ABSTRACT
One point concerning which questions have been raised is the fact that the specified procedure requires testing to a level of tension 5% higher than the specified minimum pretension level. It has been argued that this does not constitute a fair and enforceable requirement because the minimum level for acceptance of the assembly by field test is 5% higher than the ASTM specified minimum proof load for A325 bolts. The argument is not valid. Rarely does the test identify bolts or nuts that do not comply with ASTM minimum requirements, but when it does, that's good: Such fasteners can be rejected before they are incorporated in the work rather than later when they are identified by postinstallation inspection. The proof load for high strength bolts is comfortably lower than the ultimate tensile strength; thus proper bolts and nuts can easily achieve loads 5% above proof load. What the test does identify is improper use of the selected installation method, mismatch of components from different sources (although each component might be within tolerance for the individual part, they may not work well together), fasteners that have become contaminated by dust or rust from improper storage, dry or improperly lubricated fasteners that need relubrication to overcome the lowering of developed tensile strength when tension is induced by tightening the nut, overtapping of nuts in the case of galvanized fasteners, and other conditions. The pretesting of fastener assemblies and installation method is the critical element in ensuring proper tension in the work. It must not be given short shrift.
