The ultimate load a fastener carries in straight tension, usually expressed as a minimum stress in ksi or MPa. Because the threaded section is weaker than the shank, the stress is figured over the tensile stress area, which for inch threads is 0.7854 times the square of (diameter minus 0.9743 divided by TPI). A 1/2-13 bolt has a stress area of about 0.142 square inches, so a Grade 8 at 150 ksi breaks at roughly 21,300 lb.
Minimum tensile strength on a half-thirteen Grade 8 is about twenty-one thousand pounds, so that hoist ring is your weak link, not the bolt.
Also heard as
- ultimate tensile strength
- UTS
Related terms
Proof load
The tensile load a full-size fastener must hold without measurable permanent stretch, about 90 percent of yield.
SAE grade
The inch bolt strength system, chiefly Grades 2, 5 and 8, identified by radial lines on the head.
Property class
The metric strength grade of a bolt or nut, stamped on the head as a number such as 8.8, 10.9 or 12.9.
Preload
The tension created in a bolt by tightening it, which clamps the joint and keeps it from slipping or opening.