What do the markings on nuts mean?

Bolt heads and nuts are often marked with numbers, letters, dashes, slashes, dots, or an assortment of other marks. Fasteners commonly have two different markings: a unique manufacturer identification symbol – such as letters or an insignia – and information about the fastener strength.

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.

What does JDF on a bolt mean?

The three slashes that you see on this head, that indicates that it’s a grade 5 bolt. This is a great 8 bolt. Again you see JDF on that bolt on the top. Those initials again are manufacturers marking to indicate that this is their bolt and then you see 1, 2, 3, 4, 5, 6 slashes indicating it’s a grade 8.

Do nuts have grade markings?

Grade A nuts are used with low carbon steel heavy hex bolts. Grade 5 are used with medium carbon cap screws and bolts. Grade C nuts are recommended to be used with A325 structural bolts. Grade 2H nuts are recommended for use in high pressure and high temperature service.

What does the 8 mean on a nut?

SAE Grade 5 and 8 nuts are. required to be grade identified, using the “clock” marking system. A dot is located at one corner on the top surface to indicate, 12. o’clock, and a radial line is placed at the 5 and 8 o’clock position to. identify Grades 5 and 8 respectively.

What do the numbers mean on nuts and bolts?

They both use numbers to grade their bolts – the higher the number, the higher the tensile strength. For instance, the SAE system covers diameters of up to 1 ½ inch, and a grade 8 would have a higher tensile strength than a grade 5.

What does 307A mean on a bolt?

Low carbon steel
Bolt Grade Markings and Strength Chart

Head Marking	Grade and Material	Mechanical Properties
Min. Tensile Strength (psi)
	307A Low carbon steel	60,000
No Markings	Grade 2 Low or medium carbon steel	74,000
60,000

How do you read bolt numbers?

The diameter is denoted by the number following AN. Thus AN3 means a bolt with 3/16 inch diameter. The number following the dash indicates the length in eighths (1/8) of an inch up to 7/8. If a bolt is longer than an inch the first digit is the number of inches and the second digit is the number of eighths.

What do the numbers mean on bolts?

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 is a grade 10 nut?

Class 10 nuts are metrics nuts with a steel grade equivalent to the SAE grade 8 classification. These are high-strength steels used in the automotive and structural industries.

What is a class 5 nut?

Grade 5 Hex Nut, Plated. SAE J995 Grade 5 hex nuts are medium strength nuts manufactured from quenched and tempered medium carbon steel. Grade 5 hex nuts are available in diameters from 1/4″ through 1 1/2″ inclusive. Dimensional specifications are governed by ASME B18.

What is a #10 nut?

US Nut Size Table

Size	Diameter*
Hex Nut	Machine Screw Nut
#8	–	11/32″
#10	–	3/8″
#12	–	7/16″

How do you read a bolt number?

Determine the diameter of the bolt by looking at the first number. For example, if the metric bolt was M14x1. 5×25, it would have a diameter of 14 millimeters. Determine the distance between threads by looking at the second number.