Metric Class 10.9 Plain Steel Prevailing Torque Flange Nuts
Class 10.9 Metric Prevailing Torque Flange Nuts in Plain Steel Finish—also called flange lock nuts, all-metal locking flange nuts, stover flange nuts, or self-locking flange nuts—deliver high-strength fastening combined with reliable vibration resistance in an uncoated configuration. These nuts feature an all-metal distorted thread locking mechanism and an integrated washer flange, eliminating the need for separate lock washers, flat washers, or thread locker compounds. The plain steel finish provides maximum flexibility for applications requiring post-assembly coating, high-temperature service, or custom surface treatments.
Why Choose Plain Finish Over Zinc Plated?
While zinc plated fasteners offer built-in corrosion resistance, plain finish fasteners are the preferred choice in several key scenarios. High-temperature applications benefit from plain steel because zinc plating can off-gas, discolor, or lose integrity at elevated temperatures—plain steel maintains consistent performance without coating degradation. Post-assembly finishing such as painting, powder coating, e-coating, or hot-dip galvanizing adheres better to clean, uncoated steel surfaces. Controlled indoor environments where corrosion is not a concern can use plain fasteners at lower cost. OEM and manufacturing applications often specify plain finish when assemblies will undergo system-wide coating processes after fastener installation. Plain steel can also be oiled for temporary corrosion protection during storage and shipping.
Why Choose Class 10.9 Prevailing Torque Flange Nuts?
Class 10.9 steel provides a minimum tensile strength of 1,040 MPa (150,000 PSI) and yield strength of 940 MPa—approximately 25-30% stronger than Class 8.8 fasteners and the metric equivalent of SAE Grade 8. Combined with the all-metal prevailing torque locking feature, these nuts are purpose-built for high-stress, high-vibration environments where standard fasteners would loosen over time. The all-metal locking design withstands elevated temperatures, repeated installation cycles, and harsh operating conditions that would compromise nylon insert lock nuts. The integrated flange distributes load across a wider bearing surface, reducing stress concentration on the mating material and preventing pull-through on softer substrates.
Material & Specifications
Our Class 10.9 metric prevailing torque flange nuts are manufactured from quenched and tempered alloy steel, heat-treated to achieve the mechanical properties required for safety-critical and heavy-duty fastening applications. The all-metal locking element is formed by mechanically distorting the thread profile at the top of the nut, creating controlled interference that generates consistent prevailing torque throughout the nut's service life. The plain steel finish leaves the base metal exposed, making these fasteners ready for custom coating processes or suitable for use in applications where corrosion protection is provided by other means.
All-Metal Locking: Built for Extreme Conditions
Unlike nylon insert lock nuts that are limited to approximately 250°F (120°C), all-metal prevailing torque nuts maintain their locking performance at temperatures exceeding 500°F (260°C)—making them essential for engine compartments, exhaust systems, industrial furnaces, and other high-heat applications. Without the additional temperature limitation of zinc plating (which begins to degrade around 400°F), plain finish all-metal lock nuts offer the highest temperature capability available in a standard prevailing torque flange nut. The all-metal design also allows for limited reuse—typically 5 to 15 installation cycles depending on the specific application—making them practical for equipment requiring periodic maintenance.
Common Applications
Class 10.9 plain steel metric prevailing torque flange nuts are specified across industries where high strength, reliable locking, and finish flexibility are required:
- Automotive & Motorsports: Exhaust manifolds, turbocharger assemblies, engine components, suspension systems destined for coating
- Heavy Equipment & Machinery: High-temperature hydraulic systems, engine assemblies, components for powder coating
- Agricultural Equipment: OEM assemblies, implements scheduled for painting after assembly
- Industrial & Manufacturing: Furnace equipment, ovens, kilns, high-heat process machinery
- OEM & Custom Manufacturing: Assemblies requiring e-coat, powder coat, or paint after fastener installation
Plain vs. Zinc Plated: Quick Comparison
Choose Plain Finish when: Operating temperatures exceed 400°F, assembly will be painted or coated after installation, application is in a controlled indoor environment, or cost savings are prioritized over built-in corrosion resistance.
Choose Zinc Plated when: Corrosion resistance is needed immediately, fasteners will be exposed to moisture or outdoor conditions, or no post-assembly coating is planned.
Available Sizes
We stock Class 10.9 plain steel metric prevailing torque flange nuts in a range of popular thread sizes to cover most heavy-duty and high-temperature applications. Albany County Fasteners offers competitive bulk pricing and same-day shipping on in-stock items to keep your production on schedule.
Need a zinc plated version or alternate grade? Contact our team—with over 18 million fasteners in stock, we can help you source the right locking flange nut for your specific requirements.