In the world of manufacturing and construction, bolts and nuts are essential components. They are small and mighty and play a significant role in keeping structures intact. In India, with the rise in construction and infrastructure development projects, it’s important for steel suppliers and business owners to understand the different types of bolts and nuts available and how they are used in steel structures. There are different forms of steel bolts available in the market today, each shaped and designed to cater to specific applications.

Let’s take a look at the meaning of steel bolts, how are steel bolts and nuts different, the various types of nut bolts and their industry applications.

Also read: Steel suppliers near me – List of steel suppliers in Kolkata, Delhi, Mumbai and other cities

What are steel bolts?

Bolts are fasteners, used to fasten materials. You need to twist or tighten a bolt with a nut to ensure that the given objects are fastened together.

Steel bolts and nuts are known for their strength and durability and used to fasten materials and objects for stability and longevity. Considering that there are different types of bolts in steel structures being used, it’s important to know the specific features, components and usage of bolts.

Also read: Mechanical properties of steel

Bolts vs Nuts:

Before we take a look at the types of nut bolts, let’s break down the key difference between the two.

Bolts are threaded fasteners used to assemble two unthreaded objects. Bolts require a nut to secure and fasten the objects. Nuts work with bolts to assemble and fasten objects.

In general, bolts are first inserted into pre-drilled holes. They are next tightened with nuts to keep the objects locked in place.

7 Types of bolts – Design and usage

A bolt is made of different parts – each of which contributes to its final shape and usage. The ‘Head’ is one of the main parts of a bolt and is the part which can be held for tightening or loosening. Accordingly, different types of bolts have differently shaped heads suiting the specific purpose for which it is being used: square, flat, hex, pentagon, etc.

Let’s take a look at the different types of bolts in steel structures and how they are being used across applications:

1. Anchor bolts

When it comes to using bolts for cementing structures and concrete, anchor bolts are the most preferred option. They can either be drilled or cast in place based on the nature of the connection.

They are differentiated by their unique design. One end of the bolt is embedded into the concrete thereby building a strong, secure foundation for construction. This gives stability to the structure, essential for longevity of structures such as building and bridges. In general, anchor bolts can be found at the end of steel poles.

They are available in various shapes and are indispensable to construction.

Also read: Steel frames used in construction

2. Arbor bolts

The next type of bolts we will look at are arbor bolts. These are special bolts and come with a unique design. They have a washer fixed at one end to ensure that they can securely hold saw blades. This prevents any slippage especially during rotation, providing safety and efficiency to the structure.

They also have reverse threads that distinguishes their design and purpose from other fasteners.

As can be guessed, arbor bolts are most commonly used craftmanship projects where precision and reliability are of paramount importance. Examples would include application of arbor bolts in wood work and metal work especially machinery.

3. Carriage bolts

Carriage bolts can be easily identified by their smooth, round head, partial threads around the shank, and square section underneath.

This unique design enables carriage bolts to easily lock into wood and metals. It also prevents the bolt from turning during installation.

Their aesthetic appeal makes them a common choice for woodwork, often being used in making furniture and other decorative items. They can be made of different metal types that determine their strength. Stainless steel is one of the popular carriage steel bolts types.

4. Blind bolts

Blind bolts are the next bolt and nuts type we will be looking at. Taking a cue from its name, blind bolts are used in areas that are otherwise hard-to-reach for conventional bolts.

Their design encompasses a unique expanding chamber. This allows them to secure components from one end and provide a strong hold in hollow sections. For usage, the object must come with a pre-drilled hole for the blind bolt.

Blind bolts are strong (high tensile strength), durable and versatile, making them ideal for usage in automobile and aerospace industry applications.

Also read: Steel in automotive industry – Importance, usage and types

5. Elevator bolts

Elevator bolts are the type of bolts you will commonly see in conveyor systems/belts and elevators.

They have a flat, plain head. This design makes them suitable for use in applications that require a flush surface. They fasten objects together but do not hinder operations.

For instance, in conveyor systems, these bolts make room for close contact between the belt and pulley. This ensures smooth, hassle-free operations and movement of load (goods).

Elevator bolts in conveyors can be seen in agricultural and industrial projects.

6. Flange bolt

Flange bolts are designed with an in-built washer. This enables the bolt to have a strong grip and distribute the pressure evenly across surfaces.

This unique design element streamlines the assembly process by reducing the need for separate washers.

The construction and automobile sector (e.g., vehicle engines) uses flange bolts extensively, as they help to save time while being efficient.

Also read: Raw materials used in the construction industry

7. Hex bolts

The final type of steel bolts we will look at are hex bolts.

These come with a six-sided head. They are versatile, have high tensile strength, and as a fastener, are compatible with various tools for installation and removal.

They can be used in assembling machines, structures, and other components and are available in a wide range of sizes, dimensions, and materials.

Industrial application of types of bolts in steel structures

The different types of bolts and nuts are critical to steel structures and industrial applications. They have diverse usage across industries, from agriculture to automobile and construction.

• Construction: Steel bolts are used to anchor structures to their foundations for safety and stability. In high-rises, high tensile strength bolts are used in steel beams and steel columns to resist wind and seismic forces.
• Automobile manufacturing: Bolts and nuts are used across different parts, from engine assembly to bodyworks. They not only provide safety to the structures, but also require to be used reliably to ensure performance and meet design requirements.
• Aerospace: In the aerospace sector, specialty nuts and bolts are designed to withstand extreme pressures and temperature.

How to choose the right type of bolts and nuts?

By now you understand that with multiple types of nut bolts available in the market, it’s critical for you to find the right ones for your project. Here are some factors to consider to help you decide on the right nuts and bolts:

• Material of the bolts and nuts: Understand the environment and application it is going to be used in and choose accordingly. For instance, if the bolt is being used in steel structures in marine areas, you will require corrosion resistant materials, i.e., stainless steel. However, if strength is required, carbon steel bolts are more suitable. This decision will impact the durability and longevity. (Also read: Carbon steel vs Stainless steel)
• Load requirement: If the project requires heavy load bearing capabilities, choose steel bolts with high tensile strength to handle pressure without breakage.
• Bolt size and type: This should be based on the application. Ideally, try to use the same type of bolt as the steel structure. Also, the size of the bolts and nuts should be complementary.
• Thread type: Select between coarse and fine thread. Fine threads offer strength and precision, whereas coarse threads are unlikely to be stripped.

Remember, during structural construction, even the smallest components matter. So, while bolts and nuts may appear as minor components in the large canvas, it’s important to select wisely by taking different factors into account.

Author: Sohini Banerjee

Sohini is a seasoned content writer with 12 years’ experience in developing marketing and business content across multiple formats. At Tata nexarc, she leverages her skills in crafting curated content on the Indian MSME sector, steel procurement, and logistics. In her personal time, she enjoys reading fiction and being up-to-date on trends in digital marketing and the Indian business ecosystem.