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Bolt Testing

Skidmore Wilhelm's hydraulic tension calibrator, or bolt tension calibrator, has been the industry standard for testing high-strength bolts since we invented the technology in the 1950's. Our units are required to be used on steel buildings, bridges and other structures using fasteners in slip critical joints.

It is crucial that fabricators and erectors use our equipment to do pre-installation verification of the method to be used to install bolts. This is done by simulating the bolted joint in the Skidmore unit.

There are four approved methods for installing bolts in these structures.
  • Turn of the Nut
  • Calibrated Torque Wrench
  • Direct Tension Indicating Washers (DTIs or load indicating washer)
  • Tension Control bolts (Twist off or Lejeune bolts)

Each of these methods requires that the installer prove that the required pretension is achieved in the bolt.

Our units can safely be used with hand torque wrenches, impact guns, electric wrenches and hydraulic wrenches.