Skidmore Bolt Testing Equipment

For hex head and TC bolt testing machines, look no further than GWY. We supply Skidmore-Wilhelm and Norwolf bolt testing equipment, will assist you when performing the tests and can troubleshoot any issues that arise throughout the process.

We stock the full line of Skidmore and Norwolf bolt testing machines, as well as an extensive inventory of Skidmore and Norwolf parts and accessories.

• Wide selection of Skidmore bolt tension calibrators available for rent or sale, including these models:
  • MZ (1/2″ through 1 1/4″ bolts, 120,000 lbs maximum)
  • HS (3/4″ through 1 1/2″ bolts, 170,000 lbs maximum)
  • K (1 1/4” through 2 1/2” bolts, 225,000 lbs maximum; can be upgraded to 450,000 lbs)
• The industry’s largest inventory of bushings, plates, reaction bars and other accessories — we stock more accessories and parts than the manufacturers!

About Skidmore Bolt Testing

Skidmore first developed bolt tension calibration technology in the 1950s, and their units became the industry standard for testing high-strength bolts. In the same way that “Kleenex” became the generic term for tissues, “Skidmore” is the generic industry term used when referring to bolt tension calibrators. Today, both Skidmore-Wilhelm and Norwolf offer lines of bolt testing machines that are used for installations performed using manual, electric, pneumatic and hydraulic wrenches.

Skidmore bolt testing is required in applications such as steel buildings, bridges and similar structures. Skidmore bolt testing is performed for two main purposes:

• Preinstallation Verification (PIV) Testing, and
• Rotational Capacity (RoCap) Testing

The Skidmore Bolt Testing Process

There are two types of tests Skidmore (bolt tension calibrator) equipment is used for:

• Preinstallation Verification Testing required by AISC/RCSC, AASHTO/State DOTs
• Rotational Capacity Testing (ROCAP testing) required by ASTM F3125/AASHTO/State DOTs

Preinstallation Verification (PIV) Testing
This bolt testing process involves inserting a bolt, nut and washer assembly into the bolt tension calibrator, then tightening them just as you would in an actual steel construction. Then, a tension reading is taken from the bolt tension calibrator to verify that the minimum tension requirements for the bolt have been met. For steel buildings, the PIV test requirements, including the minimum PIV tension, are found in Section 7 of the RCSC Specification. For bridges or other structures, this information is found in the State DOT and/or project-specific specifications.

Rotational Capacity (RoCap) Testing
This bolt testing process is more involved than the PIV testing process.

1. The bolt, nut and washer assembly are inserted into the bolt tension calibrator.
2. The assembly is installed to a preliminary tension and the bolt, nut and faceplate are match-marked.
3. The assembly is then tightened to the design tension and a torque reading is taken to verify it is below the maximum torque allowed.
4. The assembly is further tightened to achieve the specified rotation from match-mark.
5. A tension reading is taken to verify that the minimum tension requirement has been met.
6. Finally, the assembly is removed from the bolt tension calibrator to verify that there are no signs of thread failure or bolt failure and that the nut can turn on the bolt to the position it was in during the test.

For steel buildings, the RoCap test requirements including all minimum and maximum torque & tension values are found in Appendix A2 of the ASTM F3125 Specification. For bridges or other structures, this information is found in the State DOT and/or project-specific specifications.

Bolt Testing Devices

There are two primary manufacturers of bolt tension calibrators (“Skidmores”); the long-time provider Skidmore-Wilhelm and the new kid on the block (although they’ve been around for over a quarter century) Norwolf. Both manufacturers produce excellent quality products that are cost competitive and offer many similar features. There are some features that set the manufacturers apart, but ultimately the choice comes down to one of personal preference and what fits the individual needs of a company or project.

For All Your Skidmore Bolt Testing Needs, Turn to GWY

Extensive Inventory
We offer the full line of Skidmore bolt testers and we stock more Skidmore parts than Skidmore.

Partnership Mindset
Since 1975, providing long-term value through customer service has been our top priority.

On-Site Repairs
We have the equipment, parts inventory and experience to service your tools and equipment.

Full-Service Expertise
Our team has the knowledge, expertise and drive to help you deliver absolute accuracy at every turn.