Product Overview 304 stainless steel hex washer head self-drilling screws (also known as A2 stainless steel Tek screws or self-drilling roofing screws) are premium-grade, corrosion-resistant fasteners designed for fastening metal roofing sheets, steel cladding, and lightweight steel structures to steel or timber substrates in the most demanding environments. The hexagonal washer head provides a large bearing surface and is driven with a standard hex socket, while the integrated EPDM-bonded sealing washer creates a watertight seal around the drilled hole. Unlike carbon steel alternatives, these screws are manufactured from AISI 304 (A2) austenitic stainless steel — the industry standard for corrosion resistance in coastal, marine, and high-humidity environments. The 304 stainless steel grade offers excellent resistance to rust and corrosion in harsh environments, making these screws ideal for Middle East coastal projects, marine installations, and Central Asian outdoor infrastructure where carbon steel fasteners would fail prematurely. These screws are manufactured to DIN 7504 K (hexagon washer head self-drilling screw) and ISO 15480 standards. The self-drilling point (Tek point) eliminates the need for pre-drilling — the screw drills its own pilot hole through steel sheets up to 12.5 mm thick, then forms a mating thread in the substrate. Available in diameters ST4.2, ST4.8, ST5.5, and ST6.3 mm, with lengths ranging from 13 mm to 150 mm. The 304 stainless steel construction provides superior corrosion resistance compared to zinc-plated or hot-dip galvanized carbon steel screws. 304 screws pass ≥720 hours neutral salt-spray (ASTM B117) testing, delivering a service life of 3–5 times that of ordinary carbon steel screws. This makes them the preferred choice for metal roofing, wall cladding, HVAC ductwork, solar panel mounting, and marine applications where long-term durability is critical. Standard & Compliance Parameter Specification Standard DIN 7504 K (hexagon washer head self-drilling screw); ISO 15480; ASME B18.6.4 Material AISI 304 (A2) austenitic stainless steel Tensile Strength 500–600 MPa (A2-70) Thread Type Self-drilling thread (ST), Type 17 point Head Type Hexagonal washer head with integrated EPDM sealing washer Finish Polished / passivated (natural stainless) Corrosion Resistance ≥720 hours neutral salt-spray (ASTM B117) Sealing Washer EPDM bonded washer (UV-resistant, temperature range −40 °C to +120 °C) Temperature Range −40 °C to +120 °C (washer); −200 °C to +400 °C (screw body) Drilling Capacity Up to 12.5 mm steel plate (depending on screw diameter) Size Range & Specifications Screw Size Diameter (mm) Standard Lengths (mm) Hex Drive Application ST4.2 4.2 13 / 16 / 19 / 25 / 32 7 mm Light roofing, cladding ST4.8 4.8 19 / 25 / 32 / 38 / 50 / 65 8 mm Standard roofing, HVAC ST5.5 5.5 25 / 32 / 38 / 50 / 65 / 75 8 mm Heavy roofing, steel cladding ST6.3 6.3 25 / 32 / 38 / 50 / 65 / 75 / 100 / 125 / 150 8 mm / 10 mm Heavy-duty roofing, structural connections Custom lengths and diameters available upon request. Product Features AISI 304 (A2) Stainless Steel Construction — Provides excellent corrosion resistance in coastal, marine, and high-humidity environments. Passes ≥720 hours neutral salt-spray testing (ASTM B117) and offers a service life 3–5 times longer than carbon steel alternatives. Self-Drilling Point (Tek Point) — The hardened drill point penetrates steel sheets up to 12.5 mm thick without pre-drilling, reducing installation time and labor costs. Hex Washer Head — Large bearing surface distributes clamping force evenly and prevents damage to roofing sheets. Compatible with standard hex socket drivers. EPDM-Bonded Sealing Washer — The UV-resistant EPDM washer compresses against the roofing sheet to create a watertight seal, preventing water ingress at the fastener penetration point. Superior Holding Force — High toughness and holding force prevent loosening over time, even under vibration and thermal cycling. Wide Range of Sizes — Diameters from ST4.2 to ST6.3 mm, lengths from 13 mm to 150 mm, covering virtually all roofing, cladding, and marine fastening requirements. Eco-Friendly Finish — Natural stainless finish eliminates the need for zinc plating or coatings, avoiding hexavalent chromium concerns and supporting sustainability goals in Middle East construction projects. Applications 304 stainless steel hex washer head self-drilling screws are widely used in: Metal Roofing Installation — Fastening corrugated and trapezoidal steel roofing sheets to purlins, rafters, and steel frames in coastal and high-humidity environments. Wall Cladding — Attaching metal wall panels, sandwich panels, and composite cladding to steel or timber structures. Marine & Offshore — Deck fastening, dock structures, and offshore platform applications where saltwater corrosion is a concern. Solar Panel Mounting — Fastening mounting rails and brackets to roof structures in solar energy installations. HVAC Ductwork — Securing duct insulation, hangers, and flashing in commercial and industrial buildings. Oil & Gas Facilities — Corrosion-resistant fastening in petrochemical plants and refinery infrastructure. Agricultural Buildings — Poultry houses, barns, and storage facilities where moisture and ammonia exposure demand superior corrosion resistance. Installation Guidelines Select the correct screw length — The screw should penetrate the substrate by at least 25 mm beyond the total thickness of the material being fastened. Use a variable-speed screwdriver — Drive at low speed (1,500–2,500 RPM) with steady pressure until the EPDM washer compresses slightly against the roofing sheet. Do not over-tighten — Excessive torque will compress the EPDM washer beyond its elastic limit and cause water leakage or damage to the roofing sheet. Drive perpendicular to the surface — Angled installation prevents the washer from seating properly and creates an incomplete seal. Inspect after installation — Check that all washers are properly compressed and no screws are over-driven or protruding. Use stainless steel drivers — To avoid galvanic corrosion, use stainless steel or non-metallic hex drivers. Do not mix stainless steel screws with carbon steel washers or components in corrosive environments. Quality Assurance All screws are manufactured under strict quality control and can be supplied with: Mill Certificates — material test reports with chemical composition and mechanical properties (AISI 304 verification) Salt spray test reports — ≥720 hours neutral salt-spray (ASTM B117) verification Drilling capacity test reports — verification of drilling performance Torque test reports — verification of torsional strength Third-party inspection reports (SGS, BV, TÜV) — available upon request EN 10204 3.1 Inspection Certificates — available upon request Ordering Information To place an order or request a quotation, please provide: Screw size (ST4.2, ST4.8, ST5.5, ST6.3 mm) Length(s) required Quantity per size Certification requirements Packaging preferences