What are bolt grade markings?
What are bolt grade markings?
The grade of a bolt determines the maximum amount of stress (tensile strength) that the bolt can handle. The SAE marking system uses raised dashes on the bolt head to indicate strength. Metric Bolt Grades—Metric grades are set according to rules set by the ISO (International Standards Organization).
What do the markings on top of bolts mean?
The markings on the heads of bolts serve two different purposes: The markings can indicate who manufactured the bolt. This will vary from manufacturer to manufacturer, but is usually one, two or three characters. The markings can identify the standard to which the bolt was made.
What do numbers on bolts mean?
The first number in each size is the nominal or root (minor) diameter (mm) and the second number is the thread pitch (mm). NOTE: Remember that the nominal bolt diameter is the measurement of the bolt diameter as taken from the bottom of the threads NOT the top (which would be major diameter).
What grade is a bolt with 3 markings?
grade 5
Three radial lines will indicate an SAE grade 5 fastener, while six radial lines will indicate an SAE grade 8 fastener.
Whats stronger Grade 8 or Grade 5 bolt?
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.
What do 3 hash marks on a bolt mean?
@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.
How do you tell if a bolt is a Grade 8?
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. A grade 8 bolt will have 6 radial lines on its head.
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.
