The Technique Behind Marking the Grade System for Bolts and Fasteners

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Bolts are exterior male-threaded steel fasteners. They are used to assemble two unthreaded items, generally with the help of a nut. Choosing the right bolt quality ensures a robust, long-lasting connection between two materials.

Bolt Grade System

Bolts may be made out of a variety of steel grades. The grade of a bolt specifies the maximum amount of stress (tensile strength) it can withstand. The amount of pull a bolt can withstand before breaking is measured in enduringness. The method for adjusting the bolt is also determined by the bolt’s grade. The grades are marked by raised numerals or dashes on the top of the bolts.

At Fair Wind Fastener you will find the best quality nuts, fasteners, and Silicon bronze hex bolts based on their grades. You simply need to know your requirements and the bolt grade to narrow down your selection choice. It is a private business situated in Newport, Rhode Island, therefore the owner of the business connects directly with the customer. This makes clients’ life much easier as they skip the customer services part and deal with the owner directly who knows everything about fasteners.

The three primary categorization systems for bolts are SAE, Metric, and ASTM –

  • SAE Bolt Grade – In the United States, the criteria for bolt strength grades are established using a system designed by the SAE (Society of Automotive Engineers). To indicate strength, the SAE marking method uses raised dashes on the bolt head.
  • Metric Bolt Grades – Metric grades are established by ISO guidelines (International Standards Organization). The grade has two numbers divided by a dot. The property category is represented in raised or depressed numbers on the top or side of the bolt head.
  • ASTM Bolt Grades – The American Society for Testing and Materials established the ASTM grade standard. The letter A and three digits sealed on the bolt head show its strength classes.

Markings of Bolt Grades

The SAE system is the most common grading method for bolts used in the United States. However, you will also come across metric grading schemes.

  • Bolts come in a variety of grades, but the three most frequent for SAE are 2, 5, and 8.
  • Metric is divided into five categories (grades): 5.8, 8.8, 10.9 as well as 12.9. Regardless of how the system grades the bolts, the higher the range, the stronger the bolt.
  • ASTM noted fasteners are depicted with letter A. A2/Type 304 stainless, A4/Type 316 stainless, and A-307B Hex Cap Grades

If you ever feel that you have doubts related to the right fastener to be chosen for the repairing or manufacturing of a product, always consult with the distributors. Fastener distributors have enough knowledge about various nuts, screws, bolts, and fasteners along with their grades to understand, which product goes well with marine construction, saltwater, humid environment, construction, electric or plumbing, or any other task that require nuts and bolts.

This article was simply to give you an overall look at grades decided for every bolt and fastener. If you ever need the help of bolt knowledge, this is the right place to go through once more.


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