What Are L9 Fasteners? Here’s What You Should Know

L9 fasteners by Monroe Engineering

Fasteners are often categorized according to their grade. When shopping for hex cap screws, for instance, you may notice that some of them are L9. L9 hex cap screws are commonly used in the manufacturing industry. They are strong, durable fasteners that support a variety of manufacturing applications. What are L9 fasteners exactly, and how do they differ from other types of fasteners?

Overview of L9 Fasteners

L9 fasteners are characterized by an L9 Society of Automotive Engineers (SAE) grade. The SAE has a grading system for fasteners, including hex cap screws. Some hex cap screws have a grade 2. Other hex cap screws have a grade 5 or grade 8. The highest SAE grade for hex cap screws is L9.

How to Identify L9 Hex Cap Screws

You can identify L9 hex cap screws by inspecting their head. All hex cap screws have a solid, hexagonal head. With that said, only L9 hex cap screws have a marking consisting of nine lines. The photo above shows this nine-line marking. L9 hex cap screws feature nine lines that wrap around the perimeter of the head.

Other hex cap screws may have a marking on their head as well. Rather than nine lines, though, they use different markings. Grade 5 hex cap screws have a three-line marking. Grade 8 hex cap screws have a six-line marking. Grade 2 hex cap screws, on the other hand, don’t have a marking. Grade 2 is the lowest SAE grade, and it’s the only grade that doesn’t have a head marking.

In addition to the nine-line marking, L9 hex cap screws may also feature an “L9” label. If you notice this label on a hex cap screw, it has an L9 SAE grade.

Characteristics of L9 Hex Cap Screws

The SAE grading specification requires the use of alloy steel for L9 hex cap screws. L9 hex cap screws aren’t available in aluminum or other materials. Rather, they are only available in alloy steel. With their alloy steel construction, L9 hex cap screws are incredibly strong and durable.

L9 hex cap screws have a tensile strength of 180,000 pounds per square inch (PSI). Tensile strength, of course, refers to the maximum amount of weight or pressure a fastener can sustain without failing. L9 hex cap screws have an incredibly high tensile strength of 180,000 PSI, so you can rest assured knowing that they won’t fail — even in extreme applications.

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