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• <br />BACKGROUND <br />Some previous work on vibration impacts on transmission pipelines <br />exists. An examination of earttrquake-induced pipeline responses concluded <br />that buried pipelines move with ilre ground and nut differentially. The most <br />serious concern was for locations a+lrere the soil-rock characteristics abruptly <br />change (Ref. 1). The Corps of Enyineers conducted a test of pipeline <br />responses to a concentrated 10-ton blast (Ref. 2). One end of a 6-in <br />diameter, 220-ft long, pressurized pipeline was located only 79 ft from ground <br />zero. Despite that end being in the crater and ejects zone and experiencing <br />some permanent displacement, no visible breaks occurred. Internal pressure <br />Irad dropped from 500 to 400 psi, but no leaks coulrJ be seen. Peak dynamic <br />strains, all measured lonyitudinally, were ]100-1400 µin/in and estimated <br />total strains, including those from pr-essurizalion, would be about 1550. The <br />autfrors of the Corps' report estimated yield stresses and strains of 60,000 <br />lb/inz and 2,000 µin/in, respectively, and reported measured radial vibration <br />of 168 in/s. <br />The most extensive studies of blastiny and pipelines were conducted by <br />the Southwest Research Institute (SwRI} fur the Pipeline Ilesearclr Committee <br />(FRC) of the American Gas Association (Ref. 3-5). Their concerns were of both <br />mining and close-in construction blasting with small charges. In their <br />initial studies, they examined vibration propagation in soil and developed <br />equations and nonroyrapfrs predictiny stresses from pipeline characteristics, <br />distances and charye weights. These tests were done both at laboratory scale <br />an on two operating mainline systems of 24- and 30-irr diameter. Even thouylr <br />the pipelines 4+e re full size, stand-off distances and charye weiyhts were <br />small, beirry 6-13 fl and 5-]5 lbs/delay fur tire 24-in pipeline and 9-15 ft and <br />3-5 lbs for the 30-in. Such small distances were placing the pipelines close <br />or possibly within the permanent or plastic yround strain zones. <br />The Enron Gas Pipeline Group developed a standard based on this SwRI <br />research (Ref. 6). Tlrey applied the prediction equations with maximum dynamic <br />stress criteria of 1000 lb/inz for arc-welded and 500 lb/inz for acetylerre- <br />welded or mechanically jointed pipelines. A follow-up study by So-rRl for PRC <br />examined blastiny in rock (Ref. 5). Again concern was for small clraryes, up <br />to 20 lbs/delay. 1easured strains were .less than those from the previously <br />found for the experiments in soil. Strains were very low except for a few <br />measurements made so close as to likely be in tfre inelastic deFormation zone <br />(as close as 16 blast-hole diameters). Altlrouglr the autfrors of this report <br />are unsure how comparable the previous SwRI studies are to full-scale mining <br />blasts, they anticipate some comparisons in the more comprehensive report to <br />follow. <br />Dowding's text (Ref. 7) includes prediction equations for pilreline <br />stresses and strains showing worst cases fur low propagation media. They <br />address strains from bending and stretchiny and stresses based on ground <br />displacements. <br />u <br />• <br />131 <br />