I. Application Fields & Product Standards

Manufactured in accordance with national standards for self-drilling screws, this screw features a hexagonal flange integrated with a waterproof rubber washer. It is specially designed for roof fastening in highly corrosive outdoor environments.

Widely applied to steel structure workshops, photovoltaic power station roofs, coastal color steel projects, outdoor guardrails and anti-corrosion curtain wall installation. Large volumes are exported year-round to building material markets in the Middle East, Southeast Asia and other coastal overseas regions.

The Dacromet anti-corrosion coating performs well in coastal saline-alkali, humid and rainy conditions. The extended shank fits the assembly of sandwich insulation panels and stacked multi-layer color steel sheets. Pre-drilling is not required, greatly shortening outdoor construction periods.

II. Raw Materials & Production Processes

Premium carbon steel is adopted as raw material and subject to overall quenching and tempering heat treatment. The drill tip meets standard hardness, resisting tip chipping and tail breakage when drilling thick steel plates.

The complete production workflow includes eleven procedures: raw material rough drawing, annealing, phosphating, fine drawing, cold heading, tail forming, thread rolling, thermal refining treatment, Dacromet anti-corrosion coating, washer assembly and packaging.

It adopts segmented thread design: the front section performs drilling while the rear section delivers stable fastening. The long shank bears force evenly and resists bending during tightening.

The Dacromet coating boasts strong adhesion without hydrogen embrittlement risks, and its salt spray resistance far exceeds conventional electro-galvanized products.

III. Core Product Advantages

Long-Lasting Anti-Corrosion Dacromet Coating

The dense coating resists acid, alkali and salt spray, providing long-term rust protection for coastal areas, chemical plants and rainy open-air environments, eliminating hidden dangers of roof water leakage caused by screw corrosion penetration.

Integrated Waterproof Sealing Structure

The EPDM composite rubber washer is UV-resistant and anti-aging, free from cracking under long-term sun exposure. It tightly seals the hole after tightening to fundamentally prevent roof water seepage.

Extended Segmented Thread Design

The extended shank fits multi-layer assembly of rock wool and polyurethane sandwich panels. Segmented threads avoid jacking up color steel sheets during locking, suitable for construction of thermal insulation roofs with various thicknesses.

IV. Quality Control, Warehousing & Supporting Services

All extended sizes are kept in permanent stock. Standard orders can be shipped within 48 hours. We accept full-container export orders and bulk orders for engineering projects.

Every batch undergoes item-by-item sampling inspection before delivery, covering drill tip hardness, Dacromet coating thickness, washer bonding strength and thread precision. Defective products with peeling coatings or damaged drill tips are fully screened out.

We can supply complete roof fastener sets matched with our short hex head self-drilling screws and countersunk self-drilling screws for one-stop sourcing. Custom self-drilling screws with special extended shanks and non-standard thread pitches can be produced per customer drawings. Stable production capacity guarantees long-term supply for large infrastructure projects.