This WRC bulletin addresses the issue of stud and nut structural tension capacity matching to ensure that stud fracture occurs prior to nut thread stripping. Industry standards such as ISO 10423 (API 6A) [1], ISO 13533 (API 16A) [2], and ISO 13628-4 (API 17D) [3] allow the use of low strength heavy hex nuts, i.e. ASTM A194 [4] Grade 2HM, to be applied together with high strength studs, i.e. ASTM A320 [5] Grades L43 and L7, ASTM A453 [6] Grade 660, and ASTM A193 [7] Grade B7. However, common industry practice outside ISO 10423 [1] (API 6A) is to select heavy hex nuts with similar strength and/or hardness to the studs, e.g. ASME VIII Div. 2 [8]/Div.3 [9], ISO 13628-7 [10] (API 17G), and ASTM A320 [5].In practice it has been found that the behavior of different stud/nut assemblies may vary when tightening to failure or loading to failure in service. In some cases the assemblies fail in tension through the stud threads while in other instances the threads of the nut strip. Tensile failure of the stud is easily detected. The initiation of stripping failure, though, is difficult to identify because the stripping develops gradually, some tension remains in the stud, and there is little or no visible damage. Since replacement of damaged fasteners is essential for sound and safe joints, tensile failure of the stud is required.