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Help CenterSquare Steel & Square Steel Pipe,Q235B、Q345B（Q355B）、Q195、16Mn、45#
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Square Steel Pipe Product Detailed Description
1. Product Definition and Classification
Definition
Square steel pipe is a hollow steel material with a square or rectangular cross-section. It is formed from hot-rolled or cold-rolled steel coils or steel billets through bending forming, welding or seamless rolling processes, featuring high strength, light weight and easy processing, widely used in construction, machinery, municipal engineering and other fields.
Core Classification
By Production Process
Welded Square Pipe: High-frequency straight seam welding and submerged arc welding. It has low cost and high mass production efficiency, suitable for general structural use.
Seamless Square Pipe: Manufactured by hot rolling and cold drawing seamless technology, with no weld seam and high pressure resistance, applied in high-pressure and heavy-load scenarios.
By Material Carbon Steel
Q235B, Q345B (Q355B), Q195. As mainstream materials for construction and machinery, they own high cost performance.Alloy steel: 16Mn, 45#. Featured with high strength and wear resistance, used in machinery manufacturing and heavy equipment.
By Surface Treatment
Hot-dip Galvanized: Zinc coating thickness 50-150μm, excellent rust resistance, the preferred choice for outdoor and coastal projects.
Electro-galvanized: Thin coating of 5-15μm with high precision, applied to indoor decoration and light structure.
Spray Paint / Plastic Spraying: Integrated anti-corrosion and decorative effect with customizable colors, commonly used in municipal engineering and furniture manufacturing.
Black Uncoated Pipe: Without surface treatment, used for internal structures or secondary processing.
2. Specification Parameters (National Standard System)
Dimension Representation
Square pipe: Side Length (mm) × Wall Thickness (mm), e.g. 100×100×3.0
Rectangular pipe: Length × Width × Wall Thickness (mm), e.g. 80×40×2.5
Standard length: 6m / 9m / 12m, customized cutting available with tolerance ±5mm.
Common Specification Range
Side length: 10mm–600mm; Wall thickness: 0.8mm–30mm.Non-standard customization is available for special side length, wall thickness and special-shaped cross-section according to drawings.
Executive Standards
Cold-formed hollow structural steel: GB/T 6728-2017
Cold drawn special-shaped steel pipe: GB/T 3094-2012
Welded steel pipe for low-pressure fluid transportation: GB/T 3091-2015
3. Main Material and Mechanical Properties
Mechanical Performance of Common Materials
| Material | Yield Strength (MPa) | Tensile Strength (MPa) | Elongation (%) | Application |
|---|---|---|---|---|
| Q235B | ≥235 | 375-500 | ≥26 | Building frame, guardrail, general structure |
| Q345B(Q355B) | ≥345(355) | 470-630 | ≥21 | Factory beam and column, bridge, heavy machinery |
Product Performance Advantages
Light Weight: 30%-40% lighter than solid steel with the same cross-section, reducing structural self-weight and overall cost.
Excellent Mechanical Property: Square cross-section owns strong bending resistance, torsion resistance and compression stability, better than round pipe of the same specification.
Easy Processing: Support cutting, welding, drilling and bending, adapting to complex structure and installation requirements.
Corrosion Resistance: Galvanized, painted and plastic sprayed surface treatment adapts to humid, acid-base and harsh outdoor environments.
4. Brief Production Process
Welded Square Pipe
Steel coil uncoiling → leveling → shearing → bending forming → high-frequency welding → deburring → fixed length cutting → surface treatment → inspection and warehousing.
Seamless Square Pipe
Round pipe billet → heating → perforation → hot rolling / cold drawing → sizing → straightening → fixed length cutting → surface treatment → inspection and warehousing.
5. Application Scope
Construction Engineering: Steel structure beam and column, truss, curtain wall keel, stair handrail, scaffold.
Mechanical Manufacturing: Equipment frame, conveyor guide rail, machine tool base, structural parts of automobile and agricultural machinery.
Municipal Engineering: Street light pole, traffic signal frame, guardrail, bridge support, landscape facilities.
Petrochemical Industry: Low-pressure fluid conveying pipe, support for chemical equipment.
Decoration Engineering: Indoor and outdoor decorative lines, furniture frame.
6. Quality Control and Acceptance Standard
Dimensional Tolerance: Side length ±0.5mm, wall thickness ±0.1mm, length ±5mm in accordance with national standard.
Visual Inspection: No surface crack, obvious rust or burr; smooth weld seam for welded pipe.
Mechanical Test: Sampling inspection for tensile, bending and impact test per batch to ensure performance compliance.
Material Certificate: Provide material test report, product certificate and inspection report with traceable production batch.
7. Selection Suggestion
Load Priority: Choose seamless pipe for heavy load and high pressure; choose welded pipe for general structure with high cost performance.
Environment Adaptation: Select hot-dip galvanized pipe for outdoor and coastal use.
Specification Matching: Confirm cross-section and wall thickness according to load calculation, prefer national standard specifications to control cost.
Length Optimization: Adopt standard fixed length of 6m/9m/12m to reduce cutting loss and improve installation efficiency.
8. Packaging and Transportation
Packaging: Bundled bare pipe, 2-5 tons per bundle. Galvanized pipes are wrapped with plastic film and woven bags at both ends for moisture proof.
Transportation: Delivered by truck or railway; avoid direct sunlight, rain and collision to keep products intact.
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