Strain-to-first crack

The weep point or strain-to-first-crack in a wall for filament-wound pipe constructed using isophthalic plastic is currently found to be not less than 0.009 in./in. This has been repeatedly demonstrated by careful coupon testing and burst testing of pipes with strain gauge instrumentation attached. 

Thus, design values are based on the strain-to-first-crack or the empirical weep point. For normal design conditions a strain of 0.0018 in./in. is used, which provides a five-to-one safety factor. For transient design conditions a strain of 0.0030 in./in. is used, for a safety factor of approximately three to one. To those familiar with the design safety fac-... 

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See also in sourсe #XX -- [ ]

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