A325 and A490 bolts are high-strength structural fasteners commonly used in bridges and steel-framed buildings. These bolts have specific load and tension requirements as per American Society for Testing and Materials (ASTM) specifications. But what about structural steel bolt torque requirements?
At Maxpro, we’re often asked, “What is the torque required for these bolts?” This question often leads to a discussion about the difference between the required bolt load (tension) and the torque (applied force).
So, do you need torque or tension for structural bolt tightening? The answer is both—you need torque to achieve the necessary tension.
Load is the clamping force that holds the joint together, determined by the optimal design specifications of the bolt grade. Torque is the applied force that produces that load. Think of it this way: “Load is the bolt,” and “Torque is the tool applying the load.”
When testing the bolt load, use a Skidmore Wilhelm Calibore load verification stand with a calibrated torque wrench, which is available in RAD pneumatic, battery, or electric models. This tool is critical for tightening the bolts correctly and safely.
Applying the correct torque for bolts with a properly calibrated tool is critical for structural bolt tightening and maintaining a safe, efficient job site.
ISO 17025 was introduced in the 1990s and is the foremost standard for calibration labs. It ensures labs use a documented quality system to produce accurate and reliable results.
Labs and their clients agree on the services provided. Internal quality standards regulate test and calibration validity. ISO 17025 accreditation serves as proof of a lab’s competency.
When you choose a lab that calibrates according to ISO 17025, you know that they:
Additionally, ISO 17025 calibration offers peace of mind that:
Impact tools don’t provide a repeatable torque specification. They should only be used for loosening bolts, not tightening. To tighten, you’ll need a bolt-tightening torque tool.
A torque wrench will apply the repeatable torque required for the bolt to achieve the specified load. Even when using “squirt/crush” washers, we recommend using a calibrated torque wrench.
Test bolts on the Calibore daily and adjust the torque wrench based on the results. For more information, review our torque and tension specification chart, which details the minimum and maximum bolt tension and torque specifications for bolts.
Please note that this chart is only a guideline for structural bolt tightening. You should also consider factors such as changing weather, bolt lubrication, and other engineering variables.
Understanding the structural steel bolt torque requirements is essential for ensuring the safety and integrity of your construction projects. Torque is not just about tightening a bolt; it’s about applying the right amount of force to achieve the desired tension, ensuring that the structural components are securely fastened.
At Maxpro, we emphasize the importance of using the correct torque for bolts to meet the structural steel bolt torque requirements. Neglecting these requirements can lead to joint failure, compromising the entire structure.
You might also find the following document helpful for further research: Specification for Structural Joints Using ASTM A325 or A490 Bolts. This document was prepared by RCSC Committee A.1 – Specifications and approved by the Research Council on Structural Connections.
If you’d like to know more about our Calibore equipment and our extensive catalog of calibrated torque wrenches and torque tools, please contact Maxpro. We’re confident we have the right tool for your next job.
Don’t leave your project’s integrity to chance. Discover how Maxpro can provide you with the precise torque solutions you need. Contact us today to ensure your bolts are tightened correctly, safely, and in compliance with all standards.
Maxpro Corporation
427 Sargon Way, Unit D
Horsham, PA 19044
Phone: 215-293-0800 or
888-315-0175
Fax: 215-293-0803
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