Table of Contents

## What do the numbers on nuts mean?

The number has nothing to do with the size, but does indicate the relative strength of the bolt. The higher the number, the stronger the bolt. Some metric nuts are also marked with a single-digit number to indicate the strength, and some may have the M and strength grade embossed on the flats of the hex.

**What are bolt grades?**

The grade of a bolt determines the maximum amount of stress (tensile strength) that the bolt can handle. Tensile strength is the amount of pull the bolt can withstand before breaking. The method used for tightening the bolt is also dependent upon the grade of the bolt.

### What does 8.8 mean on a bolt?

So, in English, a Property Class 8.8 bolt is a bolt with a nominal tensile strength of 800 MPa and a nominal yield strength that is 80% of that nominal tensile strength, so 640 MPa.

**What do the letters on top of bolts mean?**

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.

## How do you read metric bolt numbers?

Metric Bolt Sizes

- The letter ‘M’ indicates that this bolt uses a metric thread.
- The number ‘8’ refers to the nominal diameter of the bolt shaft in millimeters.
- The number 1.0 is the thread pitch of the bolt, which is the distance between threads, in millimeters.
- And the final figure, 20, is the length in millimeters.

**What do markings on bolts mean?**

### What size is M22 in inches?

Tap size | Basic major dia (mm) | Basic major dia (inch) |
---|---|---|

M22 x 2.5 | 22mm | .8661 |

M22 x 1.5 | 22mm | .8661 |

M24 x 3 | 24mm | .9449 |

M24 x 2 | 24mm | .9449 |

**What does M20 bolt mean?**

M10-1.0 x 20 M = This designates the fastener is a metric size. 10 = The nominal diameter in millimeters. 1.0 = The thread pitch, or distance between threads, in millimeters. 20 = The fastener’s length, in millimeters.

## What does B on a bolt head mean?

ASTM A307 Grade B Grade B bolts and studs have a tensile strength between 60 ksi and 100 ksi.

**What do the markings on top of bolts mean?**

### What is strongest steel bolt?

Grade 9 Bolts Grade 9 structural bolts, also known as grade 9 hex cap screws, are one the strongest structural bolts that can be used today. While the typical grade 8 bolt has a tensile strength of 150,000 PSI, a grade 9 bolt has a tensile strength of 180,000PSI.

**What is the strength grade of a bolt?**

Bolt strength grade is an international standard. Strength grades 8.8 and 10.9 refer to shear stress grades 8.8 and 10.9 GPa for bolts.8.8 nominal tensile strength 800 N/MM2 nominal yield strength 640N/MM2.

## What are the classifications of bolts?

The bolts of class 8.8 and above are called high-strength bolts which made of low or medium carbon alloy steel after heat-treated (quenched and tempered).

**How do you compare US/metric screws and bolts?**

Chart for easy comparison of US / Metric screws and bolts. It is always a bit unusual to compare them as they use different measurement systems (PSI vs. Mpa). Proof Load: An axial tensile load which the product must withstand without evidence of any permanent set.

### How do you calculate the tensile strength of a bolt?

The letter “X.Y” indicates the strength of the bolt, X*100= the tensile strength of the bolt, X*100* (Y/10)= the yield strength of the bolt (as specified: yield strength/tensile strength =Y/10). For example, the tensile strength of class 4.8 bolts is 400MPa; Yield strength: 400*8/10=320MPa.