident\noriginated outside of the Pemex installations. According to the report from the\nSub-Directorates for Primary Production and Industrial and Commercial\nTransformation, pumping to the storage and distribution plant at Ixhuatepec\ncontinued at a normal level until 6:40 a.m., including after the announcement that\nan explosion had occurred. This indicates that the operation of the plant was\nadequate.\nJT\nC:\\WP51\\192\\85-04-12.N\n5\n\n<<<PAGE 6>>>\n\nAttorney General's Office - Press Release\nDecember 22, 1984\nPage 1 - From the analysis made, it is evident that the accident which destroyed the Pemex Plant\nand directly caused major personal and property damages in San Juan Ixhuatepec, originated\nprincipally from a sector of horizontal tanks located immediately in front of the storage spheres in\nthe Pemex Plant.\nThere was a conflagration as a result of a massive escape of gas, which was presumably ignited by\na flare in the plant. There was also an explosion of tanks and other artifacts.\nPage 2 - The practically total destruction of the Pemex Plant in San Juan Ixhuatepec and the death\nof the majority of the Pemex employees on duty November 19, 1984, deprives us of certain data\nwhich would be invaluable to ascertain with greater preciseness the characteristics of the\nconflagration. However, there exist sufficient elements to sustain a technical opinion with a\nreasonable degree of probability without incurring categorical affirmations lacking due\nfoundation.\nPage 3 - Pemex provided the documentation which analyzes the ordinary maintenance problems at\nthis plant, and it is concluded that same could not by themselves have been the cause of the\noccurrence under evaluation. Said analysis forms part of a group of documents integral to this\nreport.\nThere's 4 other pages along with the original that are Spanish.\nJT\nC:\\WP51\\192\\85-04-12.N\n6","truncated":false,"body_characters":9105}