{"operation":"document","citation":"PI-20-0006","title":"AC Engineering LLC — Pipeline Safety Interpretation","source_type":"guidance","agency":"Pipeline and Hazardous Materials Safety Administration","status":"guidance","official":true,"published_on":"2020-06-24","effective_on":null,"summary":"PI-20-0006 response to AC Engineering LLC concerning 192.195, 192.197.","machine_formats":{"json":"https://regulus.evalyn.ai/document/phmsa-interpretation-pi-20-0006.json","markdown":"https://regulus.evalyn.ai/document/phmsa-interpretation-pi-20-0006.md"},"app_url":"https://regulus.evalyn.ai/document/phmsa-interpretation-pi-20-0006","source_url":"https://www.phmsa.dot.gov/sites/phmsa.dot.gov/files/docs/standards-rulemaking/pipeline/interpretations/74126/ac-engineering-llc-pi-20-0006-06-23-2020-part192-195-and-192-197.pdf","body":"<<<PAGE 1>>>\n\nU.S. Department\nof Transportation\nPipeline and Hazardous\nMaterials Safety Administration June 24, 2020\n1200 New Jersey Avenue, SE\nWashington, DC 20590\nMr. Marc S. Young\nAC Engineering LLC\nPO Box 1693\nSealy, TX 77474\nDear Mr. Young:\nIn a letter to the Pipeline and Hazardous Materials Safety Administration (PHMSA), dated\nFebruary 10, 2020, you requested an interpretation of 49 Code of Federal Regulations (CFR) Part\n192. Specifically, you requested an interpretation of §§ 192.195 and 192.197 as they relate to\noverpressure protection of a specific natural gas pipeline system.\nIn your capacity as a licensed professional engineer who has dealings with regulated\nmunicipalities and local distribution companies, you requested an interpretation of these\nregulations as they apply to a specific system where the normal operating pressure from a\ndelivering pipeline is in the range of 250 pounds per square inch gauge (psig) (1,724 kPa gage)\nto a city gate inlet. You provided a drawing of the system to supplement your request for\ninterpretation. You stated you are concerned because it appears some designers are selecting to\neliminate relief valves or shutoff valves by assuming two regulators are sufficient overpressure\nprotection devices without complying with all of the Part 192 overpressure protection\nrequirements. You provided five statements and questions and asked PHMSA to respond to each\none. PHMSA’s responses follow your statements, which have been reproduced below:\nQuestion 1: Confirm that if there is no high pressure distribution system (i.e. the custody transfer\nfrom the shipping pipeline at the inlet of a municipal gas utility or local distribution company’s\ncity gate) then the piping from the custody transfer receipt point and any manifold which handles\none or more service lines to the city gate regulator, or regulators and a manual bypass line, if so\npiped, to the downstream flange of the first regulator or isolation valve is considered a high\npressure distribution system for the purposes of the 49 CFR 192.197.\nAnswer: Section 192.3 defines a high-pressure distribution system as a distribution system in\nwhich the gas pressure in the main is higher than the pressure provided to the customer.\nTherefore, what you described meets the definition of a high pressure distribution system if the\ndelivery pipeline is in the range of 250 psig as you indicated.\nQuestion 2: If the normal operating pressure at the inlet to the 1st regulator is above 60 psig (414\nkPa gage), then subpart (a) and (b) of 49 CFR 192.197 are not applicable and subpart (c) of 49\nCFR 192.197 is applicable.\nThe Pipeline and Hazardous Materials Safety Administration, Office of Pipeline Safety provides written clarifications of the Regulations (49 CFR\nParts 190-199) in the form of interpretation letters. These letters reflect the agency's current application of the regulations to the specific facts\npresented by the person requesting the clarification. Interpretations are not generally applicable, do not create legally-enforceable rights or\nobligations, and are provided to help the specific requestor understand how to comply with the regulations.\n\n<<<PAGE 2>>>\n\n2\nAnswer: Section 192.197(c) is applicable for a distribution system that exceeds a maximum\nactual operating pressure of 60 psig.\nQuestion 3: If the normal operating pressure at the inlet to the first regulator is above 125 psig\n(828 kPa gage), then 49 CFR 192.197(c)(1) or (2) must be used.