Methods of determining the stress-strain state and fracture toughness of gas- and oil-line pipe (survey)

Conclusion We have surveyed the existing methods of determining the stress-strain state and fracture toughness of gas and oil lines. The discussion illustrated the promise of methods of evaluating the stress-strain state that are based on allowance for the strain-hardening of the material of the pipe or plastic indicators attached to its surface and deformed along with it. The first method, being destructive, can be used to evaluate the effect of different shaping methods on the strength of the pipe material, to analyze accidental pipeline fractures, and to generate a data bank on the stress-strain state of sections of a pipeline that have lost their longitudinal stability and are scheduled for replacement. Information obtained from the first method can also be used to establish correlations between the geometric parameters of such sections (deflection, curvature) and their stress-strain state. This will make it possible, with the use of reliable statistical methods, to predict the stress level on curved sections of pipelines without having to cut out samples for testing and analysis. Translated from Prikladnaya Mekhanika, Vol. 33, No. 8, pp. 3–30, August, 1997.