Part of stress, which is additive to the respective primary and secondary stresses, to form the total stress. NOTE Peak stresses do not cause any noticeable distortion and are only important to fatigue and brittle fracture in conjunction with primary and secondary stresses.
Source: API RP 17G, Recommended Practice for Completion/Workover Risers, Second Edition, July 2006 (Reaffirmed April 2011). Global Standards
A peak stress is a highly localized stress that exists at a discontinuity in the load path. An example of a peak stress is the high localized stress at the root of a thread in a bolt.
Source: API SPEC 16R, Specification for Marine Drilling Riser Couplings, Exploration and Production Department, First Edition, January 1997. Global Standards