Double End Stud Bolts

What is a double ended stud bolt?

The Double End Stud Bolts have threads at both ends and a non-threaded section in the middle. This design is different from the full-threaded bolts. Both types of stud bolts perform very well in their respective application fields.

Firstly, they are usually used together with two hexagonal nuts (sometimes with washers) for installation. One end can be screwed into the threaded hole of the substrate, and the other end is fixedly connected to the component with a nut, ensuring a firm fixation and uniform stress distribution.

Secondly, the ungrooved middle part helps achieve precise alignment during assembly, avoiding interference between the threads. At the same time, it can reduce stress concentration, making the stud more sturdy and less likely to break under heavy loads.

What are the main types of Double End Stud Bolts?

Let us introduce to you the main types of Double End Stud Bolts

We will explain them from the following three aspects.

（1）Classification of Thread Structures

Clamping Type: Both ends have the same threaded length, and the middle part is a plain rod. When using, both ends are tightened with nuts. This is the most common type.

Tap End Type: The lengths of the two ends of the thread are different. The longer end is used to screw into the blind hole of the component, while the shorter end is used for installing the nut.

Continuous Thread Stud: Also known as "thread rod", it means that the entire length of the rod is threaded, without any smooth section. It offers the maximum length for threaded connection.

Partial Threaded Stud: Only one end or both ends have partial threads, with a larger diameter of the smooth rod remaining in the middle.

（2）Special-purpose classification

Square Head Stud: One end has a square head. When tightening the other end, a tool can be used to grip the square head, making it convenient to install in a confined space.

Weld Stud: One end is designed for welding onto the metal substrate, while the other end has threads for connecting other components.

（3）Material and grade classification

B7 stud: Made of chromium-molybdenum alloy steel, it undergoes heat treatment and is the most common type of stud used in high-temperature (typically up to 450°C) and high-pressure working conditions.

L7 stud: Suitable for low-temperature environments.

B8 / B8M screw studs: Made of 304 or 316 stainless steel, with strong corrosion resistance.

What is a Double End Stud Bolts used for?

Double End Stud Bolts have a wide range of applications and can be seen everywhere in daily life. Here are some descriptions of their functions.

（1）Flange connection in pipeline containers

The stud passes through two flanges. Tighten the nuts at both ends to form a firm and uniform clamping force.

（2）Blind hole application

When one component has a countersunk hole (such as a cylinder head or engine block), and the other component has a through hole, the longer end of the stud will be permanently inserted into the countersunk hole. The other end is installed with a nut.

（3）Structure and equipment installation

The stud bolts are used to fix heavy equipment (such as motors, pumps or compressors) to the foundation or frame. The stud is fixed in the base (or fixed through the nuts on both sides).

（4）High pressure and high temperature environment

In the petrochemical, power generation and shipbuilding industries, double-ended studs are usually made of high-strength alloy steel (such as ASTM A193 B7) or stainless steel (B8/B8M). They can better withstand high pressure, temperature changes and vibrations.

（5）Applications requiring frequent disassembly

Any assembly components that need regular maintenance - such as inspection covers, pump casings or machine guards - are suitable for using stud bolts. You can repeatedly remove the nuts without wearing the threads.