What do letters on bolt heads mean?

The higher the grade, the stronger the bolt. English bolts have radial lines on their head to identify the grade, or strength class. The number of lines on the bolt head is 2 less than the actual grade. So, for example, a grade 5 bolt will only have 3 radial lines on its head.

What are customary bolt heads marked with?

US customary bolts are marked with lines or slash marks. The more lines, the stronger the bolt will be under stress. A metric bolt is marked with a numbering system. The larger the number, the stronger the bolt will be under high load or clamping stress.

What is usually stamped on the head of a special bolt?

Special bolts are usually identified by the letter “S” stamped on the head. AN bolts come in three head styles—hex head, clevis, and eyebolt.

What does a triangle on the head of a bolt mean?

RE: Grade 8 Bolt Marking Symbol CoryPad (Materials) 26 Mar 07 15:58. The triangle is the manufacturers identification.

What does 10 mean on a bolt head?

9: Metric grade to SAE grade comparison. Fig. 10: Metric bolts are marked with numbers that indicate the relative strength of the bolt. These numbers have nothing to do with the size of the bolt.

What does 3 lines on bolt head mean?

SAE J429 (Society of Automotive Engineers) bolts have radial lines, whereas ASTM (American Society for Testing and Materials) uses a combination of letters and numbers to indicate the grade. Three radial lines will indicate an SAE grade 5 fastener, while six radial lines will indicate an SAE grade 8 fastener.

Which bolt is the strongest?

The strongest commercial-quality bolt is grade 8, marked by six raised dashes; its medium-carbon alloy steel has been quenched and tempered to achieve a tensile strength of 150,000 psi.

Is a 12.9 bolt stronger than Grade 8?

Inch fasteners—those commonly used in North America—will have a grade or ASTM rating. Property class (often just “class”) specifies metric fasteners….Table 1.

Grade/Class Strength
Metric Class 10.9 Similar to Grade 8.
Metric Class 12.9 The highest metric class for strength, it exceeds Grade 8.

What is the hardest bolt you can buy?

Commercial-grade 8 bolts are the strongest option available. They’re made from medium carbon alloy steel and have markings that include six raised dashes. The psi of the bolt is 150,000, meaning that it can withstand great deals of pressure because of the way it was quenched and tempered.

What are the grades for bolt head marking?

So there you have a quick overview of the major grades from SAE J429. As a quick summary: No marking = Grade 2. Three radial lines = Grade 5. Six radial lines = Grade 8. In Part 2 of our Head Marking Series, we talk about three additional standards that deal with inch-series fasteners, ASTM A307, ASTM A354, and ASTM A193.

What does Wilson Garner grade 5 bolt head mean?

So as you can see, this bolt head has Wilson-Garner’s manufacturer mark and three radial lines. These lines indicate that the bolt is a Grade 5. Grade 5 fasteners have a minimum tensile strength of 120ksi for diameters ¼ inch through 1 inch and 105ksi for diameters over 1 inch through 1-1/2 inches.

What is the grade for a metric bolt?

Identifying bolt grades and head markings for US grades 2, 5 and 8. Metric grades 8.8.,10.9 and 12.9 (socket products).

What do head markings on fasteners tell you?

Fastener head markings usually accomplish two things: they identify the manufacturer of the fastener and the standard to which the fastener was made. We’ll talk about manufacturer head markings first, followed by fastener standards and how they govern the industry.