What do the letters on bolt heads mean?

What do the letters on bolt heads mean?

You can usually figure out the grade, or strength, of a bolt by looking at the markings on its head. English bolts (U.S.S. or S.A.E) are categorized by grade, from grade 2 to grade 8, where the grade represents inch strength. The higher the grade, the stronger the bolt.

What do the numbers on top of bolts mean?

Bolt Grade Markings Each grade has a specific bolt strength. No matter the system used to grade the bolts, the higher number means the stronger the bolt. For most home and automotive applications, you won’t need anything more than a grade 8 bolt strength or metric class 10.9.

Why do Grade 5 bolts have 3 marks?

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.

What does 3 marks on a bolt head mean?

Grade 5 bolt
The markings can identify the standard to which the bolt was made. For instance, if a bolt head contains three radial lines, then it’s a Grade 5 bolt. If it contains five radial lines, then the bolt is Grade 8.

Is Grade 8 or 8.8 Stronger?

Table 1.

What does the grade marking on a bolt head mean?

Our second example, Figure 3, will actually have a grade marking: 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.

What do manufacturer head markings mean on fasteners?

Manufacturer Head Markings. The Fastener Quality Act mandates that manufacturers mark each fastener with a symbol to identify the company that made it. Each company has a unique identifier that they stamp onto the head of all the fasteners that they make.

What is a Grade 2 head marking?

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 do the markings on a Wilson-Garner bolt mean?

Here we have a bolt head with the Wilson-Garner manufacturer mark and six radial lines. These radial lines indicate that the bolt is a Grade 8 bolt. A quick aside – You may notice that in the images the WG mark has been moved around a bit to accommodate the grade markings.

What does 8.8 on bolt head mean?

So, in English, a PC 8.8 bolt is a bolt with a nominal tensile strength of 800 MPa and a nominal yield strength that is 80% of the bolt’s nominal tensile strength, or 640 MPa.

What do 3 hash marks on a bolt mean?

grade 5
@Mike- The three hash marks indicate grade 5, the triangle with a swirl is the manufacturer’s stamp for Bowman Distribution. They are a distributor that has private label bolts made with their head mark.

What does 4.8 mean on a bolt?

For example, a bolt with a performance grade of 4.8 means: The nominal tensile strength of bolt material is 400 MPa. The yield-strength ratio of bolt material is 0.8. The nominal yield strength of bolt material is 400 x 0.8=320 MPa.

Is Grade 8 the strongest bolt?

A grade 8 bolt is the highest grade SAE bolt. Grade 8 bolts have a minimum tensile strength of 150,000 PSI. As a comparison, the ASTM A325 bolt is roughly equivalent to the SAE grade 5. A grade 8 bolt would be one that meets ASTM A490 standards.

What grade is a bolt with 3 markings?

Grade 5
Bolt Grade Markings and Strength Chart

What’s the difference between 4.8 and 8.8 bolts?

8.8 nominal tensile strength 800N / mm2; nominal yield strength 640n / mm2. For example: grade 4.8, the tensile strength of the bolt is 400MPa; the yield strength is 400 * 8 / 10 = 320MPa.