Flange Nut[3]

Updated: 2026-09-11

Overview

Flange nuts are threaded fasteners with an integrated flange at one end, designed to replace the need for a separate washer. The flange acts as a built-in bearing surface, distributing clamping pressure evenly and reducing the risk of damage to the assembled parts. These nuts are standardized under GB (Guobiao) in China, ensuring compatibility with metric threaded bolts and screws. Widely used in industries requiring vibration resistance, such as automotive manufacturing and heavy machinery, flange nuts offer superior performance compared to standard nuts. Their design minimizes loosening caused by dynamic loads, making them a reliable choice for critical applications.

Structure and Working Principle

A flange nut consists of two main parts: the threaded body and the flanged base. The flange is typically serrated or smooth, with serrations providing additional grip to prevent rotation. The nut works by threading onto a bolt or stud, with the flange creating a larger contact area against the surface of the joined material. This design reduces localized stress and distributes the load more evenly, which is particularly beneficial for softer materials like plastics or thin metals. The serrated flange version bites into the surface, offering enhanced resistance to vibration-induced loosening, a common issue in moving assemblies.

Key Features

Flange nuts are valued for their multifunctional design, combining the roles of a nut and washer into a single component. This integration simplifies inventory management and speeds up assembly processes. The serrated flange variant is especially effective in high-vibration environments, such as engine components or structural frameworks. Materials range from economical carbon steel (often zinc-plated) to corrosion-resistant stainless steel (A2/A4 grades) and brass for electrical conductivity. The GB-standard versions adhere to strict dimensional tolerances, ensuring interchangeability with other metric fasteners in the global market.

Application Areas

Primary applications include automotive systems (e.g., engine mounts, exhaust assemblies), industrial machinery (pump housings, conveyor systems), and construction (steel frameworks, scaffolding). Their vibration-resistant properties make them indispensable in aerospace and rail industries, where safety is paramount. In electrical installations, brass flange nuts are preferred for grounding connections due to their conductivity. The food processing and marine sectors often opt for stainless steel variants to withstand corrosive environments like saltwater or acidic cleaning agents.

Maintenance and Precautions

Regular inspection is recommended for flange nuts in high-stress applications to check for wear or deformation. Reuse is generally acceptable if threads and flange remain undamaged. For critical assemblies, follow manufacturer torque specifications to avoid joint failure. Avoid mixing materials (e.g., steel nuts on aluminum bolts) to prevent galvanic corrosion. When disassembling, replace serrated flange nuts if the teeth show significant wear, as their anti-loosening capability diminishes over time. Lubrication is rarely needed unless specified for high-temperature environments.

B2B Procurement Guide

Bulk buyers should specify GB standards (e.g., GB/T 6177 for metric series) alongside material grades and plating requirements. MOQs typically start at 1,000 units for standard sizes, with discounts available for larger orders. Lead times vary from 2–6 weeks for custom finishes like hot-dip galvanizing. Quality checks should include thread gauge testing, flange flatness verification, and salt spray tests for corrosion resistance. Reputable suppliers provide mill certificates for material traceability. Eco-conscious buyers can request RoHS/REACH compliance documentation for regulated markets.