{"operation":"document","citation":"PI-74-0141","title":"California Public Utilities Commission — Pipeline Safety Interpretation","source_type":"guidance","agency":"Pipeline and Hazardous Materials Safety Administration","status":"guidance","official":true,"published_on":"1974-10-18","effective_on":null,"summary":"PI-74-0141 response to California Public Utilities Commission concerning 192.507.","machine_formats":{"json":"https://regulus.evalyn.ai/document/phmsa-interpretation-pi-74-0141.json","markdown":"https://regulus.evalyn.ai/document/phmsa-interpretation-pi-74-0141.md"},"app_url":"https://regulus.evalyn.ai/document/phmsa-interpretation-pi-74-0141","source_url":"https://www.phmsa.dot.gov/sites/phmsa.dot.gov/files/legacy/interpretations/Interpretation%20Files/Pipeline/1974/g74-10-18_Johnson_192.507-msfx.pdf","body":"<<<PAGE 1>>>\n\nPI-74-0141\nOctober 18, 1974\nMr. William R. Johnson, Secretary\nCalifornia Public Utilities Commission\nCalifornia State Building\nSan Francisco, CA 94102\nDear Mr. Johnson:\nThis refers to you letter of August 2, 1974, requesting interpretations of three subjects under 49 CFR Part 192.\nFirst, with respect to isolating a test segment from an adjacent segment under section 192.557(b)(5), you ask if the\nadjacent segment must be cut and capped or may a regulator be used to isolate the test segment. Any means may be\nused to provide the required t isolation under section 192.557(b)(5), including the use of a regulator.\nSecondly, you ask what type of pressure test must be performed under section 192.619(a)(2)(ii) in uprating to the level\npermitted by that section. Section 192.619(a)(2)(ii) does not specify the type of pressure test required. Therefore, any\nnormally accepted means for leak or strength testing, such as the ones you mention, will suffice.\nFinally, with respect to an interpretation published in Advisory Bulletin No.74-7 involving uprating steel pipe to a\npressure which produces a hoop stress less than 30 percent of SMYS, you ask why it was stated that a \"strength\" test\nmust be performed under section 192.619(a)(2)(ii). In this interpretation, the nature of the test required by section\n192,619(a)(2)(ii) was not at issue and not relevant to the decision therein. The term \"strength test\" was used in a broad\nsense to refer to the test requirements of section 192.619(a)(2)(ii) without intending to suggest that particular criteria is\ninvolved. We recognize, however, that to the extent the terms \"strength test\" and \"leak test\" connote different types\nof pressure tests in the mind of the gas industry, the use of \"strength test\" in the published interpretation was an\noverstatement of the requirement.\nWe appreciate your concern for the correctness and clarity of the Federal gas pipeline safety standards and the\npublished interpretations. We anticipate that future rule making actions by this office will eliminate possible confusion\nin the areas you have discussed.\nSincerely\nJoseph C. Caldwell, Director\nOffice of Pipeline Safety\n\n<<<PAGE 2>>>\n\nAugust 2, 1974\nMr. Joseph C. Caldwell, Director\nOffice of Pipeline Safety\nDepartment of Transportation\nWashington, D. C. 20590\nDear Mr. Caldwell:\nThis is in reply to your first letter of May 6, 1974, which constitutes your response to our letter of April 9, 1974,\nconcerning your oral interpretation of 49 CFR 192.557(b)(5), and also in reply to your second letter of May 6, 1974,\nDocket Number CA-74-2, by which you stayed this Commission's Resolution No.G-1627. The resolution granted the\nPacific Gas and Electric Company a waiver of compliance with Section 192.557(b)(5) of 49 C.F.R.\nThe commission takes no exception to the staying of its Resolution No. G-1627. However, after analyzing your reasons\nfor objecting to the granting of this waiver, the Commission's engineering staff sees there are areas of possible\nconfusion which it believes should be clarified. One of these relates to the isolation required by Section 192.557(b)(5),\none is in regard to the pressure test referred to in your letters, and one has to do with the proper application of Section\n192.619(a), to situations involving uprating under Section 192.557. These are discussed in turn below.\nISOLATION\nHere there may be confusion arising from our respective interpretations or definitions of the concept of isolation as\nused in Section 192.557(b)(5). In granting the waiver, we interpreted that section as requiring complete isolation ( e.g.\nby cutting and capping any end connections to the segment under test). This would, of course, interrupt service to any\ncustomers receiving gas from that segment, and this was the kind of isolation which we were waiving. Under such\nwaiver, both we and the utility company understood that during the test the segment would be \"isolated\" from the rest\nof the system by means of the very regulators which would later be used in operating the rest of the system at lower\npressures. It we further understood that the uprating procedure would utilize a leak survey and would be performed in\naccordance with 192.557(c) and 192.553(a), and that it would be carried out while the segment was under draft, albeit\nat a time when the draft was at a minimum.\nIt now occurs to us that your definition of isolation might be based on the use of regulators to keep the higher pressure\nin the test segment from the various lines connected to the test segment. Given this definition, we would certainly\nagree that such isolation cannot and must not be waived. It was not the intent of our resolution to waive this type of\nisolation.