Stainless Steel Built-in Expansion Bolts — M6 M8 M10 M12 | 201 / 304 / 316

Match the bolt diameter to your fixture's hole size and the load requirement. As a general guide: M6 (≈1/4") is typically used for light-duty brackets and shelving; M8 (≈5/16") suits medium loads like handrails and cable trays; M10 (≈3/8") handles heavier structural anchoring such as equipment frames; M12 (≈1/2") is generally chosen for heavy machinery bases and structural steel connections. Always drill a hole matching the bolt's nominal diameter and follow the embedment depth recommended for your base material.

Actual load capacity depends on the base material (concrete compressive strength, masonry type), embedment depth, edge distance, and spacing. In general, larger diameters and deeper embedment yield higher pull-out and shear values. For safety-critical applications, consult a structural engineer and reference anchor design standards such as ACI 318 Appendix D or ICC-ES reports. Do not rely on nominal diameter alone to estimate allowable loads.

316 stainless steel variants are generally recommended for outdoor coastal, marine, and salt-spray environments due to their molybdenum content, which provides superior resistance to chloride-induced pitting corrosion. 304 stainless steel is suitable for most outdoor applications away from direct salt exposure. 201 stainless steel is best reserved for dry or low-humidity indoor use where corrosion risk is minimal.

These bolts use ISO metric coarse threads per ISO 261 — the same standard used by the vast majority of metric fasteners worldwide. M6, M8, M10, and M12 are fully compatible with standard metric hex nuts, flat washers, and lock washers. They are not interchangeable with UNC or UNF inch-standard fasteners commonly found in older US construction hardware.

The 3-piece set includes the expansion bolt, expansion sleeve, and hex nut — everything needed for a standard installation into a clean, correctly sized hole. The 4-piece set adds a flat washer, which distributes the clamping load over a larger bearing area. Choose the 4-piece set when your fixture plate has a hole diameter noticeably larger than the bolt shank, or when you are fastening softer materials that could deform under the nut face alone.

Built-in expansion bolts generally perform well in solid brick and dense concrete block. Performance is typically reduced in hollow block, aerated concrete (AAC/autoclaved), or soft masonry because the expansion sleeve cannot develop full bearing contact. For hollow substrates, a sleeve anchor or chemical anchor is usually a better choice. Always perform a test installation and verify pull-out strength before committing to a full project.

1. Drill a hole matching the bolt's nominal diameter to the required embedment depth using a hammer drill and carbide-tipped bit. 2. Blow out all dust and debris with compressed air. 3. Insert the expansion bolt assembly into the hole. 4. Place your fixture over the protruding bolt, then add the washer (if included) and hex nut. 5. Tighten with a wrench — as the nut advances, the sleeve expands against the hole wall, creating a mechanical lock. Avoid over-torquing; follow the torque specification for the given diameter and base material to prevent cracking the substrate.