ThePipingMart Blog Fasteners Double End Bolt vs Castle Nut – What’s the Difference

Double End Bolt vs Castle Nut – What’s the Difference

Double End Bolt vs Castle Nut

Many options are available in the market when it comes to fastening nuts and bolts. Two such options that are commonly used are the Double End Bolt and the Castle Nut. Though they look similar, a few fundamental differences set them apart. This blog’ll explore these differences to help you understand which is best for your application.

What is Double End Bolt?

Double Ended Bolt or Double End Threaded Rod is a fastener with two threaded ends of the same size. It connects two parts and has deep internal threads to ensure that both parts are strongly connected. The length can be customized according to the desired application. It is also called Binding Head Bolts or Specialty Bolts and comes in different head types such as hexagon, square, round and countersunk heads for greater efficiency.

What is Castle Nut?

A castle nut, also known as a slotted or castellated nut, is a type of fastener with slots cut into one end. This allows a cotter pin or other securing device to be inserted across the slot, preventing loosening from vibration and other forces. Castle nuts are often used in applications such as automotive engines and assemblies where the nut is subject to frequent adjustments.

Difference Between Double End Bolt and Castle Nut


A Double End Bolt is usually a long rod or bar with threads at both ends and a plain shank in the middle. It can be used in various ways and is commonly used in scenarios where two components need to be fastened together. On the other hand, a Castle Nut is a hexagonal nut with slots on one end and a threaded bore on the other. The slots in the nut allow inserting a cotter pin or a safety wire, making it ideal for applications where vibration or rotation is an issue.


The Double End Bolt is commonly used in scenarios requiring greater strength or precision. Double End Bolts can be used with other hardware, such as nut plates, to transmit high loads accurately. Castle Nuts are primarily used as locking nuts, especially in safety-critical applications. With the addition of a cotter pin or wire, the Castle Nut can prevent unintended loosening of the fastener.


Double End Bolts are usually made from high-strength materials such as carbon steel, alloy steel, and stainless steel. They are resistant to corrosion and are incredibly durable. Castle Nuts are also made from high-strength materials and can be used in harsh environments where the fastener is exposed to chemicals and other corrosive agents.


Double End Bolts usually use nuts or nut plates. In contrast, the Castle Nut is primarily installed using pliers or a wrench. Once the Castle Nut is tightened, a cotter pin or wire is inserted through the slots, which are then bent to securely hold the pin or wire in place.


In terms of cost, a Double End Bolt is usually more expensive than a Castle Nut. This is because manufacturing double-end bolts is a more complex process, requiring additional machining or customization. On the other hand, the Castle Nut is a relatively simple component to manufacture and is, therefore, less expensive.


In conclusion, while Double End Bolts and Castle Nuts might look similar, they are designed with different applications in mind. A Double End Bolt might be the best option if greater strength or precision is required. If preventing unintended loosening of a fastener is crucial, a Castle Nut with a cotter pin or wire might be the better solution. Whatever the application, both components are made from high-strength materials designed to withstand tough environments. Ultimately, the choice between a Double End Bolt and a Castle Nut will depend on the specific requirements of your application.

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