{"operation":"document","citation":"PI-78-007","title":"Brown & Root, Inc. — Pipeline Safety Interpretation","source_type":"guidance","agency":"Pipeline and Hazardous Materials Safety Administration","status":"guidance","official":true,"published_on":"1978-02-22","effective_on":null,"summary":"PI-78-007 response to Brown & Root, Inc. concerning 192.619.","machine_formats":{"json":"https://regulus.evalyn.ai/document/phmsa-interpretation-pi-78-007.json","markdown":"https://regulus.evalyn.ai/document/phmsa-interpretation-pi-78-007.md"},"app_url":"https://regulus.evalyn.ai/document/phmsa-interpretation-pi-78-007","source_url":"https://www.phmsa.dot.gov/sites/phmsa.dot.gov/files/legacy/interpretations/Interpretation%20Files/Pipeline/1978/PI78007.pdf","body":"<<<PAGE 1>>>\n\nFebruary 22, 1978\nMr. Billy M. Hazlegrove\nDesign Engineer\nMarine Technology Development\nBrown & Root, Inc.\nP.O. Box 3\nHouston, Texas 77001\nDear Mr. Hazlegrove:\nWe are responding to your letter of January 30, 1978, regarding the test pressure required for a\ngas \"pipeline and riser assembly\" installed at an offshore platform.\nAs you point out, Section 192.619(a) (2) (ii) would necessitate a higher test pressure for the riser\nportion of the assembly if a single maximum allowable operating pressure (MAOP) is to be\nestablished. It would be incorrect, therefore, to test the whole assembly only to 1.25 times the\nproposed MAOP.\nYou indicate that it may be possible to conduct a preinstallation strength test on the riser portion\nof the assembly so that the pipeline portion would not have to be designed to withstand a higher\ntest pressure. If so, depending on the factual circumstances involved, such a test may be\npermissible under the provision of Section 192.505(e).\nSincerely,\nCesar DeLeon\nActing Director\nOffice of Pipeline\nSafety Operations\ndal\\192\\619\\78-02-22\n1\n\n<<<PAGE 2>>>\n\nJanuary 30, 1978\nLetter No.: B/1259\nFile No.: 4377.58\nDirector\nOffice of Pipeline Safety Operations\nDepartment of Transportation\n2100 Second Street, S.W.\nWashington, D.C. 20590\nDear Sir:\nI am presently employed in the engineering design of offshore pipelines and risers by the Marine\nTechnology Development Department of Brown & Root, Inc. Since a large part of our work\ndeals with projects in the Gulf of Mexico, we have occasions to make use of the U.S. Department\nof Transportation Pipe Line Safety Standards. A recent amendment to that code initiated this\ninquiry.\nThe area of question concerns the maximum allowable operating pressure in §192.619, paragraph\n(a) (2) (ii). According to the footnote given the requirements for this subsection were revised by\nAmendment 192-27, August 16, 1976, effective August 1, 1977. As shown in the text the\nrevision concerns the factors used to divide into the test pressure to obtain the maximum\nallowable operating pressure. Paraphrasing the revision it states that for offshore segments\ninstalled after July 31, 1977 that are not located on a platform, the factor is 1.25 and for segments\ninstalled that are located on an offshore platform, including a pipe riser, the factor is 1.5.\nThe problem arises when we have a newly installed pipeline and riser assembly going to an\nexisting platform. Normally the pipeline and riser wall thicknesses are designed based on a\nmaximum operating pressure or some similar design pressure. Then the test pressure is calculated\nby multiplying the design pressure by the factor called for in the code. Since the factor for the\nriser is 1.5 and the factor for the pipeline is 1.25, the question becomes which test pressure to use.\nIf the riser test pressure is used one has the choice of possibly overstressing the pipeline or\nredesigning the pipeline wall thickness to handle the higher riser test pressure. If the pipeline test\npressure is used the riser is not tested to code requirements.\nThis is only a problem because we have no way to test the riser and the pipeline at different\npressures in the field. Therefore is it correct to assume that the riser factor of 1.5 is only to be\nused for the pre-installed conditions? If the riser is not tested before being installed on an existing\nplatform the test pressure is assumed to be calculated by using a factor of 1.25. - 2 -\ndal\\192\\619\\78-02-22\n2\n\n<<<PAGE 3>>>\n\nThus the pipeline and riser will have the same test pressure and the riser wall thickness will have\nbeen designed to withstand only this maximum test pressure.\nConsequently, we need a clarification of what appears to be an apparent conflicting code\nrequirement.\nYour prompt consideration is greatly appreciated.\nYours very truly,\nBilly M. Hazlegrove\nDesign Engineer\nMarine Technology Development\ndal\\192\\619\\78-02-22\n3","truncated":false,"body_characters":3913}