\nAnswer: Section 192.197(c)(3) may not be used where the inlet pressure on the service regulator\nexceeds 125 psig (862 kPa gage). For higher inlet pressures, the methods in § 192.197(c)(1) or\n(2) must be used. Also, a service regulator and an automatic shutoff device that closes upon a\nrise in pressure downstream from the regulator and remains closed until it is manually reset can\nbe used per § 192.197(c)(4).\nQuestion 4: Confirm if either: a) the prescribed method in 49 CFR 192.197(c)(1) - an upstream\nregulating valve with a downstream regulating service valve that either operate a relief valve or a\nshutoff valve to prevent overpressure, or b) 49 CFR 192.197(c)(2) - a series of a primary\nregulator and a monitoring regulators, either alone or in parallel, and the piping contains a\nmanual bypass line around the regulated service lines, even if locked closed and only utilized for\nlimited periods during repair and maintenance, that a relief valve or quick acting shutoff is not\nmandatory to prevent overpressure of the downstream low pressure distribution system as\nrequired to satisfy 49 CFR 192.195. While it is not included in this regulation by reference, I\nwould suggest that the caveats given in API Standard 521/ISO 232512 run counter to the\nsuggestion of just applying a locking mechanism and to use administrative controls, e.g. to just\ninstruct personnel to keep the bypass locked during normal operations. Does the Office of\nPipeline Safety’s Interpretation of 49 CFR 192.199 remain the same as it was almost 21 years\nago?\nAnswer: With regard to overpressure protection for a manual bypass pipeline, there is a\nrequirement for safety lock under § 192.199(h) that applies to gas pipeline valves installed\nbetween the system to be protected and relieving or limiting device. However, per §§ 192.619(b)\nand 192.621(b), no person may operate a segment of pipeline unless overpressure protective\ndevices are installed on the segment in a manner that will prevent the maximum allowable\noperating pressure from being exceeded, in accordance with § 192.195. As for API\nStandard 521, PHMSA does not interpret this standard because it is not incorporated into the\nFederal pipeline safety regulations.\nThe rule in § 192.199(h) protects against unauthorized operation of a valve used for overpressure\nprotection such as a valve in by-pass piping. The operator is required by § 192.605 to have\ndetailed operating and maintenance procedures that are implemented by properly qualified\noperator personnel when valves in by-pass piping are being used for overpressure protection. By\n\"operator personnel\" we mean persons employed by an operator or working for a contractor\nengaged by an operator, including subcontractors and qualified in accordance with Part 192,\nSubpart N.\nThe Pipeline and Hazardous Materials Safety Administration, Office of Pipeline Safety provides written clarifications of the Regulations (49 CFR\nParts 190-199) in the form of interpretation letters. These letters reflect the agency's current application of the regulations to the specific facts\npresented by the person requesting the clarification. Interpretations are not generally applicable, do not create legally-enforceable rights or\nobligations, and are provided to help the specific requestor understand how to comply with the regulations.\n\n<<<PAGE 3>>>\n\nQuestion 5: Does 49 CFR 192.199 or 192.201 mandate a relief to protect a low-pressure\ndistribution system, particularly if the system is to transition to polyethylene pipe, even if\n49 CFR 192.197(c)(1) or (2) is employed upstream either with or without a manual bypass.\nAnswer: If piping meets §§ 192.197(a) and (b) or (c)(1) or (2), the maximum relief pressures\nmust not exceed the maximum pressure limits in §§ 192.201 or 192.739, as applicable. Whether\nthere is a steel to plastic pipeline connection or not, under § 192.619(a), no person may operate a\nsegment of steel or plastic pipeline at a pressure that exceeds a maximum allowable operating\npressure determined by the weakest element in the segment. Therefore, an operator with steel to\nplastic connection must design and operate its pipeline in accordance with Part 192 requirements.\nIf we can be of further assistance, please contact Tewabe Asebe at 202-366-5523.