Specification: ST5.5-24*50

Material: SUS410

Surface Treatment: Silver Dacromet

Single weight：12.27(without the washer), 13.32(with the washer)

Product Introduction

The Hex Head With Washer Three-Clawed Thread Self-Drilling Screw With EPDM Washer 5# Tail is designed for heavy-duty metal-to-metal fastening applications requiring enhanced sealing and weather protection. The hex head provides high torque transmission capability, while the integrated EPDM washer creates a watertight seal that prevents moisture ingress through the fastener penetration point. The three-clawed thread design provides improved thread engagement and resistance to loosening in structural applications. The 5# tail features an extended drill point that provides enhanced drilling capability for thicker material stacks, enabling efficient penetration into heavier gauge substrates. The self-drilling point drills and taps threads simultaneously, eliminating pilot hole requirements. Manufactured from SUS410 stainless steel with silver Dacromet surface treatment, this screw provides hardness and corrosion resistance for demanding outdoor environments. The ST5.5-24 thread specification with 50mm length offers engagement for structural connections and heavy-duty metal assemblies requiring weatherproof sealing.

Core Advantages

EPDM Washer Integration

Integrated sealing washer creates a watertight seal that prevents moisture ingress through the fastener penetration point.

Three-Clawed Thread Design

Improved thread engagement and resistance to loosening in structural applications for secure connections.

5# Tail Extended Drill Point

Enhanced drilling capability for thicker material stacks enables efficient penetration into heavier gauge substrates.

Hex Head High Torque

Enables positive engagement with standard hex socket tools for high torque transmission and secure fastening.

SUS410 Stainless Steel

Provides hardness for metal fastening applications with corrosion resistance for demanding environments.

Silver Dacromet Coating

Provides high corrosion resistance with extended salt spray protection and a silver metallic aesthetic finish.

Product Features

EPDM washer integration Integrated sealing washer creates a watertight seal preventing moisture ingress through the fastener penetration point for weatherproof connections.

Three-clawed thread design Improved thread engagement and resistance to loosening provides secure fastening in structural applications.

5# tail extended drill point Enhanced drilling capability for thicker material stacks enables efficient penetration into heavier gauge metal substrates.

Hex head configuration Positive engagement with standard hex socket tools provides reliable torque transmission for controlled installation.

Self-drilling point Drills and taps threads simultaneously, eliminating pilot hole drilling and reducing installation steps.

SUS410 stainless steel material Provides hardness for metal fastening applications with corrosion resistance for demanding outdoor environments.

Silver Dacromet surface treatment Offers high corrosion resistance with salt spray protection and a silver metallic aesthetic finish.

Application Scenarios

Roofing systems

Metal building cladding

Weatherproof enclosures

Structural steel connections

Outdoor metal assemblies

Heavy equipment mounting

Industrial roofing

Bridge and infrastructure

This hex head self-drilling screw with EPDM washer and 5# tail is deployed in outdoor and weather-exposed metal fastening applications requiring watertight sealing and enhanced drilling capability. Applications include roofing systems where weatherproof connections are essential, metal building cladding and enclosures, structural steel connections, outdoor metal assemblies, heavy equipment mounting, industrial roofing, and bridge and infrastructure projects where the EPDM washer provides sealing, the 5# tail offers enhanced penetration, and the silver Dacromet coating ensures long-term corrosion protection.

Common Questions and Solutions

What is the function of the EPDM washer?

The EPDM (ethylene propylene diene monomer) washer provides a watertight seal between the fastener head and the workpiece surface. This prevents moisture ingress through the fastener penetration point, making it suitable for outdoor and weather-exposed applications requiring weatherproof connections.

What is the 5# tail and what are its benefits?

The 5# tail refers to an extended drill point length that provides enhanced drilling capability for thicker material stacks. This allows the screw to penetrate heavier gauge substrates more efficiently than standard self-drilling points, reducing installation time and extending tool life.

What is the three-clawed thread design?

The three-clawed thread design incorporates a specialized thread geometry that provides improved engagement with the substrate material. This design enhances resistance to loosening from vibration and dynamic loads, making it suitable for structural and heavy-duty applications.

What material thickness can the ST5.5-24*50 screw accommodate?

The ST5.5-24 specification with 50mm length and 5# tail provides engagement for thicker material assemblies and heavier gauge substrates. The actual maximum material thickness depends on the drill point length and substrate hardness. Consult the technical datasheet for specific thickness recommendations.

Is this screw suitable for outdoor applications?

Yes. The SUS410 stainless steel material combined with silver Dacromet coating and EPDM washer provides corrosion resistance and weatherproof sealing for outdoor applications. The coating offers salt spray protection suitable for structural steel, roofing, and infrastructure projects exposed to weather conditions.

What is the recommended installation speed for this screw?

Install at controlled speeds to avoid overheating the extended drill point. The 5# tail requires appropriate speed management to maintain drilling efficiency. Use torque-controlled drivers to prevent over-tightening when the EPDM washer compresses against the workpiece surface without distorting the washer or sealing performance.

Installation Considerations

Select the correct hex socket size for the head to prevent rounding and ensure positive torque transmission during installation.

The 5# tail provides enhanced drilling capability for thicker materials. Adjust speed and feed rate accordingly to maximize drill point life and penetration efficiency.

Use torque-controlled installation tools to prevent over-driving. The EPDM washer should seal against the workpiece surface without being over-compressed or damaged.

Apply appropriate spindle speed based on material hardness; excessive speed may reduce drill point life and cause thermal damage to the EPDM washer or coating.

Ensure perpendicular alignment between screw axis and workpiece surface to prevent drill point deflection and ensure proper sealing of the EPDM washer.

The silver Dacromet coating provides corrosion resistance. Handle screws with clean gloves to maintain coating integrity and prevent contamination that could affect corrosion performance.