BS ISO 18953:2025

This document specifies test methods to determine loss of pretension in high-strength bolts due to the presence of coatings on the faying surface(s) of a bolted joint to be used in structural steelwork, when any of the coatings are thick enough to affect the pretension in a bolt in the short term, or can show significant deformation over time under sustained loads (creep-prone materials).

The presence within the grip of the bolt of other materials having considerably smaller stiffness than steel, such as insulation, is not included in this test method.