Main Specifications of Galvanized Square Tubes
1. Cross-Sectional Dimensions (Side Length)
Common specifications (unit: mm): 20×20, 25×25, 30×30, 40×40, 50×50, 60×60, 80×80, 100×100, 120×120, 150×150, etc.
Common rectangular tube specifications: 40×20, 50×25, 60×30, 80×40, 100×50, 120×60, etc.
A wide range of sizes is available and can be customized as needed.
2. Wall Thickness
Common range: 0.8mm to 5.0mm.
Often referred to colloquially by thickness, e.g., "1.2 thick", "2.0 thick", "3.0 thick".
The main difference between National Standard (GB) and Non-Standard (Market Standard) tubes lies in the wall thickness. GB tubes have full, guaranteed wall thickness and higher load-bearing capacity; non-standard tubes typically have actual wall thickness less than the nominal value and are lower in price.
3. Material
Q235: The most commonly used ordinary carbon structural steel, offering good strength and weldability, suitable for most structures.
Q195: Slightly lower strength, used for lightly loaded structures.
Q345: High-strength low-alloy steel, used for applications requiring higher load-bearing capacity.
Zinc Coating: Divided into electro-galvanized (cold galvanized) and hot-dip galvanized.
Hot-Dip Galvanized Square Tube: Thick zinc layer (usually >60μm), excellent corrosion resistance, can last 20-50 years outdoors. The surface has a spangle pattern and is slightly rough.
Electro-Galvanized Square Tube: Thin zinc layer, smooth and aesthetically pleasing surface, but weaker corrosion resistance, mostly used for indoor dry environments.
Length
Typically 6 meters per piece, can also be custom-cut to length.
Product Manufacturing Process Types
1. "Fabricated then Galvanized" Tube
Process: Steel sheet/strip is first cold-formed and welded into a square tube, then the entire tube undergoes hot-dip galvanizing.
Advantages: Uniform zinc coating on both internal and external walls, providing comprehensive corrosion protection. Especially suitable for structures exposed to humid environments.
Disadvantages: Zinc dross may form at the weld seam during galvanizing, which can affect precision for certain connection types.
2. "Galvanized then Fabricated" Tube
Process: Uses pre-galvanized steel sheet/strip, which is directly cold-formed and welded into shape.
Advantages: Smooth, aesthetically pleasing surface, flexible production, suitable for thin-walled tubes.
Disadvantages: The weld seam lacks zinc coating protection, making it the weak point for corrosion. Rusting often begins at the weld.
Main Application Fields
1. Construction & Steel Structure (Largest Market)
Primary Steel Structure: Columns, beams, purlins for lightweight factories, warehouses, logistics centers, agricultural markets.
Enclosure & Decoration: Wall studs for building exteriors, roof supports, canopy frames, balcony railings, stair handrails, security window grilles, louvre window frames.
Construction Sites: Scaffolding (main components of cuplock scaffolding), construction guardrails, temporary support frames.
2. Infrastructure & Municipal Engineering
Road Facilities: Traffic signposts, street light poles, guardrails, barrier posts.
Municipal Facilities: Framework for bus shelters, public bicycle sheds, waste sorting stations, toll booths.
Telecommunications & Power: Simple signal towers, cable trays, utility poles.
3. Machinery Manufacturing & Industrial Equipment
Equipment Frames: Frames and protective covers for various machine tools, conveyors, automated equipment, production line workbenches, inspection equipment.
Storage & Logistics: Heavy-duty racking, material shelves, storage cages, pallet feet.
Agricultural Greenhouses: Main and secondary framework for modern agricultural greenhouses, offering good corrosion resistance.
4. Home Furniture & Daily Use
Outdoor Furniture: Frames for park benches, beach chairs, patio tables and chairs, swings.
Indoor Furniture: Industrial-style bookshelves, racks, TV stands, table legs, bed frames.
Display Props: Framework for shop display cabinets, display stands, promotional racks.
5. Other Specialized Fields
Automotive Industry: Support structures inside vehicle compartments, auxiliary chassis components.
Ship Cabins: Support structures for internal partitions and furniture (requires specific marine-grade galvanized tubes).
Selection Guidelines
1. Define the Usage Environment:
Outdoor, humid, dusty environments: Must use hot-dip galvanized square tubes, and the thicker the zinc layer, the better.
Indoor dry environments: Electro-galvanized square tubes or cheaper black steel tubes (ungalvanized, require painting for rust prevention) can be used.
2. Load-Bearing & Safety:
For load-bearing structures (e.g., racking, shed beams), pay close attention to wall thickness and material strength. Prioritize National Standard (GB) tubes and perform mechanical calculations.
For non-load-bearing decorative purposes (e.g., trim), thin-walled tubes can be chosen to save costs.
3. Processing Requirements:
If significant welding is required later, note that the zinc coating emits toxic fumes at high temperatures. Operate in a well-ventilated area, and apply anti-corrosion paint to the welded seams afterward.
For high-precision assembly, be aware that hot-dip galvanized tubes may have slight deformation or uneven zinc coating.
Hot Tags: 20*20 galvanized steel pipes, China 20*20 galvanized steel pipes manufacturers, suppliers, factory