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Strength of casing and tubing: Difference between revisions
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Elastic Collapse is based on theoretical elastic instability failure; this criterion is independent of yield strength and applicable to thin-wall pipe (''D''/''t'' | Elastic Collapse is based on theoretical elastic instability failure; this criterion is independent of yield strength and applicable to thin-wall pipe (''D''/''t'' | ||
<nowiki>></nowiki> | <nowiki>></nowiki> | ||
25±). The minimum collapse pressure for the elastic range of collapse is calculated with '''Eq. 5'''. [[File:Vol2 page 0292 eq 003.png|RTENOTITLE]]....................( | 25±). The minimum collapse pressure for the elastic range of collapse is calculated with '''Eq. 5'''. [[File:Vol2 page 0292 eq 003.png|RTENOTITLE]]....................(5) The applicable ''D''/''t'' range for elastic collapse is shown in '''Table 4'''. <gallery widths="300px" heights="200px"> | ||
<gallery widths="300px" heights="200px"> | |||
File:Devol2 1102final Page 294 Image 0001.png|'''Table 4- D/t Range for Elastic Collapse''' | File:Devol2 1102final Page 294 Image 0001.png|'''Table 4- D/t Range for Elastic Collapse''' | ||
</gallery> | </gallery> | ||
Most oilfield tubulars experience collapse in the "plastic" and "transition" regimes. Many manufacturers market "high collapse" casing, which they claim has collapse performance properties that exceed the ratings calculated with the formulae in API ''Bull. 5C3, Formulas and Calculations for Casing, Tubing, Drillpipe, and Line Pipe Properties''.<ref name="r1">API Bull. 5C3, Bulletin for Formulas and Calculations for Casing, Tubing, Drillpipe, and Line Pipe Properties, fourth edition. 1985. Dallas: API.</ref> This improved performance is achieved principally by using better manufacturing practices and stricter quality assurance programs to reduce ovality, residual stress, and eccentricity. High collapse casing was initially developed for use in the deeper sections of high-pressure wells. The use of high collapse casing has gained wide acceptance in the industry, but its use remains controversial among some operators. Unfortunately, all manufacturers | Most oilfield tubulars experience collapse in the "plastic" and "transition" regimes. Many manufacturers market "high collapse" casing, which they claim has collapse performance properties that exceed the ratings calculated with the formulae in API ''Bull. 5C3, Formulas and Calculations for Casing, Tubing, Drillpipe, and Line Pipe Properties''.<ref name="r1">API Bull. 5C3, Bulletin for Formulas and Calculations for Casing, Tubing, Drillpipe, and Line Pipe Properties, fourth edition. 1985. Dallas: API.</ref> This improved performance is achieved principally by using better manufacturing practices and stricter quality assurance programs to reduce ovality, residual stress, and eccentricity. High collapse casing was initially developed for use in the deeper sections of high-pressure wells. The use of high collapse casing has gained wide acceptance in the industry, but its use remains controversial among some operators. Unfortunately, all manufacturers | ||
<nowiki>’</nowiki> | <nowiki>’</nowiki> | ||
claims have not been substantiated with the appropriate level of qualification testing. If high collapse casing is deemed necessary in a design, appropriate expert advice should be obtained to evaluate the manufacturer<nowiki>’</nowiki> | claims have not been substantiated with the appropriate level of qualification testing. If high collapse casing is deemed necessary in a design, appropriate expert advice should be obtained to evaluate the manufacturer<nowiki>’</nowiki> | ||
s qualification test data such as lengths to diameter ratio, testing conditions (end constraints), and the number of tests performed. | s qualification test data such as lengths to diameter ratio, testing conditions (end constraints), and the number of tests performed. | ||
=== Equivalent internal pressure === | === Equivalent internal pressure === | ||