Prevailing Torque

Prevailing torque testing is a mechanical testing method used to evaluate the resistance to rotation, also known as prevailing torque, of fasteners that have special features to offer improved vibration resistance.

The main objective is to assess how well fasteners can prevent themselves from loosening when exposed to external forces or vibrations. This evaluation is especially important for threaded fasteners like nuts and bolts, which are commonly used in crucial applications where maintaining the integrity of the joint is absolutely vital.

We offer prevailing torque testing on fasteners up to sizes M20 to the following standards:

ISO 2320 Prevailing torque type steel nuts*
BS 4929-1 & 2 Steel hexagon prevailing torque type nuts*

We can combine prevailing torque testing with proof load testing on nuts, bolts, and fasteners to provide a comprehensive overview of a sample’s behaviour, and accurate data analysis.

The activities identified with * are not UKAS accredited.

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Ensuring fastener safety with Prevailing Torque

It is safety-critical that prevailing torque nuts are tested accurately for a range of complex engineering industries, including nuclear, power and energy sectors, aerospace, and marine applications. If a nut or bolt becomes loose within an aeroplane, submarine, or a nuclear reactor then there could be devastating consequences as well as risks to health, safety, and the environment.

Performing crucial prevailing torque testing on nuts means that these samples can be verified for use, and we can help to confirm that they meet the required minimum standards for these applications. Testing will also aid with the manufacturing stage of the nuts, as they can be checked and verified at the time of assembly, reducing the risk of failures, defects, or flaws.

There is an increasing demand in the energy and power sector to provide quality assurance and safe testing and verification of fasteners through prevailing torque testing.

Unlock the potential of your fasteners with our prevailing torque tests.

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What types of fasteners require prevailing torque testing?

Prevailing torque is conducted to gain insights into the mechanical and physical characteristics of steel nuts and bolts, as well as locking nuts and threads. This is achieved by measuring the torque needed to overcome friction when they are being tightened in a specific setting.

These types of fasteners are found in most industries and sectors, from construction, oil and gas to commercial applications and household items such as furniture and bikes.

Locking nuts and threads are extremely common types of fasteners. From tightening a bolt on a flat-pack piece of furniture during assembly, to manufacturing a rotating blade for a wind turbine, we see these fasteners in every industry, including construction, oil and gas, commercial and household applications.

Prevailing torque testing is an important aspect of fastener design and quality control, especially in applications where the consequences of joint failure due to self-loosening could be severe. It helps manufacturers ensure that fasteners perform reliably in demanding environments.

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Trusted reliability

BES Group is a trusted and reliable provider of NDT services. We're proud to have a proven track record of providing high-quality services that meet the needs of our customers.

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We understand that our customers may require quick turnarounds and bespoke testing services, which is why we tailor all our services to suit your needs.

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Our team of expert inspectors have decades of experience in testing, and they have the expertise to identify and interpret the flaws in your materials.