Mastering Bolt Installation: Pre-Installation Verification Explained

Using the correct structural bolt installation method plays a critical role in ensuring utmost safety and reliability of steel structures. Different types of projects require specific bolt installation techniques tailored to their unique materials, loads and regulatory requirements.

To meet safety standards and achieve optimal results, it’s essential to select the right installation method. The most common techniques include:

• Turn-of-Nut: After being snug tightened, the bolt is tightened to a specified rotation to ensure proper tension without requiring direct tension measurement.
• Calibrated wrench: A torque wrench is set to a predetermined value and applies the correct tension to the bolt.
• Tension control (TC): This method utilizes a TC bolt with a splined end that shears off when the correct tension is reached.
• Direct tension indicator (DTI): This method requires a washer with raised protrusions that flatten under the correct load to provide a visual indication of proper tension.
• Combined method: DTIs are used with the Turn-of-Nut method for added visual confirmation.

Each of these methods is intended to achieve precision and accuracy during installation, which is confirmed through PIV. Proper PIV ensures that all materials, tools and methods are appropriate for the project at hand and meet the highest industry standards before any work begins.

Pre-installation verification is the process of confirming that all components, tools and methods used in installation are properly aligned and compliant with industry standards before work begins. The goal of PIV is to prevent errors that could compromise the safety and structural integrity of a project. Construction teams must perform PIV on three bolts from every lot to minimize the risks associated with improper bolt installation, which could lead to injury or costly rework.

If a bolt, nut or washer fails during PIV, installation cannot proceed with that lot. Instead, the installer must determine the cause, whether it’s a material defect, tool calibration issue or incorrect procedure, and correct it before retesting. This safeguard ensures only compliant bolts are used in the final structure, protecting both safety and project timelines.

PIV helps prevent issues such as:

• Under-tightened bolts
• Incorrectly sized fasteners
• Tool malfunctions
• Incorrect installation methods

PIV is guided by several important industry standards, including the Research Council on Structural Connections (RCSC) and the American Institute of Steel Construction (AISC), which provide the framework for ensuring that structural connections are safe and reliable.

• Research Council on Structural Connections: The RCSC publishes the Specification for Structural Joints Using High-Strength Bolts, which outlines the necessary requirements for bolt installation, including the methods of installation and the steps for pre-installation verification.
• American Institute of Steel Construction: AISC provides guidelines for the design, fabrication and erection of structural steel. Their Steel Construction Manual establishes proper installation techniques and stresses the importance of pre-installation verification in ensuring the safety and proper performance of steel structures.

By adhering to these standards, construction teams can ensure compliance with national safety regulations and guarantee that their installations meet the highest quality benchmarks.

Implementing PIV requires more than just a quick check of tools and materials. Once the installation method is chosen, ironworkers must conduct PIV on three bolts from every lot before installation even begins. Here’s an overview of how PIV is typically carried out on the job site:

1. Confirm materials and tools: Verify that bolts, nuts, washers and tools meet project specifications and are in good working condition.
2. Inspect for defects: Conduct a visual check of all fasteners and tools to ensure they’re clean, defect-free and ready for use.
3. Validate tool settings: Confirm that torque wrenches and tension tools are properly calibrated and set to the correct values.
4. Perform tension checks: Use appropriate tools to ensure bolts achieve the required tension before installation begins.
5. Document the process: Keep accurate records of all PIV checks to support compliance, quality assurance and future reference.

If any components change during the project, another PIV test must be conducted to confirm that the selected installation method still meets the required performance standards.

While this overview highlights the essentials, the full PIV process involves specific tools, techniques and documentation practices tailored to your chosen installation method. For a more detailed, step-by-step guide, including tool recommendations and inspection criteria, download our complete eBook Pre-Installation Verification: All Install Methods.

Even when teams use quality bolts and the right tools, a variety of issues can disrupt the process, leading to delays and costly rework or even compromise structural integrity.

Some of the most common challenges include:

• Improper tightening: Both under- and over-tightening can weaken connections and shorten a structure’s lifespan.
• Skipping the snug-tight step: Failing to properly snug bolts before final tightening leads to inaccurate tensioning.
• Incorrect fasteners: Using the wrong size, grade or type of bolt can cause serious strength and performance issues.
• Environmental factors: Temperature swings, poor storage conditions or contaminated fasteners can all affect installation quality.
• Tool-related issues: Power supply problems, worn brushes or the wrong cord setup can cause electric tools to perform inconsistently.
• Human error: Mistakes caused by insufficient training or oversight remain one of the biggest risks on any job site.

Fortunately, most of these challenges can be avoided through PIV. The process helps identify and correct problems before installation begins, ensuring tools, materials and techniques are ready to perform as intended.

To take it a step further, best practices such as thorough planning, proper training and regular tool calibration add another layer of protection. Teams that document procedures, refresh training and maintain calibration schedules are far less likely to face costly setbacks.

Have questions about PIV? With decades of experience in structural bolting, GWY provides the knowledge, tools and support you need to get the job done right the first time. From sales and rentals to calibration and repair, GWY is a trusted partner for every stage of bolt installation. Give us a call or send us a message with any questions.

How is PIV different from bolt inspection during installation?
PIV happens before any bolts are installed in the structure. It confirms that the fasteners, tools and chosen installation method are capable of achieving the required tension under project conditions. By contrast, bolt inspection during installation takes place after bolts have been installed, verifying that each connection meets specifications. Both are required by standards such as RCSC and AISC, but PIV is what gives installers and inspectors confidence that installation will proceed smoothly and without costly rework.

Can PIV be skipped if tools are already calibrated?
No. Even when torque wrenches or shear wrenches are properly calibrated, PIV is still required. Calibration confirms that the tool can deliver accurate results, but PIV goes further by verifying the complete system under actual job site conditions. Standards such as the RCSC Specification make this clear: three bolts from every lot must be tested with the tools intended for installation. Skipping PIV introduces risk, since even minor variations in fasteners, power supply or site conditions can affect performance. Calibration and PIV work together, but one cannot replace the other.