Secondary stress

Any normal or shear stress that develops as a result of material constraint. NOTE This type of stress is self-limiting, which means that local yielding can relieve the conditions that cause the stress, and single application of load will not cause failure. NOTE Definition taken from API 2RD.

Source: API RP 17L2, Recommended Practice for Flexible Pipe Ancillary Equipment, First Edition, March 2013. Global Standards


Secondary stress

Stress developed by constraint due to a geometrical discontinuity, by the use of materials of different elastic moduli under external load, by constraint due to differential thermal expansion, or by assembly load (preload) that does not impair the sealing performance of a connector. NOTE 1 Only stresses that are distributed linearly across the thickness are considered secondary stresses. For nonlinearly distributed stresses, the secondary stresses are those of the equivalent linear distribution. NOTE 2 With respect to the mechanical behaviour of the structure, the basic characteristic of secondary stresses is that they lead to plastic deformation when equalizing different local distortions in the case of excess of the yield strength. Characteristic for a secondary stress is that it is self-limiting, i.e. local flow deformation leads to a limitation of the stress. NOTE 3 Secondary stresses can be of the membrane or bending type. NOTE 4 Bending stresses caused by gross structural discontinuities and acting across the wall thickness of the pipe are classified as secondary stresses.

Source: API RP 17G, Recommended Practice for Completion/Workover Risers, Second Edition, July 2006 (Reaffirmed April 2011). Global Standards


Secondary stress

A secondary stress is any stress in the structure which is not a primary stress or peak stress.

Source: API SPEC 16R, Specification for Marine Drilling Riser Couplings, Exploration and Production Department, First Edition, January 1997. Global Standards


Secondary stress

Normal stress or a shear stress developed by the constraint of adjacent parts or by self constraint of a structure (ASME BPVC, Section VIII, Division 2, Paragraph 5.12). NOTE The basic characteristic of a secondary stress is that it is self-limiting. Local yielding and minor distortions can satisfy the conditions that cause the stress to occur and failure from one application of the stress is not to be expected.

Source: API TR 1PER15K-1, Protocol for Verification and Validation of High-pressure High-temperature Equipment, First Edition, March 2013. Global Standards

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