Canadian Contractor

All About Fasteners: Episode 8: How ITW tests its fasteners, Part 2 (VIDEO)



Andrea Galindo, technical specialist with ITW, demonstrates a pull test on a 3/8" x 4" RSS GRK screw installed in wood

In this video, Andrea Galindo, a technical specialist with GRK, shows Rob Koci another type of test that the firm does at its Toronto test facility.

This piece of equipment measures the force required to pull a fastener out of wood (and different species of wood).

In this case a GRK 3/8″ x 4″ RSS screw, which has a Canadian standard of 800 to 1,000 lbs of tension before it fails, requires 2,588 lbs of pulling to rip it out of the wood assembly. Again, this demonstrates the margin of safety that GRK builds into its fasteners (as do all reputable manufacturers) versus the rated allowable forces.


Forces for the pulling (tensile) strength of fasteners – and fastener assemblies- are measured in pounds. The British testing machine that Andrea is using here measures forces in kilonewtons (kN). One kilonewton is equal to approximately 225 pounds. If you can remember that conversion factor three minutes after watching the video, you have too much time on your hands!


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