The Nuts and Bolts of Decoding Fastener Markings
nuts and bolts
When deciding which fasteners would be best to use for a project, there are several ways to decode their grade. All fasteners come with specific markings to help determine material, make, and grade. Some small size fasteners will not be graded with a specified strength, but larger size fasteners and specialized fasteners are meant to meet specific strength requirements. When replacing a graded fastener, use a replacement the same grade or higher.
Recognizing Bolts By Their Markings
Commonly bolts larger than ¼” are marked on top of their heads. If a bolt is not marked, it is generally a Grade 2. These are typically used for common general fastening. If a bolt contains three lines spaced at 120 degrees apart, it is a Grade 5. These could be used for high-demand, high-strength applications. Bolts with six lines spaced at 60 degrees apart are Grade 8. These are used for high-strength, specialized applications that generally require rigorous control.
Standard Fastener Grades (Top of bolt head)
This chart outlines the common grades of bolts we carry at Global Certified Fasteners.
Common Nuts Markings
Nuts are also coded by grade. On standard nuts, Grade 2 are not marked, but Grades 5 and 8 are using a clock marking system. A dot is located in a corner to indicate 12 o’clock, and a line is placed at the 5 or 8 o’clock positions to identify each grade.
Contact Global Certified Fasteners For All Of Your Fastener Needs
We also offer specialized fasteners to suit a variety of needs. We’re here to answer any and all questions to get the correct products in hand. Please call us at (708)450-9301 to discuss all of our available options.
Relevant question
What are nuts and bolts?
The bolt consists of a head and a cylindrical body with screw threads along a portion of its length. The nut is the female member of the pair, having internal threads to match those of the bolt. Washers are often used to prevent loosening and crushing. See also nut; washer.
