Shearing of the thread teeth along a cylinder near the root, so the fastener pulls out or spins without holding. Joints are designed so the bolt breaks in tension first, because a break is obvious while stripping is gradual and can go unnoticed during tightening. Causes include short engagement, soft or undersized nuts, oversize internal threads, overtapped nuts on plain bolts and mismatched grades.
Didn't break the bolt, stripped the nut, so either the nut's soft or that's an overtapped galv nut on a black bolt.
Also heard as
- stripped thread
- thread shear
- stripped
Related terms
Thread engagement
The axial length over which external and internal threads fully overlap, which sets stripping strength.
Nut
An internally threaded part that mates with a bolt or stud, graded so the bolt breaks before the nut strips.
Percent thread
How deep an internal thread is compared with full theoretical depth, set mainly by the tap drill size.
Overtapping
Tapping a nut oversize after galvanizing so it will fit over the thick zinc on a hot-dip galvanized bolt.
Spinner
A fastener that just turns without tightening or loosening, because its thread, insert or captive nut gave up.