Talk to a Specialist
Want to talk to a specialist now?
(888) 838 6500
Business Hours: 8am - 5pm Est

Skidmore Bolt Testing Equipment Results Loading

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.

Trusted By:


Kind words from our customers:

  • It was a great pleasure working with GWY. They go above and beyond to help with what we needed. Don was very quick on getting what we needed out to us to complete the job. Very proud to be a GWY customer.”

  • I have enjoyed working with GWY. Their people know their product well. Their prompt response and delivery of the product is as good as any service Ogeechee Steel has ever had the pleasure of doing business with.”

  • From choosing the right equipment for each job’s unique requirements to problem solving in the field, GWY is always willing to go out of the way to find a solution. Mix that customer service in with their technical expertise and easy-to-use tools, they really help make bolt up easy.”

  • GWY’s parts inventory and response is top notch. You can expect prompt, respectful, knowledgeable answers to questions and full cooperation when you need it. Truly a mark of a reputable company with a good team.”

Get Started

For information about Skidmore rental and purchase options, parts availability or related requests, please complete this form:


Request a Quote

  • This field is for validation purposes and should be left unchanged.


Your questions, answered.

Do you bill by the month for rentals?

We typically bill by the week but we’re working on a monthly option.

Do you sell tools outside the country?

Yes, we provide tools all over the world.

Are the same size sockets interchangeable between different tools?

Typically, the answer is no but there are exceptions.  The only interchangeable sockets for current model shear wrenches are between the GV-301ZA and the GVC-301EZ. The Older models like the S-60EZA share sockets with their newer models like the S-61EZ. The same is true for the S-90EZ and GS-91EZ as well as the S-110EZ and the GS-111EZ.

There are a few TN tools that share sockets with each other such as the TN-20EZ and the TN-22EZ as well as the TN-30EZ and the TN-33EZ.

The GNR series can share sockets with some of the TN tools. The GNR-31E, 51E, & 81E can use the TN-20EZ/22EZ bar sockets instead of impact sockets. The GNR-121E can use the bar sockets of the TN-24EZA and the GNR-211E can use the bar sockets of the TN-30EZ/33EZ. The GNR’s can also share impact sockets that have their correct drive size.

Are there any used tools for sale?

We do have some used tools for sale but the selection of used is limited.

What do I do with my rental after I am done with it?

Verify everything is back in the case and send it back to GWY at 217 Forest Rd., Greenfield, NH 03047 in the preferred method of your choice.

My tips are not ejecting from the inner socket. Why?

This can happen for several reasons. It could be that your inner socket is worn and is not functioning properly. It could be a worn ejector spring or ejector pin. If you are installing galvanized bolts you may need an oversized inner socket to fix this problem. It could be that the latch and ejector system inside the tool is worn.

Is there a warranty on your tools?

1-year manufacturers defect warranty on new tools.

What is the turnaround time for repairing/recalibrating my tools?

When we receive the tools, we typically have a one to two day turnaround time before shipping back to the customer.

Buy, Rent, or Repair with GWY