Square U-Bolts Stainless Steel — M6 to M24 | 304 A2 & 316 A4 Marine Grade

Match the thread diameter (M6, M8, M10, M12, M16, M20, M24) to your nut and plate requirements, then select a leg length that spans your pipe or bar plus the mounting plate thickness. For example, an M8 x 38mm (≈1.5") U-bolt typically suits 25–32mm OD pipe. When in doubt, size up — a slightly longer leg can always be accommodated with extra nuts.

304 (A2) is a general-purpose stainless steel suitable for most indoor and sheltered outdoor applications. 316 (A4) adds molybdenum, giving it significantly better resistance to chlorides, salt spray, and harsh chemicals — making it the preferred choice for marine, coastal, and chemical-processing environments. If your installation is within a few miles of the ocean or exposed to road salt, choose A4.

Yes. The 316 A4 Marine Grade variants are specifically designed for saltwater and coastal exposure. For general outdoor use in non-coastal areas, 304 A2 is generally sufficient. Both grades are corrosion-resistant and will not rust under typical outdoor conditions when properly installed.

These square U-bolts use standard ISO metric coarse threads (M6, M8, M10, M12, M16, M20, M24), compatible with standard metric nuts and washers. They are not compatible with UNC/UNF inch threads. If you are replacing existing U-bolts, verify the thread pitch with a thread gauge before ordering.

Load capacity depends on thread size, material grade, and installation torque. Generally, larger diameters (M12 and above) handle significantly higher clamping loads. Per ISO 3506, A2-70 and A4-70 stainless fasteners typically have a minimum tensile strength of 700 MPa. For structural or safety-critical applications, consult an engineer and refer to the relevant ISO 3506 tensile data for your specific size.

Square U-bolts are commonly used to clamp round pipes, conduit, and tubing to flat surfaces or structural members. Typical applications include pipe support bracket installations in plumbing and HVAC systems, exhaust pipe clamps, antenna and satellite dish mounts, trailer axle U-bolt replacement, marine rigging hardware, and custom metal fabrication projects.

The listing quantity refers to the number of U-bolt bodies (1, 2, or 5 pieces depending on the variant selected). Matching metric nuts and washers are sold separately. We recommend using stainless steel nuts of the same grade (A2 or A4) for best corrosion compatibility and to avoid galvanic issues.

Divide the millimeter value by 25.4 to get inches. Quick reference: 25mm ≈ 1", 50mm ≈ 2", 100mm ≈ 3.9", 150mm ≈ 5.9", 300mm ≈ 11.8", 480mm ≈ 18.9". All size options in the variant selector show both the thread diameter and leg length in mm.