Square & Rectangular Black Steel Tube is a high-quality carbon steel hollow section with a black surface finish, manufactured through advanced welding processes such as ERW (Electric Resistance Welding). It features high strength, excellent weldability, accurate dimensions and reliable structural performance, making it widely used in construction, steel structures, machinery manufacturing and industrial applications. As a professional black steel tube manufacturer and supplier, we provide square and rectangular black steel tubes in various sizes, wall thicknesses and lengths. Our products are available in different steel grades, including Q195, Q235, Q345, ASTM A500, S235JR, S355JR and other equivalent materials. All products are manufactured according to international standards such as ASTM, EN, DIN, JIS, GB, ISO and BS. Black square and rectangular steel tubes are commonly used as structural components due to their excellent load-bearing capacity and stable performance. Compared with galvanized tubes, black steel tubes have a natural mill finish and are suitable for applications where additional painting, coating or surface treatment will be applied after fabrication. Our products are widely used in building structures, steel frames, machinery, agricultural equipment, greenhouse structures, fencing, scaffolding, transportation facilities and general industrial projects. We offer customized solutions with different dimensions, thicknesses, lengths and packaging options according to customer requirements. With strict quality control, advanced production facilities and professional export experience, we supply reliable square and rectangular black steel tube solutions for customers worldwide.







■ Product Parameters
Item | Specification |
Product Name | Square & Rectangular Black Steel Tube |
Material | Q195, Q215, Q235, Q275, Q355, ASTM A36, SS400, S235JR, S275JR, S355JR, etc. |
Production Process | High Frequency ERW Welded |
Shape | Square / Rectangular |
Standard | ASTM A500, ASTM A53, EN10219, EN10210, JIS G3466, GB/T 6728, AS/NZS 1163, etc. |
Outer Size | Square: 10×10mm–500×500mmRectangular: 20×10mm–600×400mm |
Wall Thickness | 0.6mm–25mm |
Length | 5.8m, 6m, 9m, 12m, or as customer's requirement |
Surface | Black, Oiled, Anti-rust Coating |
End Type | Plain End, Beveled End |
Packing | In bundles with steel strips, waterproof package, or as customer's requirement |
Inspection | Chemical Composition, Mechanical Properties, Dimensional Inspection, Hydrostatic Test, NDT (if required) |
Certificate | ISO 9001, CE, SGS, BV, MTC EN10204 3.1 |
Application | Building Structure, Steel Structure, Machinery Manufacturing, Fence, Greenhouse, Furniture, Warehouse, Bridge Construction, Agricultural Equipment, Infrastructure Engineering |
MOQ | 5 Tons (Negotiable) |
Trade Terms | EXW, FOB, CFR, CIF |
Payment Terms | T/T, L/C at Sight |
Delivery Time | Usually 7–25 Days After Deposit |
Supply Capacity | 5,000–10,000 Tons per Month |
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■ FAQ
Q: Are you a trading company or a manufacturer ?
A: We are manufacturer. Every month, we do a procurement for a massive number of steel material from Chinese state owned mill. The total value of steel processing equipment is more than 30 million dollars. Our major products cover all category of steel industry, and it is totally compatible to all kind of world steel standard.
Q: Do you have large amount of steel products in stock ?
A: Yes, we do. In large-scale indoor warehouses, the total stock value is over 150 millions dollar.
Q: Do you provide the samples ? Free or Extra ?
A: It is free, depend on the value of the sample. The cost of the freight would be charge.
Q: How long is the delivery time ?
A: Officially, it is within 7 days. Actually, we can deliver within 3 days. Customized products or non-standard size products would be taken 10-30 days to deliver, depend on the production cycle. Generally, most of the products finished and delivered within 20 days.
Q: Do you accept the third party inspection ?
A: Absolutely yes!
Q: How could you guarantee your products ?
A: Each batch of products must have its own factory inspection report. If the third-party inspection report of the product you purchased does not match our factory inspection report, we will resend the goods, and we will carry all the costs by ourselves.
Q: How can I get your quotation as soon as possible ?
A: You may have many methods to contact us. Email and fax will be checked within 12 hours, and Skype, WeChat and WhatsApp will be online in 24/7. Please send us your requirement, attaching specification (Steel grade, dimension, quantity, destination port) or any you are concerned, you will obtain a competitive price and supply solution soon.
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