\nHowever, if your objection to our resolution is an objection to the waiving of complete and absolute isolation, then we\nwould have difficulty in understanding such an objection. If, after successfully going through the steps called for in\n192.577(c) and 192.553(a), the segment is going to be operated at the same pressure as that achieved during the\nuprating under those sections, it is certainly going to be operated with regulators on every connecting line operating at\nlower pressure, and therefore those same regulators could have been used, with perfect safety, during the uprating\nprocedure.\nWe would very much appreciate being advised of your definition of isolation as it is required by Section 192.557(b)(5).\nPRESSURE TEST\nYou state in your second letter that \"a pressure test is required when operating pressure is increased under Section\n192.557 to a maximum level permitted by Section 192.619(a)(2)(ii).\" We would like to know on which of the following\ndefinitions of pressure test the statement just quoted is based:\n1. The term \"pressure test\" can mean a strength test in which a certain test pressure is maintained in a\n\n<<<PAGE 3>>>\n\nsealed pipe system for some specified time period, No draft of the test medium from the system is\nallowed. To pass the test, the pipe must not develop any rupture. Failure is indicated by a radical drop\nin pressure.\n2. The term \"pressure test can mean a form of leak test in which a system is pumped up to a certain test\npressure, the system is sealed and the pressure source disconnected, and the pressure is observed for\nsome specified time period. Existence of a leak is indicated by a continuing drop in pressure. Location\nof leak must be determined by observation or survey. No draft of the test medium from the system is\nallowed.\n3. The term \"pressure test\" can mean a form of leak test in which the system is not sealed. Pressure is\nincreased up to a certain test pressure and maintained at that level, with the pressure source left\nconnected to the system. Both existence and location of leak are determined by observation or survey.\nDraft of the test medium from the system is allowed to the extent that the pressure source is able to\nmaintain the test pressure.\nAPPLICATION OF SECTION 192.619(a)\nYou state in your first letter: \"For a steel pipeline operated at 100 psig or more, in uprating under Section 192.557 to a\npressure permitted by Section 192.619(a)(2)(ii), a pressure test must be performed under that section.\"\nWe are having difficulty in understanding the basis for that statement. It is true that Section 192.619(a)(2)(ii) refers to\n\"the pressure to which the segment was tested after construction\" and to \"the test pressure.\" However, the section\ndoes not seem to specify that this test pressure must be that pressure which was attained during a pressure or strength\ntest. The section would seem equally to refer to the pressure attained during a leak test. We would appreciate very\nmuch your clarifying this point.\nIn further reference to the application of Section 192.619(a), you state in your Advisory Bulletin No. 74-7, in regard to\nsteel pipelines operating at 100 psig or more and with hoop stresses less than 30% SMYS: \"In uprating to a pressure\npermitted by Section 192.619(a)(2)(ii), a strength test must be performed. The increments prescribed by Section\n192.557(c) apply to the increase in pressure between the existing MAOP and the test pressure or the desired MAOP\nmultiplied by the appropriate factor in Section 192.619(a)(2)(ii).\" This is apparently a further elucidation of the\ninterpretation you gave of this section in your letters to this Commission.\nWe find ourselves at variance with this view, in that we have always understood Section 192.557 specifically to exclude\nfrom the restrictions of Section 192.619(a) any steel pipeline being uprated to a pressure which would produce hoop\nstresses less than 30% SMYS.\nThere are three grounds for this inference. First, it would seem reasonable to expect a safety order not to require a\nstrength test, at 1.4 times desired operating pressure, for uprating pipe having a yield strength which is 3.3 times the\nhoop stress at the desired operating pressure.\nSecond, such expectation is completely fulfilled when one reads in Section 192.555(c), for pipe to be operated over 30%\nSMYS, \"After complying with paragraph (b) of this section, an operator may increase the maximum allowable operating\npressure of a segment of pipeline constructed before September 12, 1970, to the highest pressure that is permitted\nunder Section 192.619 . . . \"(emphasis added), and then one reads in Section 192.557(c), for pipe to be operated under\n30% SMYS, \"After complying with paragraph (b) of this section, the increase in maximum allowable operating pressure\nmust be made in increments that are equal to 1- psig or 25 percent of the total pressure increase, whichever produces\nthe fewer number of increments.\" (Emphasis added.) Note that there is, in Section 192.557(c), no reference to Section\n192.619, as there is in Section 192.555(c). Instead, Section 192.557(c) calls for incremental pressure increases, and this\nimmediately directs one back to the requirements of Section 192.553(a) which is couched in terms of leak tests and leak\nsurveys, not in terms of strength tests.