\nSincerely,\nJohn A. Gale\nDirector, Office of Standards\nand Rulemaking\nThe Pipeline and Hazardous Materials Safety Administration, Office of Pipeline Safety provides written clarifications of the Regulations (49 CFR\nParts 190-199) in the form of interpretation letters. These letters reflect the agency's current application of the regulations to the specific facts\npresented by the person requesting the clarification. Interpretations are not generally applicable, do not create legally-enforceable rights or\nobligations, and are provided to help the specific requestor understand how to comply with the regulations.\n\n<<<PAGE 4>>>\n\nFebruary 10, 2020\nUS DOT Office of Pipeline Safety\nPipeline and Hazardous Materials Safety Administration (PHMSA)\nU.S. Department of Transportation\n1200 New Jersey Avenue, SE\nWashington, DC 20590-0001\nSubject: Request for Interpretation of 49 CFR 192.195 and 49 CFR 192.197\nDear Sir or Madam,\nAs a licensed professional engineer who has dealings with regulated municipalities and Local\nDistribution Companies from time to time, I am formally requesting an interpretation of 49 CFR 192. 195\nentitled “ Protection against accidental overpressuring” and 49 CFR 192.197 entitled \"Control of the\npressure of gas delivered from high-pressure distribution systems.\", with respect to subpart (c) where\nthe normal operating pressure from a delivering pipeline is in the range of 250 p.s.i. (1,724 kPa) gage to\nthe city gate inlet.\n49 CFR 192.195 states:\n(a) General requirements. Except as provided in § 192.197, each pipeline that is connected to a gas\nsource so that the maximum allowable operating pressure could be exceeded as the result of pressure\ncontrol failure or of some other type of failure, must have pressure relieving or pressure limiting devices\nthat meet the requirements of §§ 192.199 and 192.201.\n(b) Additional requirements for distribution systems. Each distribution system that is supplied from a\nsource of gas that is at a higher pressure than the maximum allowable operating pressure for the system\nmust -\n(1) Have pressure regulation devices capable of meeting the pressure, load, and other service conditions\nthat will be experienced in normal operation of the system, and that could be activated in the event of\nfailure of some portion of the system; and\n(2) Be designed so as to prevent accidental overpressuring.\nand\n49 CFR 192.197 states:\n“(a) If the maximum actual operating pressure of the distribution system is 60 p.s.i. (414 kPa) gage, or\nless and a service regulator having the following characteristics is used, no other pressure limiting device\nis required:\n(1) A regulator capable of reducing distribution line pressure to pressures recommended for\nhousehold appliances.\n(2) A single port valve with proper orifice for the maximum gas pressure at the regulator inlet.\n\n<<<PAGE 5>>>\n\n(3) A valve seat made of resilient material designed to withstand abrasion of the gas, impurities\nin gas, cutting by the valve, and to resist permanent deformation when it is pressed against the\nvalve port.\n(4) Pipe connections to the regulator not exceeding 2 inches (51 millimeters) in diameter.\n(5) A regulator that, under normal operating conditions, is able to regulate the downstream\npressure within the necessary limits of accuracy and to limit the build-up of pressure under no-\nflow conditions to prevent a pressure that would cause the unsafe operation of any connected\nand properly adjusted gas utilization equipment.\n(6) A self-contained service regulator with no external static or control lines.”\n“(b) If the maximum actual operating pressure of the distribution system is 60 p.s.i. (414 kPa) gage, or\nless, and a service regulator that does not have all of the characteristics listed in paragraph (a) of this\nsection is used, or if the gas contains materials that seriously interfere with the operation of service\nregulators, there must be suitable protective devices to prevent unsafe overpressuring of the customer's\nappliances if the service regulator fails.”\n“(c) If the maximum actual operating pressure of the distribution system exceeds 60 p.s.i. (414 kPa)\ngage, one of the following methods must be used to regulate and limit, to the maximum safe value, the\npressure of gas delivered to the customer:\n(1) A service regulator having the characteristics listed in paragraph (a) of this section, and\nanother regulator located upstream from the service regulator. The upstream regulator may not\nbe set to maintain a pressure higher than 60 p.s.i. (414 kPa) gage. A device must be installed\nbetween the upstream regulator and the service regulator to limit the pressure on the inlet of the\nservice regulator to 60 p.s.i. (414 kPa) gage or less in case the upstream regulator fails to\nfunction properly. This device may be either a relief valve or an automatic shutoff that shuts, if\nthe pressure on the inlet of the service regulator exceeds the set pressure (60 p.s.i. (414 kPa)\ngage or less), and remains closed until manually reset.