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• Corps of Engineers conducted a
<br /> • test of pipeline responses to a
<br /> concentrated 10-ton blast (Ref. Sheet Dreams
<br /> 2). One end of a 6-in diameter,
<br /> • 220-ft long, pressurized pipeline
<br /> was located only 79 ft from ;--:,:A.. ;. �ground zero. Despite that the
<br /> end being in the crater and ejecta • ; =u, ;''
<br /> zone and experiencing some per- ,a,�" ''
<br /> manent displacement, no visible
<br /> breaks occurred. Internal pres- �,. ;. ...
<br /> sure had dropped from 5(X) to _ - u;, , .
<br /> 400 psi, but no leaks could be , ., '� ,:
<br /> seen. Peak dynamic strains, all • .r• .. /'- •:., • _ :.3k
<br /> ,.Y •measured longitudinally, were •r-?w !"` _.; ,.
<br /> 1100-1400 pin/in and estimated .. _ •° •.y;, •
<br /> total strains,including those from .
<br /> pressurization, would be about ' +" ;�`
<br /> 1550. The authors of the Corps' ':== :
<br /> report estimated yield stresses 2'y .,
<br /> and strains of 60,000 lb/in`and �':r •�` r•2,000 pin/in, respectively, and / � '
<br /> reported measured radial vihra- ±4„ , •" _°' ;�, "°# •'•; •• '•
<br /> lion of 168 in/s. f - < ;j
<br /> The most extensive studies of .
<br /> blasting and pipelines were con- 1 \"I 'le • , .:.: ,. • 'r f
<br /> ducted by the Southwest Research .• ' J :. '.
<br /> Institute (SwRI) for the Pipeline •`- '
<br /> Research Committee(PRC)of the ' '.
<br /> American Gas Association (Ref. 1,,,-,..:.:.:.1, ..:.!: . y.,` , :'• '., 'a
<br /> te '�'
<br /> 3-5). Their concerns were of ,. .- >:, �.�.-;,.
<br /> both mining and close-in con- i.-:., X't,;,
<br /> 'ir. -
<br /> struction blasting with small , • '( t
<br /> charges. In their initial' studies, ;' '
<br /> �b M
<br /> they examined vibration propaga- . • .
<br /> Lion in soil and developed equa-
<br /> dons and nomographs predicting Alton a long day,you've earned a good night's sleep. You'll sloop well knowing
<br /> stresses from pipeline characteris- tket Nobel Insurance Company's claims management staff is ready to respond to
<br /> tics, distances and charge weights. emergencies day or night Call our Marketing Department today for information
<br /> These tests were done both at lab- our our liability insurance program.and the agent nearest you.
<br /> oratory scale and on two operat-
<br /> ing mainline systems of 24- and NOBEL INSURANCE COMPANY
<br /> 30-in diameter. Even though the (800) 766- 6235
<br /> pipelines were full size, stand-off
<br /> distances and charge weights
<br /> were small, being 6-13 ft and •
<br /> 5-15 lbs/delay for the 24-1n pipelines. A follow-up study by He the previous SwR1 studies are
<br /> pipeline and 9-15 ft and 3-5 lbs SwRI for PRC examined blasting to full-scale mining blasts, they
<br /> for the 30-in. Such small distances in rock (Ref. 5). Again concern anticipate some comparisons in
<br /> were plating the pipelines close was for small charges, up to 20 the more comprehensive report
<br /> or possibly within the permanent lbs/delay. Measured strains were to follow.
<br /> or plastic ground strain zones. less than those from the previous. Dowding's text (Ref. 7)
<br /> The Enron Gas Pipeline Group ly found for the experiments in includes prediction equations for
<br /> developed a standard based on soil. Strains were very low pipeline stresses and strains
<br /> this SwRI research (Ref. 6) They except for a few measurements showing worst cases for low
<br /> applied the prediction equations made so close as to likely be in the propagation media. They address
<br /> with maximum dynamic stress cri- inelastic deformation zone as strains from bending and stretch-
<br /> teria of 1000 Ib/in'for arc-welded close as 16 blast-hole diameters). ing and stresses based on ground
<br /> and 500 lb/in'for acetylene-weld- Although the authors of this displacements.
<br /> ed or mechanically jointed report are unsure how corn para. (continued on page 34)
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