\n\n<<<PAGE 4>>>\n\nAnd third, this same intent (i.e., of not requiring a strength test for pipelines to be operated at less than 30% SMYS) is\nevident in the USA Standard Code for Pressure Piping, Gas Transmission and Distribution Piping Systems, USAS B31.8 -\n1968, from which Subpart K is derived. Section 845.34 of this Standard applied to high-pressure distribution mains, and\nto pipelines, operated with hoop stresses less than 30% SMYS. Paragraph (a) of Section 845.34 allowed the MAOP to be\nincreased to a level not greater than that allowed under Section 845.33, the only applicable portion of which referred to\nthe design pressure of the weakest element of the system. Such increase in MAOP did not require a strength test, but\ninstead called for requirements similar to those of Sections 192.557(b) and (c) in 49 C.F.R.\nIn further support of our position, it should be pointed out that, for certain pipelines, and under your recent\ninterpretation of the applicability of Section 192.619(a), the uprating requirements for old lines (Section 192.557) are\nmore stringent than the test requirements for new lines to be operated under identical conditions (Section 192.507).\nIn closing, we would like to state that, in our opinion, your recent interpretation of the applicability of Section\n192.619(a) to the uprating requirements of Section 192.557 makes an impact on the original intent of these safety\norders of much magnitude that it is, in effect, rule making; as such, it should be accorded the usual privileges of public\nexamination. review, and criticism.\nThis Commission would appreciate receiving your comments on it views as stated above.\nVery truly yours,\nPUBLIC UTILITIES COMMISSION\nWilliam R. Johnson, Secretary\n\n<<<PAGE 5>>>\n\nMay 6, 1974\nMr. William R. Johnson, Secretary\nCalifornia Public Utilities Commission\nCalifornia State Building\nSan Francisco, CA 94102\nDear Mr. Johnson:\nThank you for your letter of April 9, 1974, commenting on an oral interpretation by Office of Pipeline Safety staff\nconcerning 49 CFR 192.557(b)(5) as it pertains to steel pipelines operated at a hoop stress of less than 30 percent of\nSMYS. As you state, this section requires that before a segment of pipeline is uprated it must be isolated from any\nadjacent segment that will continue to be operated at a lower pressure. According to your letter, our interpretation was\nthat section 192.557(b)(5) also requires testing for leaks for a period of at least 1 hour, and it is your understanding that\nthe test may be accomplished by leak survey.\nSubject to the requirements of section 192.621 or section 192.623, as the case may be, the maximum allowable\noperating pressure for a pipeline may not be increased above the lowest pressure determined under section 192.619(a).\nFor a steel pipeline operated at 100 psig or more, in uprating under section 192.557 to a pressure permitted by section\n192.619(a)(2)(ii), a pressure test must be performed under that section. Steel pipelines operated at less than 100 psig\nmay be uprated under section 192.557 to a pressure permitted by section 192.619(a) without conducting a pressure\ntest. Where a pressure test is performed in uprating under section 192.557, the standards do not specify the nature of\nthe test. However, the provisions of section 192.507, applicable to tests on new or replaced or relocated pipe, can serve\nas a guide. Under this section, a test pressure must be held for 1 hour. In spite of this interpretation, the Commission\nmay wish to consider waiving the pressure test requirement in appropriate circumstances as permitted by section 3(e)\nof the Natural Gas Pipeline Safety Act of 1968.\nIn conjunction with uprating, section 192.553(a)(1) requires incremental pressure increases to be held while the pipeline\nis checked for leaks. This leak check may be performed by survey, and there is no minimum time specified for holding\nthe pressure.\nWe trust this interpretation corrects any misunderstanding you may have. We are always happy to answer any requests\nfor interpretations. We prefer, however, that requests be made in writing to avoid possible misunderstanding by both\nparties involved.\nSincerely,\nSigned: De Leon\nJoseph C. Caldwell\nDirector\nOffice of Pipeline Safety\n\n<<<PAGE 6>>>\n\nPublic Utilities Commission\nState of California\nApril 9, 1974\nOffice of Pipeline Safety\nDepartment of Transportation\n400 Seventh Street, SW\nWashington, D.C. 2C590\nGentlemen:\nThe Commission is concerned with a ruling received from your people on the interpretation of Section 192.557 (b)(5) of\nour General Order No. 112-C. Telephonically your staff has indicated this requires that the section of pipeline to be up\nrated has to be completely isolated and tested for leaks for a period of at least one hour. This interpretation is not in\naccord with the strict wording of this section. The requirement for isolation from. . .” any adjacent segment that will be\ncontinued to be operated at a lower pressure” is simply a necessary requirement to raising the pressure in the line to be\nuprated and is not part of the uprating test procedure.\nCertain lines falling into the classification of producing a hoop stress less than 30% of SMYS are feeder mains that cannot\nbe taken out of service for such testing without shutting down a large number of customers. Since these lines are\noperating at less than 30% of SMYS the interpretation that has been provided is unduly restrictive and may place an\nunnecessary hardship on the customers of the gas system.\nOur staff has interpreted Section 192.557, with respect to the testing procedure for transmission lines, that such up\nrating should be done at a time of minimum pressure gradient and that the leak test may be done by leak survey.\nThe Commission believes that no modification to the requirements is necessary; however, the interpretation being\nmade of these requirements should be corrected to reflect good operating practice.\nVery truly yours,\nPublic utilities Commission\nWilliam R. Johnson, Secretary","truncated":false,"body_characters":16011}