\n(2) A service regulator and a monitoring regulator set to limit, to a maximum safe value, the\npressure of the gas delivered to the customer.\n(3) A service regulator with a relief valve vented to the outside atmosphere, with the relief valve\nset to open so that the pressure of gas going to the customer does not exceed a maximum safe\nvalue. The relief valve may either be built into the service regulator or it may be a separate unit\ninstalled downstream from the service regulator. This combination may be used alone only in\nthose cases where the inlet pressure on the service regulator does not exceed the manufacturer's\nsafe working pressure rating of the service regulator, and may not be used where the inlet\npressure on the service regulator exceeds 125 p.s.i. (862 kPa) gage. For higher inlet pressures,\nthe methods in paragraph (c) (1) or (2) of this section must be used. (emphasis added)\n(4) A service regulator and an automatic shutoff device that closes upon a rise in pressure\ndownstream from the regulator and remains closed until manually reset.”\n\n<<<PAGE 6>>>\n\nMy specific request is for an interpretation of these regulations with respect to the following questions:\n1. 2. 3. 4. Confirm that if there is no H.P. Distribution system (i.e. the custody transfer from the shipping\npipeline at the inlet of a Municipal Gas Utility or LDC’s City Gate) then the piping from the\ncustody transfer receipt point and any manifold which handles one or more service lines to the\ncity gate regulator, or regulators and a manual bypass line, if so piped, to the downstream\nflange of the 1st regulator or isolation valve is considered a H.P. Distribution system for the\npurposes of the 49 CFR 192.197.\nIf the normal operating pressure at the inlet to the 1st Regulator is above 60 p.s.i. (414 kPa) gage,\nthen subpart (a) and (b) of 49 CFR 192.197are not applicable and subpart (c) of 49 CFR 1192.197\nis applicable.\nIf the normal operating pressure at the inlet to the 1st Regulator is above 125 p.s.i. (828 kPa)\ngage, then 49 CFR 192.197 c (1) or (2) must be used.\nConfirm if either a) the prescribed method in 49 CFR 192.197 c (1) { an upstream regulating\nvalve with a downstream regulating service valve that either operate a relief valve or a shutoff\nvalve to prevent overpressure} or b) 49 CFR 192.197 c (2) {a series of a Primary Regulator and a\nMonitoring Regulators), either alone or in parallel, and the piping contains a manual bypass line\naround the regulated service lines, even if locked closed and only utilized for limited periods\nduring repair and maintenance, that a relief valve or quick acting shutoff is NOT mandatory to\nprevent overpressure of the downstream low pressure distribution system as required to satisfy\n49CFR192.195.1 While it is not included in this regulation by reference, I would suggest that the\ncaveats given in API Standard 521 / ISO 232512 run counter to the suggestion of just applying a\nlocking mechanism and to use administrative controls, e.g. to just instruct personnel to keep the\n1 This appears to be the interpretation of 49 CFR 192.199 given by George Tenley, Jr., Director of Office of Pipeline\nSafety in Interpretation PI-90-007 to Charles Heath of Heath and Associates on 2-22-1999. I would disagree with\nMr. Tenley’s assessment of the purpose of the regulations being only to protect against accidental overpresssure\ncaused by failure of piping components. The regulations, incorporate ASME B31.8 by reference. In Section 845\nCONTROL AND LIMITING OF GAS PRESSURE; 845.1 Basic Requirement for Protection Against Accidental\nOverpressuring; “Every pipeline, main, distribution system, customer’s meter and connected facilities, compressor\nstation, pipetype holder, bottle-type holder, containers fabricated from pipe and fittings, and all special equipment,\nif connected to a compressor or to a gas source where the failure of pressure control or other causes might result\nin a pressure that would exceed the maximum allowable operating pressure of the facility (refer to para. 805.2.1),\nshall be equipped with suitable pressure-relieving or pressure-limiting devices. Special provisions for service\nregulators are set forth in para. 845.2.7.” Comment: It would seem a logical conclusion that the bypass service\nline does not qualify for the regulator exceptions set forth in 845.2.7, since it only has a single block valve or in\nthe case of a double block and bleed, two block valves and a vent valve, between the high pressure source and\nthe lower pressure rated distribution mains.