Table of Contents
What do the marks on a bolt head 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.
What do the markings on a nut mean?
Fasteners commonly have two different markings: a unique manufacturer identification symbol – such as letters or an insignia – and information about the fastener strength. Such markings differ based on how the fasteners were made.
What are bolt grade markings?
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.
How can you tell the difference between Grade 5 and Grade 8 bolts?
Grade 8 / Grade G Grade 8 bolts have been hardened more than grade 5 bolts. Thus they are stronger and are used in demanding applications such as automotive suspensions. Grade 8 bolts have 6 evenly spaced radial lines on the head. Grade G is roughly equivalent to Grade 8.
Do nuts have grade markings?
Grade 2 nuts are not required to be marked for grade identification. Grade 5 nuts shall be marked with three circumferential dashes equally spaced 120˚ apart. Grade 8 nuts shall be marked with six circumferential dashes equally spaced 60° apart.
How do you read a bolt grade?
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 does 7 on a bolt head mean?
The marks approximately correspond to the following property classes: Head Mark “4”: 4.6, 4.8, 5.6, 5.8, 6.8. Head Mark “7”: 8.8. Head Mark “8”: 9.8. #2.
What does 8.8 mean on the head of 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 is a Class 8 nut?
Class 8 nuts are intended for use with screws and bolts of property class 8.8 or lower. They are widely used in the automotive and electronics industries. : 0.58% maximum; Manganese: 0.25% minimum; Phosphorus: 0.060% maximum; Sulfur: 0.150% maximum.
How can you tell if a lock nut is Grade 8?
Grade 8 nuts shall be marked with six circumferential dashes equally spaced 60° apart. class equal to or higher than class 8 shall be marked on one surface with the class identification number.
What is a Grade B nut?
Strength exceeds Grade 2. ASTM A325. Bolts meet ASTM A325 Type 1 standards for structural steel joints. Grade B Nuts. Strength is similar to Grade 5.
What do the grades on bolts mean?
The nominal size of the grade 8 bolts can be from 1/4″ to 1 1/2″. The minimum yield strength of this grade bolt is 130,000 psi. A maximum of 120,000 psi of tensile force (proof load) can be applied to grade 8 bolts. Grade S – Grade S bolts have the capability to withstand 45 to 49.9 MT of stress per 6.45 cm3.