Why prevailing torque nuts from Fixabolt?
All-metal prevailing torque lock nuts create their locking action through a controlled deformation at the top of the nut, increasing friction on the bolt thread. This is why they’re also searched for as prevailing torque lock nuts, prevailing torque hex nut, all metal locking nut, and even lock nut with metal insert (though the locking feature is usually formed in the nut itself rather than a separate insert).
All-metal locking action - no nylon to soften, melt, or swell in oils and chemicals.
Vibration resistance for machinery, plant maintenance, fabrications and general engineering.
Commonly supplied in metric sizes (often M3 to M24 depending on range).
Coarse and fine pitch options are commonly available depending on the nut series and application.
Note: prevailing torque performance can reduce after repeated use. In critical joints, follow your project spec and replace the nut if required.
What prevailing torque lock nuts are used for
Prevailing torque lock nuts are chosen where you need a mechanical locking effect that helps prevent self-loosening from movement, impact, or vibration. Typical uses include:
- General fabrication, guards, frames and brackets
- Plant maintenance and machinery builds
- Automotive and motorsport applications where drawings call up DIN 980V / ISO 7042
- Outdoor and washdown environments when paired with the right stainless grade
Because they’re all-metal, they’re often preferred over nyloc nuts in hotter zones and where oils, fuels, or solvents are present.
Standards and Materials
Standard: These nuts are commonly supplied as DIN 980V, with many suppliers referencing it as similar to or superseded by ISO 7042 / BS EN ISO 7042.
How they lock: The locking feature is typically created by deformation at the top threads (often described as a triangular indent or misalignment), producing a prevailing torque during assembly and removal.
Material grades: All-metal locking nuts are commonly offered in A2 (304) stainless and A4 (316) stainless, as well as carbon steel property classes depending on the series. Check the product options on this collection for what Fixabolt currently stocks.
Common alternative names: You may also see “inloc” or “stover” used to describe similar all-metal prevailing torque lock nuts.
Choose the Right Prevailing Torque Nut
Thread size and pitch: Match the bolt thread (metric coarse or metric fine as specified). Fine pitch is often used for better adjustment and resistance to loosening, but only when the bolt is also fine pitch.
Material grade for the environment: A2 suits most indoor and general outdoor use. A4 is typically chosen for marine, coastal, chemical, and more aggressive environments.
Strength and compatibility: Ensure the nut’s material/property class matches your bolt and the joint design. If your assembly is specified to ISO 7042 / DIN 980V, stick to that callout.
Temperature and chemicals: If nylon inserts are not permitted due to heat or chemical exposure, all-metal prevailing torque nuts are often the go-to option.
Re-use policy: Prevailing torque can reduce after use. For safety-critical or QA-controlled work, treat them as replace-when-removed unless your spec says otherwise.
Trade Supply and Support
Fixabolt supplies prevailing torque locking nuts for trade users who need consistent thread fit and reliable locking performance. Order the quantities you need for maintenance, fabrication, or production, with UK delivery and straightforward support if you’re matching a drawing callout (DIN 980V / ISO 7042).
FAQs
What are prevailing torque nuts?
Prevailing torque nuts are lock nuts that resist loosening by generating friction against the bolt thread. With all-metal types (DIN 980V / ISO 7042 style), the locking action is created by a deliberate deformation in the nut’s top threads, so it will not spin freely.
Are DIN 980 lock nuts the same as ISO 7042?
They’re commonly treated as equivalent in many catalogues: DIN 980V is often shown as similar to, or superseded by, ISO 7042 (and BS EN ISO 7042 in the UK/EU context). Always follow the standard on your drawing or project spec where it matters.
What is the difference between an all metal lock nut and a nylon insert lock nut?
An all-metal lock nut uses a formed metal locking feature (deformed threads) to create prevailing torque. A nylon insert lock nut uses a polymer ring to grip the thread. All-metal is often preferred for higher temperatures and oily or chemical environments where nylon is not suitable.
Is this a “lock nut with metal insert”?
The phrase is commonly used in search, but most DIN 980V style nuts are one-piece all-metal designs - the locking feature is formed into the nut (often described as a triangular indent or local deformation), rather than a separate insert.
Can prevailing torque nuts be reused?
They can sometimes be reused, but the prevailing torque can reduce with each cycle. For critical joints, follow the specification and consider replacing the nut once removed to maintain consistent locking performance.
What sizes do prevailing torque hex lock nuts come in?
They’re commonly stocked across a wide metric range (many suppliers list sizes from around M3 up to M24).