\n2 “The potential for the bypass valve to be inadvertently opened while the control valve is operating should also be\nconsidered unless administrative controls are in place. If the pressure resulting from the opening of the bypass\nvalve can exceed the corrected hydrotest pressure (see 3.21 and 4.3.2), reliance on administrative controls as the\nsole means to prevent overpressure might not be appropriate. The user is cautioned that some systems can have\nunacceptable risk due to failure of administrative controls and resulting consequences due to loss of containment.\nIn these cases, limiting the overpressure to the normally allowable overpressure can be more appropriate. Note\nthat the entire system, including all of the auxiliary devices (e.g. gasketed joints, instrumentation), should be\nconsidered for the overpressure during the failure of administrative controls.” Excerpt from API Standard 521 / ISO\n23251, Section 5.10.3.\n\n<<<PAGE 7>>>\n\n5. bypass locked during normal operations.3 Does the Office Of Pipeline Safety’s Interpretation of\n49 CFR 192.199 remain the same as it was almost 21 years ago?\nDoes 49 CFR 192.199 or 192.201 mandate a relief to protect the a low pressure distribution\nsystem, particularly if the system is to transition to polyethylene pipe, even if 49 CFR 192.197 c\n(1) or (2) is employed upstream either with or without a manual bypass.\nIncluded in this request is a isometric drawing that was submitted for a bid and was signed and sealed\nby a professional engineer that made no representation that it was preliminary. It has only a single\nisolation valve on the bypass between the upstream source and although there is a second 600# valve, a\ndownstream valve to an odorizer takeoff is rated at only 285 psig (ANSI 150).\nIt is my judgement as a licensed engineer who has performed many flare and relief studies on gas plants\nand offshore oil & gas facilities, as well as constructed and operated interstate and intrastate pipes that\nthe design shown is flawed. The reason is simply that an erroneous operation of the valve or a failure to\nbe able to reclose it once open, due to line debris, could result in a loss of containment in the polypipe\nsection. This is proposed to be placed in the right of way of a major interstate highway. Shouldn’t the\nregulations require this design to have a relief valve or a slam shut valve to protect the steel to polypipe\ntransition listed on the right end based on the requirements of the above referenced 49 CFR 192.195, 49\nCFR 192.197 and 49 CFR 192.199?\n3 It is also possible to put the gas system at very high risk for loss of containment, if operating company personnel\ntry to operate their City Gate systems by throttling the bypass while repairs are made to a plugged or faulted set of\nregulators. Particularly if there is not some sort of filtration, upstream of the regulators and the dead space in the\nbypass line were to filled with a partial blockage. A person simply may not be able to respond quick enough to a\nchange in demand, if the service customers are few with a few high demand intermittent services, the LP\ndistribution system is small and there is a high differential pressure between the supplying pipeline and the LP\nDistribution Headers or if a valve once set had a partial blockage move. As noted in the reported incident cited in\nthe 1999 interpretation, experience has shown this can lead to loss of containment.\n\n<<<PAGE 8>>>\n\nMy reason for requesting an interpretation is my concern for the fact that there appear to be some\ndesigners selecting to eliminate relief valves or shutoff valves by just assuming two regulators are\nsufficient overpressure protection without complying with all the stated requirements.\nMarc S. Young, PE\nAC Engineering LLC (F-17852)\nPO Box 1693\nSealy, Texas 77474","truncated":false,"body_characters":21073}