Can I tighten A325 and A490 structural bolts by turning the head of the bolt?
Yes. Per the RCSC Specification for Structural Joints Using High-Strength Bolts (2014), section 8.2, it says:
“When it is impractical to turn the nut, pretensioning by turning the bolt head is permitted while the rotation of the nut is prevented, provided that the washer requirements in Section 6.2 are met”
When tightening bolted joints fasteners using SAE Gr. 8 bolts, washers (ASTM F436) and Grade 8 lock nuts with nylon inserts, is there a significant difference in tightening torque when holding the nut or bolt head? Thanks.
@Robert – All things being equal, the torques should not be significantly different. If there is additional friction on one surface or another, that could make a difference, but if not, the torques should be about the same.