Hex Flange Nut with Extended Shoulder

Core Features

Extended Tubular Shoulder – A cylindrical extension is formed integrally with the nut and flange, providing additional thread engagement length beyond the standard nut height. The shoulder is internally threaded throughout its length, enabling the fastener to accommodate longer bolt protrusions .

Integrated Flange – The flange is formed as a single piece with the nut body and shoulder, providing a load-bearing surface that distributes clamping force across the workpiece. The flange eliminates the need for separate washers in the assembly .

Hexagon Drive Configuration – The standard hexagon profile allows installation and removal using conventional wrenches or sockets.

Increased Clamping Length – The extended shoulder provides a longer clamping length compared to standard flange nuts, reducing stress concentration in bolted joints and improving resistance to thermal relaxation .

Product Characteristics

The fastener is manufactured with a hexagon body, an integrated flange at the base, and an elongated tubular shoulder extending from the flange. The shoulder is dimensioned with an outer diameter that may be uniform along its length or may incorporate a conical profile depending on the application geometry. The internal thread is produced with dimensions and tolerances following standard metric thread profiles.

The flange outside diameter and thickness are dimensioned to provide load distribution across the bearing surface. The shoulder length is variable based on application requirements, with the extended portion providing additional thread engagement for applications requiring longer clamping length.

Material composition and heat treatment processes are regulated to meet the mechanical property requirements for specified performance grades. Carbon steel grades are available for general applications, with performance grades 8, 10, and 12 providing defined proof load and tensile strength ranges. Stainless steel grade A2-70 is available for corrosion-resistant requirements. Surface treatment options include zinc plating with various chromate finishes, zinc flake coating, nickel plating, phosphate coating, and black oxide.

Application Scenarios

Thermal Expansion Applications – Used in high-temperature assemblies where thermal expansion differentials between bolted materials and fasteners may cause relaxation of bolt tension. The extended shoulder increases the effective clamping length, reducing stress increases during thermal cycling .

Heavy Equipment and Machinery – Applied in engine blocks, cylinder heads, and pump assemblies where the integrated shoulder provides additional thread engagement and load-bearing capacity.

Structural Steel Connections – Employed in building and bridge construction where flange load distribution across structural members reduces surface indentation and the extended shoulder accommodates longer bolts.

Automotive and Transportation – Used in chassis and powertrain components where the integrated flange simplifies assembly and the extended shoulder provides increased thread engagement for joint integrity.

Customization Options

Specifications and configurations can be adjusted based on application requirements. Shoulder length, flange diameter, and thread size are customizable according to application geometry. Material grades include carbon steel for general applications and stainless steel grades for corrosion-resistant requirements. Surface treatments are selectable according to environmental exposure conditions, including zinc plating with various chromate finishes, zinc flake coating, nickel plating, phosphate coating, and black oxide. Strength grades can be matched to specific tensile and yield strength criteria defined in the application engineering specifications.

Frequently Asked Questions

Q: What is the purpose of the extended shoulder on this flange nut?
A: The extended shoulder provides additional thread engagement length beyond the standard nut height, effectively increasing the clamping length of the bolted joint. This is particularly beneficial in applications subject to thermal expansion, where the increased length reduces stress relaxation in the fastener .

Q: What is the difference between this fastener and a standard flange nut with a separate spacer?
A: The extended shoulder is integrally formed with the nut body and flange, eliminating the need for separate spacer components. This integrated design reduces assembly complexity, minimizes the number of parts, and eliminates potential issues associated with separate spacer components such as misalignment or loss during handling .

Q: What is the recommended tightening torque for this nut?
A: Tightening torque values are determined by the thread size, nut performance grade, material grade, and application load requirements. The extended shoulder does not affect torque specifications; values should be obtained from engineering standards or calculation methods defined in fastener design guidelines. For applications subject to thermal cycling, torque specifications may need to account for operating temperature conditions.

Q: Can these nuts be reused after removal?
A: The nut itself is reusable, provided threads and shoulder remain in satisfactory condition. Inspection should verify that threads are free from deformation or damage. For critical applications, replacement is recommended to ensure consistent clamping performance.

Q: What are the available surface treatments?
A: Surface treatments include zinc plating (clear, yellow, black chromate), zinc flake coating, nickel plating, phosphate coating, black oxide, and others. Treatment selection is based on corrosion resistance requirements, environmental exposure conditions, and appearance specifications.

Installation Considerations

The nut should be tightened to the specified torque using a torque wrench. The flange provides a bearing surface that distributes clamping load across the workpiece. Thread condition should be inspected before installation; damaged or contaminated threads may affect torque readings and assembly integrity. For plated or coated nuts, coating thickness should be within specified tolerances to maintain thread fit.

In thermal cycling applications, the extended shoulder design provides increased clamping length. Preload should be set based on the application's operating temperature range and thermal expansion characteristics. Fastener preload should be verified after initial thermal cycles to confirm joint integrity. For applications requiring specific torque coefficients, reference values should be obtained from applicable standards for the specific thread size range.