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Resistance And Strength Through Galvanized TC Bolts

Galvanized TC bolts are construction fasteners that include an added level of resistance. Also called tension control bolts or twist-off bolts, they are used to connect steel parts in many structural applications.

TC bolts consist of a partially threaded bolt, which ends in a part called a spline. They may have a round or hex-shaped head. They are also paired with a washer and a nut as part of a total assembly. Preliminary lubrication is applied to the assembly, which is required for the unique installation process of these bolts.

TC bolts are placed into a hole or connection so the head of the bolt rests against one side of the material. The washer rests against the other with the nut behind it. A tool called a TC gun or a shear wrench is used to torque the nut and the spline of the bolt simultaneously and in opposite directions. When the assembly is properly tightened to an optimal level of tension, the spline will break off and the nut and bolt will be secured. The process to complete this is fast, thorough, and can be completed by just one person.

TC bolts may be made from various types of steel. Galvanization is only applied to those that are made from carbon steel, medium carbon alloy steel, and those that fall under ASTM’s A325 or F1852 specs. The galvanization of these parts is completed through a hot-dipped galvanization process or through electroplating. This is done to improve the corrosion resistance of these bolts through a zinc-based coating. The addition is effective for mitigating the potential for rust, oxidation, and other types of degradation and is a more cost-effective alternative to using stainless steel fasteners.

Per certain specifications set by the American Society for Testing and Material organization, not all TC bolt types can be conventionally galvanized. Those made from alloy steel and meant for use in heavy-duty or high-strength settings cannot be conventionally galvanized, as doing so poses the risk of hydrogen embrittlement. TC bolts that cannot be galvanized but still require corrosion resistance treatments can be coated with zinc or aluminum to gain comparable levels of resistance.

Galvanized TC bolts are a standard in applications where some moisture, salt, or chemical exposure can be anticipated. Galvanization will provide a level of protection against oxidation that’s comparable to stainless steel. It is still very important that galvanized TC bolts be used within recommended temperature ranges. For TC bolts, this range is between 40 and 90 degrees Fahrenheit (4 to 32 degrees Celsius).

When galvanized TC bolts are required, they should only be sourced from a reputable fastener distributor or manufacturer that can provide all appropriate quality and testing certifications. Integrity confirmations should always be obtained since these fasteners are used to serve such a vital function.

Can TC Bolts Be Galvanized?

Certain types of TC bolts can be galvanized while others cannot. This is based on their industrial spec, which accounts for potential conflict with the materials from which they are made and their intended applications. Most commonly, ASTM A325/F1852 TC bolts can be galvanized but ASTM A490/F1852 cannot. Galvanization limitations are mainly to prevent the occurrence of hydrogen embrittlement in heavy-duty, high-strength applications.

Will Galvanized TC Bolts Rust?

The zinc-coating added through the galvanization process will reliably guard against rust for long periods of time. Eventually, all steel fasteners, even those with galvanized, anticorrosive treatments will rust at some point. Galvanized TC bolts will last significantly longer than those that are kept plain.