Glossary

A U-bolt is a U-shaped fastener with threads on both ends, designed specifically to secure pipes, tubes, and other cylindrical objects. It functions by wrapping around the object to be secured, with its threaded ends passing through a support structure. Nuts are then tightened onto the threads, creating a powerful clamping force that holds the object firmly in place. This design effectively distributes the load and provides excellent resistance to movement and vibration.

Because of their simple yet robust design, U-bolts are a versatile fastening solution used across many industries. They come in various types, including round bend for pipes, square bend for rectangular materials, and semi-round for wider objects. They are widely used in plumbing, automotive (for things like leaf springs), and construction to secure everything from conduits to structural beams.

A U-nut, also known as a U-nut clip or a speed nut, is a type of self-retaining fastener designed to be clipped onto the edge of a sheet metal panel. Shaped like the letter "U," it consists of a spring-steel clip with a threaded impression or a tapped barrel that receives a screw.

Unlike traditional nuts that require a wrench to hold in place, U-nuts simply clip onto a panel, creating a secure, threaded mounting point. This design makes them ideal for applications where access to the back of the panel is limited or where a faster, more efficient assembly process is needed. They are particularly effective in resisting vibration and will not turn as a screw is being driven, ensuring a quick and reliable connection.

U-nuts are widely used in a variety of industries, including automotive for securing trim panels and dashboards, in appliances, and in furniture assembly. They are a cost-effective and versatile solution for creating a strong, yet easily removable, attachment point on thin materials without the need for welding or special tools.

Ultrasonic Testing (UT) is a non-destructive testing (NDT) method that relies on high-frequency sound waves—typically between 0.5 and 25 MHz—to evaluate materials without causing damage. A transducer generates ultrasonic waves that are directed into the test material, and whenever these waves encounter a boundary such as a crack, void, inclusion, or even the back wall of the material, part of the energy is reflected back. The reflected signals are captured by the same or a separate transducer and displayed on a screen, allowing technicians to determine the presence, size, and depth of internal flaws. This ability to “see” inside a material makes UT one of the most sensitive and widely used inspection methods for detecting cracks, porosity, inclusions, and other discontinuities that could compromise performance.

Beyond flaw detection, UT is also used to measure thickness—an essential function for monitoring corrosion in pipes, tanks, and pressure vessels—and for material characterization. Its applications span industries such as aerospace, automotive, construction, and energy, where precision and reliability are critical. UT offers several advantages: it is highly sensitive to small flaws deep within materials, provides accurate depth and dimensional information, and is portable and safe compared to radiation-based methods. These qualities make ultrasonic testing a vital quality-control tool for ensuring the integrity and safety of components in demanding industrial environments.

A standard thread form with a relatively wide pitch, meaning fewer threads per inch compared to fine threads of the same diameter. UNC threads are commonly used in general-purpose fasteners due to their strength, ease of assembly, and better resistance to stripping in softer materials.

A standard thread form with a tighter pitch, meaning more threads per inch than coarse threads of the same diameter. UNF threads are typically used when a higher level of strength or a more precise fit is needed, especially in applications with limited space or requiring greater tension control.

A custom thread series defined by a unique combination of diameter and pitch that doesn’t match standard UNC or UNF series. UNS threads are used when specific design or performance requirements call for non-standard thread dimensions.

A high-strength fastener featuring a built-in flange under the hex head, which distributes the clamping load over a wider area and removes the need for a separate washer. Earnest Machine’s USA-Made Hex Flange Screws are manufactured in the United States, fully DFARS compliant, and available in Grade 8 with a Phos & Oil finish.

These screws are cold-formed with an indented head to ensure a fully formed hex and uniform flange thickness. They are engineered to meet IFI-111 and ASME B18.2.1 dimensional standards, making them ideal for demanding applications such as securing components to truck frames.

A high-strength metric fastener with a heavy hex head and integrated flange designed to spread the clamping load across a wider area, eliminating the need for a separate washer. Earnest Machine’s USA-Made Metric Heavy Hex Flange Bolts are manufactured in the United States, fully DFARS compliant, and available in Property Class 10.9 with a Phos & Oil finish.

They are engineered to meet the dimensional requirements of ASME B18.2.3.9M and are produced with a cold-formed indented head to ensure a fully formed hex and uniform flange thickness.

A USS flat washer is a type of washer that conforms to the United States Standard (USS), an older set of guidelines established before the SAE standards became more widely adopted. Like SAE flat washers, USS washers are flat, circular pieces of metal (usually steel, stainless steel, or sometimes other materials) with a central hole, used under a bolt head or nut to distribute load, protect surfaces, and help prevent loosening.

USS Hardened Washers are otherwise known as Wide Heat Treated Washers, Wide Through Hardened Washers, and Wide Hardened Washers. The USS Hardened Washers are through hardened for Grade 8 or better applications — preventing imbedding or distortion to the washer and material being clamped. Without washers, bolts and screws can lose their clamping load if they imbed into the clamping material. The washer provides a smooth level and wide protective bearing surface to tighten nuts and bolts.

A USS NT Hardened Flat Washer is a type of flat washer designed to provide a smooth surface and distribute the load of a fastener over a larger area. The "USS" refers to the United States Standard for washers, which defines the dimensions and tolerances. The "NT" stands for "Non-Tensile," indicating that the washer is not specifically designed to handle tensile stress but rather to provide a stable and uniform bearing surface.

The USS NT2 Hardened Thick Flat Washer (RC 38-45) is a durable, hardened washer designed for high-strength applications. Its thick design distributes loads effectively, while the hardened material (Rockwell hardness 38-45) ensures resistance to wear and deformation. This washer is commonly used in heavy-duty construction, industrial machinery, and infrastructure projects where high stress and vibration are factors.

A USS NTX Hardened Extra Thick Flat Washer (RC 38-45) is a specialized type of flat washer designed for heavy-duty applications where strength, durability, and load distribution are critical.