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How do you read bolt code?

How do you read bolt code?

Deciphering Bolt Codes: A Comprehensive Guide to Understanding Bolt Markings

Bolts are indispensable components used across industries, ensuring the secure assembly of structures, machinery, and equipment. Understanding bolt codes is crucial as they convey vital information about a bolt’s specifications, materials, and capabilities. Let’s explore the elements of bolt codes and decipher how to read them accurately.

What is a Bolt Code?

A bolt code comprises alphanumeric characters and symbols that convey essential details about a bolt’s characteristics. These markings are typically stamped or imprinted onto the head or shank of the bolt.

Elements of a Bolt Code:

  • Grade or Material Identification: The first few characters often indicate the bolt’s grade or material composition. For instance, markings like “8.8,” “10.9,” or “A325” signify specific grades or materials the bolt is made from.
  • Strength Class: Numerical values within the code, such as “8.8” or “10.9,” represent the bolt’s strength class. The numbers correspond to the bolt’s tensile strength in metric units (in megapascals), indicating its ability to withstand loads.
  • Manufacturer’s Mark: Some bolt codes include the manufacturer’s symbol or name, ensuring traceability and quality assurance.
  • Size and Thread Pitch: Information regarding the bolt’s size, diameter, and thread pitch might be part of the code. For example, “M12x1.75” indicates a bolt with a 12-millimeter diameter and a 1.75-millimeter thread pitch.
  • Additional Markings: Depending on the bolt’s specific standards and certifications, additional symbols or markings, such as country of origin, might be included.

How to Read a Bolt Code:

1. Identify the Grade or Material: The first set of characters typically denotes the grade or material of the bolt. For instance, “8.8” represents a bolt made of medium carbon steel with a minimum tensile strength of 800 megapascals.

2. Interpret the Strength Class: The numbers in the code signify the bolt’s strength class, determining its load-bearing capacity. Higher numbers indicate higher tensile strength and load-bearing capabilities.

3. Decipher Size and Thread Pitch: Look for indications of the bolt’s diameter (measured in millimeters) and thread pitch (distance between threads in millimeters).

4. Understand Additional Markings: Check for any additional symbols or markings that may provide further information about the bolt’s standards, certifications, or origin.

Importance of Reading Bolt Codes:

  • Quality Assurance: Understanding bolt codes ensures that the right bolts with the appropriate strength and material are used for specific applications, ensuring structural integrity and safety.
  • Compatibility: Reading bolt codes helps in selecting compatible bolts for various assemblies, ensuring proper fitting and functionality.
  • Traceability: Bolt markings assist in traceability, enabling identification of the bolt’s manufacturer, standards compliance, and adherence to specifications.


Bolt Codes serve as a roadmap to understand a bolt’s characteristics and capabilities. Mastery of these codes empowers engineers, contractors, and manufacturers to select the right bolts for specific applications, guaranteeing safety, reliability, and compliance with industry standards.

In essence, learning how to read and interpret bolt codes is an essential skill for anyone involved in construction, engineering, or manufacturing. It ensures the proper selection and use of bolts, contributing significantly to the stability and safety of assembled structures and machinery.

Bhansali Metalloys Inc is one of the leading Manufacturer, Exporters, and Suppliers of High Quality Bolt Codes all over in India. We are Manufacturer, Supplier and Dealer of various types of Fasteners such as Bolts, Nuts, Threaded Rods, Screws, Washers and many more. We are Bolt Codes Manufacturer in India. These Bolt Codes are available in different grades and materials. We are Bolt Codes Manufacturer, Supplier, Dealer, and Exporter in India. We are Bolt Codes Supplier in India. Contact Us +919152160158 or email to for M20 Thread Size price list.

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Each Stainless Steel Bolt Codes is otherwise designed based on the characteristics of the applying and additionally the pressure. Consequently, different industries use different Bolt Codes. We also produce customized Bolt Codes Products at our factory as per our client’s requirements. For any types of Bolt Codes Price List Call on +91 9152160158 or drop an Email to |

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