The phrase ‘bent bolt’ typically brings to mind an image of a normal bolt fastener that has been damaged, deforming it in some way. While that is often the case, there is in fact an entire family of bolting fasteners designed with bends and sweeps in their profiles, where the phrase ‘bent bolt’ can be used as well. We’ll discuss these engineered bent bolt fasteners, their application categories, and their common materials and finishes in our article below.
Bent Bolt Styles and Types
A bent bolt is described as a solid rod formed to a specific shape or profile, with at least one end threaded for use in a fastening application. The threaded ends most often receive standard hex nuts and washers, allowing the bent fastener to function as a bolt, compressing down against a flat surface such as a base plate. The end opposite of the threads is most often intended to interfere with another material or component, such as being cast firmly into concrete or clamping down against other rigid material. In other applications, the bare end serves as an attachment point, such as in suspending a cable or rope. In the below table, we’ll describe the common bent bolt styles and some of their most common applications.
Threaded on one end and featuring a 90 degree bend at the other end, the L-Hook is most often used as a concrete-embedded anchor to hold down steel building structural materials. Small diameter, lighter duty L-Hooks are often called “utility hooks”, used for any attachment or hanging function in general commercial or residential use.
|Square Hook |
Similar to an L-Hook but with an additional leg segment on the end, the Square Hook is often used interchangeably as a utility hook for light duty applications where additional retention potential is beneficial. In industry, the Square Hook can be used in low-risk attachment positions, such as securing a square support channel to a larger beam to hold up light fixtures or signage.
|Round Hook |
Offering the same functionality as the Square Hook for retention and low-risk attachment, the Round Hook is better suited to securing round profile materials, such as bolting down a small electrical conduit to a machine frame.
|Round U-Bolt (commonly U-Bolt) |
A U-Bolt is most commonly used to secure against a round profile material, equally useful in either attaching something else to the round material, or attaching the round material to something else. In other words, the round material can either be the component giving support, or being supported. For example, you might find a U-Bolt attaching a round pipe down to a fixed hanger channel, or attaching a small placard to a fixed round post.
|Square U-Bolt |
Functioning the same as a U-Bolt above, the Square U-Bolt is intended for use with square profile materials, again in either direction of giving or gaining support. Square fence posts and rectangular structural tubing are good examples of square-edge materials that a Square U-Bolt can be used with.
|Closed Eye Bolt |
Most often used as an attachment point for rope, cable, cord, or rigging hardware such as a clevis clamp, the Closed Eye Bolt requires the attaching material to be passed through the eye, fully containing it and not allowing an accidental disconnection.
|Open Eye Bolt |
Identical to the above variant, the Open Eye Bolt differs in design by featuring an open throat through which the attaching material can be inserted and removed freely without having to entirely pull through the eye. This design is useful for low-risk lifting or hanging applications by offering quick removal of the rope or cable.
A J-Hook is nearly identical to the Open Eye Bolt in function, with one minor difference: the end of the eye shape is bent straight instead of rounded, offering a larger throat opening.
|Custom Shape Bent Bolt |
For special application most commonly found in custom machine / equipment fabrication and structural anchorage, the Customer Bent Bolt offers any unique attachment or fastening features needed.
For any of the above bent bolt types, material choices parallel the most common options found in general bolt categories. For industrial and structural applications, carbon steel, steel alloys, and stainless steel materials are the typical selections here, readily available across all styles above in diameters 1/2” through 2”. Many bent bolt fabricators offer made-to-order bent bolts up to 4” diameter, and have additional options for unique finishes or coatings. Light commercial, hobbyist, and architectural versions of bent bolt fasteners can be readily found at hardware outlet down to 1/8” diameter, and in additional materials such as brass, aluminum, and a host of plastics.
Need help specifying and selecting your bent bolt project materials? E&T Fasteners offers expert opinions on standard and custom bent fasteners, along with all of the available material, finish, thread, thread locking, and hardware details, helping you build out a complete project order in one stop. Contact us to discuss your application, or to see our standard fastener offerings, visit our product selection here.
Bent Bolt Application Categories
As with any bolting application, there are a wide range of technical standards and codes that may be involved in specifying the right bent bolt for your project. To start weeding through the standards, let’s divide the bent bolt topic into categories of applications.
Knowing what job the fastener will be employed to perform is helpful in narrowing down some of the material, finish, and style options to those that best meet the job. For example, a bent bolt that is planned to be embedded in concrete will have different standards than a bent bolt planned to fasten parts on a vehicle. While listing the full suite of applicable codes to these categories is beyond the scope of this article, please reference these categories when contacting your engineer or distributor, and they should be able to assist from there. Here are the general categories:
|Structural Anchoring and Retention||Structurally rated and tested, these bent fasteners comply with ASTM structural material standards and building / construction codes. Typically, these fasteners will be high tensile strength steel material and with an applied finish designed to resist corrosion when embedded in concrete or exposed to weather. Examples include embed anchor hooks for building columns, and hook bolts for attaching tension cables on a bridge.|
|General Fastening and Hanging||Low-load or non-load rated, these bent fasteners comply with general ASTM or similar material standards, and often are not governed by any trade codes. Some variants of these fasteners may have third-party approvals when used in certain kits or equipment bundles, such as UL listing. These fasteners come in a variety of materials and finishes, usually chosen on the basis of cost and application-specific requirements. Examples include hanger hooks for overhead piping supports, and square bolts used for attaching a sign to a square post.|
|Rigging and Lifting||Rated for the high stresses that come along with lifting and rigging heavy equipment safely, these bent fasteners comply with OSHA and ASME rigging standards as well as building / construction / rigging codes. These fasteners are extra heavy-duty, mainly available in steel with painted or galvanized finishes, and are specifically tested for the shock of a dropped load. Examples include embed lifting hooks and eyes installed in concrete walls and ceilings, used as attachment points for lifting equipment.|
|Vehicle and Transportation||Specific to automotive, aerospace, and commercial vehicle applications, these bent fasteners comply with SAE (Society of Automotive Engineers) standards. Low to medium carbon steel materials are most common, with plain, plated, or galvanized finishes. These fasteners are specifically tested for the vibration, temperatures, and other stresses that are associated with the vehicle type they’ll be used on. Examples include U-bolts that support a car’s exhaust pipe, and main-frame L-hooks used on freight truck trailer decks.|
Each category above has a multitude of possible sub-categories and associated specific standards, so it is recommended to discuss your application with your distributor or specifying engineer in order to land on the correct standard for your project.
E&T Fasteners is here to help you navigate bent bolt fastener options to best meet your application and project needs. Price quotes, availability, lead times, delivery confirmations, unique application suggestions – whatever your need, we’re here to take your call or email. For support and advice from our fully trained staff, speak with an E&T sales representative today.
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