Seismic bracing for air ducts

I. Performance Characteristics

1. Strong Seismic Protection Capability

- Utilizes Q235B high-strength steel or aluminum alloy material, combined with articulated, spring damping, and other seismic joint designs, capable of absorbing horizontal and vertical impact forces during earthquakes, reducing the risk of duct displacement and detachment.

- Complies with GB 50981 "Code for Seismic Design of Mechanical and Electrical Engineering in Buildings," able to withstand seismic loads with horizontal acceleration ≥0.6g, suitable for seismic fortification intensity zones of 6-9 degrees.

2. High Load-Bearing Capacity and Stability

- Single bracket load-bearing capacity ranges from 100-1000kg depending on specifications. Through triangular stable structures or multi-directional support designs, it prevents duct twisting and overturning due to vibrations, ensuring continuous system operation during earthquakes.

3. Flexible Adaptation and Compatibility

- Compatible with rectangular ducts (side length ≥250mm) and circular ducts (diameter ≥500mm). Spacing and height can be adjusted using U-clamps, pipe clamps, and other accessories, accommodating ducts of different sizes.

- Can share base supports with cable trays, pipelines, and other mechanical and electrical seismic brackets, saving installation space and costs. Suitable for factories, hospitals, subways, and other multi-scenario applications.

4. Corrosion Resistance and Durability

- Surface treated with hot-dip galvanizing (zinc layer thickness ≥65μm), epoxy spraying, or zinc-aluminum-magnesium coating, resistant to moisture, salt spray, and chemical corrosion. Outdoor service life exceeds 20 years, with long maintenance intervals indoors.

II. Technical Parameters

Parameter Type Specific Indicators

Material Q235B steel, aluminum alloy 6061-T6, tensile strength ≥375MPa, yield strength ≥235MPa

Surface Treatment Hot-dip galvanizing (zinc layer thickness ≥65μm), epoxy zinc-rich paint (dry film thickness ≥80μm), zinc-aluminum-magnesium coating (salt spray resistance ≥1000h)

Load-Bearing Range Single bracket conventional load-bearing 100-1000kg, customizable for extra-large load brackets (e.g., for large-diameter ducts)

Seismic Joint Types Articulated, universal ball joint, spring damping type, horizontal displacement compensation ≥50mm, vertical displacement compensation ≥20mm

Installation Spacing - Horizontal ducts: spacing ≤9m for 6-7 degree fortification, spacing ≤6m for 8-9 degree fortification - Vertical ducts: spacing ≤4m, at least one support per floor

Applicable Duct Specifications Rectangular duct side length ≥250mm, circular duct diameter ≥500mm, special specifications customizable

III. Usage Instructions

1. Installation Process

- Positioning and Marking: Based on design drawings, use a level and tape measure to determine bracket installation positions, ensuring horizontal duct bracket spacing meets seismic fortification requirements (e.g., spacing ≤6m for 8-degree fortification zones), with at least one vertical duct bracket per floor.

- Fixing the Base: Use expansion bolts (M12 and above) to fix the base on concrete walls/floors; use welding or bolt connections on steel structures, ensuring the base load-bearing capacity is ≥1.5 times the bracket load.

- Assembling the Bracket Main Body: Assemble channel steel, seismic connectors, and pipe clamps according to the drawings. Adjust bracket height and angle to ensure the duct centerline is perpendicular to the bracket, and tighten joints with bolts (torque ≥45N·m).

- Installing and Securing the Duct: Place the duct on the bracket and secure it with U-clamps or pipe clamps, ensuring no looseness at connections. Articulated parts of seismic joints should move freely without affecting duct thermal expansion and contraction.

2. Maintenance Points

- Regular Inspection: Every six months, check for loose connectors, cracked welds, and damaged surface anti-corrosion layers. Replace bolts or repaint as needed.

- Seismic Joint Maintenance: For spring damping joints, apply lubricant annually to prevent rust. Test spring elasticity (rebound after compression should be ≥90%).

- Duct System Inspection: During duct system maintenance, check if brackets and duct fasteners have shifted due to vibrations, ensuring no gaps between pipe clamps and ducts.

3. Precautions

- Standard Compliance: Seismic brackets must be designed according to GB 50981. Additional brackets with flexible joints are required on both sides of building expansion joints and settlement joints.

- Fire Safety Requirements: Bracket materials must be non-combustible. Components in contact with fire-rated ducts must have fire certification (e.g., GB 8624-B1 grade).

- Load Calculation: Before installation, calculate duct weight (including internal medium) + bracket self-weight, ensuring bracket load-bearing capacity ≥1.2 times the actual load to avoid overload deformation.

IV. Selection Reference

- By Seismic Fortification Intensity:

- 6-7 Degree Fortification: Use standard articulated brackets with horizontal spacing ≤9m;

- 8-9 Degree Fortification: Use spring damping brackets with horizontal spacing ≤6m and vertical spacing ≤4m.

- By Duct Size:

- Rectangular Duct (630mm×320mm): Use brackets with load-bearing ≥300kg, paired with 40×40mm channel steel;

- Circular Duct (Diameter 800mm): Use brackets with load-bearing ≥500kg, secured with ring pipe clamps.

Through the above performance parameters and usage specifications, duct seismic brackets ensure the stability of ventilation systems during earthquakes, reducing post-disaster equipment damage and secondary disaster risks, making them key components in mechanical and electrical seismic engineering.