Channel Nuts for Seismic Bracing

I. Classification & Names

1. Channel Spring Nut (Clip Nut / Sliding Nut)

Compatible with 41-series seismic C-channel steel (41×41, 41×62, 41×82). Fitted with integrated spring clips, it can be inserted freely into any position inside the channel slot for sliding positioning, without pre-welding or pre-drilling.

• Application: Connect seismic hinges, diagonal braces, pipe clamps, connectors and cross arms

• Sizes: M8, M10, M12 (M10 & M12 are mainstream for seismic projects)

• Material: Q235 carbon steel; surface finishes: electro-galvanized, hot-dip galvanized, Dacromet

  
  

2. Channel Self-Locking Nut (Anti-Loosening Nut)

Available in nylon insert lock nuts and all-metal lock nuts. Used together with suspender rods and channel clamp plates to bear vertical loads. Anti-loosening performance is mandatory per seismic codes.

• Matching scenario: Secure cross arms by running suspender rods through channel steel and channel clamp plates, locked from top and bottom

• Sizes: M10, M12

• Advantages: Resists loosening under reciprocating seismic vibration, compliant with GB 50981 seismic standard

3. Standard Hex Nut (Auxiliary Only, Not for Independent Seismic Load Bearing)

Only used together with flat washers. Not allowed for standalone use at force-bearing seismic joints, and single use is not accepted in project inspection.

II. Detailed Introduction to Two Core Nut Types

(1) Channel Spring Nut (Sliding Clip Nut)

• Structure: Hex nut plus stainless steel elastic retaining clip

• Operation: Insert into the channel slot from the end of C-channel steel; slide freely to the required position. The spring clip clamps tightly after release to prevent falling off, then fasten fittings with bolts directly.

• Matching fittings: Seismic hinge connectors, pipe clamps, lateral & longitudinal brace connectors, cable tray clamps

• Selection Tips

• Small fire pipelines & cable trays: M10 spring nuts

• Large air ducts & heavy-duty seismic supports for pipelines above DN200: M12 spring nuts

(2) Seismic Self-Locking Nut (Load-Bearing Nut for Suspender Rods)

• Assembly combination: Full-threaded suspender rod + flat washer + upper channel clamp plate + C-channel steel + lower channel clamp plate + flat washer + self-locking nut

• Installation requirement: One self-locking nut shall be fitted on both top and bottom of each suspender rod to clamp the channel clamp plates; sole use of standard hex nuts is prohibited.

• Specified tightening torque (code requirement)

• M10 self-locking nut: 35 N·m

• M12 self-locking nut: 50 N·m

III. Anti-Corrosion Surface Treatments (Selected by Working Environment)

• Electro-galvanized: Cost-effective, for dry indoor shopping malls and office buildings

• Hot-dip galvanized: High anti-corrosion performance, preferred for mechanical & electrical seismic systems; suitable for basements, underground pipe galleries, humid parking lots and outdoor areas

• Dacromet coating: Superior rust resistance for chemical plants and humid acid-alkali workshops

IV. Standard On-Site Assembly Combinations

Vertical Hanging Load-Bearing Assembly

Full-threaded suspender rod + flat washer + upper channel clamp plate + C-channel steel + lower channel clamp plate + flat washer + self-locking nut

Lateral / Longitudinal Diagonal Brace Connection Assembly

Channel spring nut + bolt + seismic hinge / diagonal brace connector

V. Key Inspection Acceptance Criteria

1. Standard hex nuts alone are forbidden at all force-bearing seismic joints; self-locking anti-loosening nuts must be adopted.

2. Channel spring nuts must be used for slidable diagonal brace connections to facilitate on-site dimension adjustment.

3. Complete galvanized coating without burrs, smooth threads and no thread stripping are required.

4. All fittings shall adopt hot-dip galvanized finish for buildings with seismic fortification intensity of Grade 6 and above.