Tianjin Brisk Metalwork Co., Ltd. is one of the leading manufacturers and suppliers of black structural hollow section in China. We have world-leading production equipment and strong manufacturing capabilities. Please feel free to buy bulk durable black structural hollow section from our factory.
Product Overview
| Item | What We Supply |
|---|---|
| Section shapes | SHS, RHS, CHS |
| Production routes | Cold-formed welded (EN 10219 / ASTM A500 type), hot-finished (EN 10210 type) |
| Common grades | S235JRH, S275J0H/J2H, S355J0H/J2H, ASTM A500 Gr.B/C |
| Surface | Bare black, lightly oiled, clear-varnished |
| Lengths | 6 m and 12 m standard, cut-to-length on request |
| Processing | Saw cutting, drilling, end plates, bevelled ends |
| Documents | EN 10204 3.1 mill certificate, per-heat traceability |
Which Black Surface Should You Choose?
The surface condition decides how much preparation you do before welding or painting. We offer three options:
| Surface | What It Means | Best For |
|---|---|---|
| Bare black | Mill finish, no protective film | Immediate welding and blasting in a dry workshop |
| Lightly oiled | Thin oil film that slows surface rust | Stock held for weeks before fabrication |
| Clear varnished | Thin transparent lacquer | Longer storage or stock that will be seen before work starts |
Tell us how long the tubes will wait before use and what coating comes next, and we will recommend the film that suits both.
Does the Black Surface Affect Welding and Painting?
Yes, in two practical ways:
- Oil film: a light film is easy to burn off during welding, but it must be removed before painting or the coating may blister or peel. If your line blasts the tubes first, a light film is no problem.
- Mill scale: hot-finished sections carry a tight blue-grey mill scale that protects temporarily but is not a paint base. Shot-blasting to the cleanliness your paint system requires removes it. Cold-formed sections usually have a thinner, cleaner surface.
For galvanizing, tubes should be free of heavy oil and paint markings. We can supply with a minimal film to suit your galvanizer.
Black, Painted or Galvanized: Which Is Right?
| Option | Upfront Cost | Where It Fits |
|---|---|---|
| Black | Lowest | You blast and coat after fabrication; indoor frames |
| Factory-painted | Medium | Fast site turnaround, indoor or mild exposure |
| Hot-dip galvanized | Highest | Outdoor, coastal or long-life exposed structures |
Black wins when you control the coating process, because you apply protection after cutting and welding, so no coating is burned off or damaged at the joints.
How Do We Protect Black Tubes Before They Reach You?
Black steel rusts if it gets wet, and a light surface bloom can slow your blast line.
- Dry, covered storage before dispatch and tight bundling
- Waterproof wrapping and end protection on request
- Per-bundle marking with size, grade, heat number and quantity
- Straight, clean ends on cut-to-length orders, so welding starts without extra grinding
Case: 180 Tonnes of Black RHS and SHS for a Coating Shop
A structural fabricator was producing frames for three warehouse projects, using about 180 tonnes of black RHS and SHS in S355J2H, with wall from 4 to 8 mm.
The earlier supplier delivered heavily oiled tubes. Before each batch could enter the paint line, the shop had to degrease every piece, which added about two working days per lot and left some coatings with pinholes at the weld zones.
For the next order, we supplied the same grade with a light oil film suited to blasting, bundled and wrapped against moisture. The shop blasted and primed straight from the bundle, skipped the degreasing step, and finished the three projects without coating rework.
Typical Applications
- Warehouse, workshop and commercial steel frames
- Trusses, purlin supports and roof structures
- Mezzanines, platforms and stair frames
- Canopies, carports and gates
- Machinery bases and equipment frames
- Handrails and balustrade bases (coated after fabrication)
- Agricultural and livestock building frames
FAQ
Q: Is black hollow section the same steel as galvanized hollow section?
A: Yes. The base tube and its mechanical properties are the same; galvanizing is a coating added afterwards.
Q: Can I galvanize black hollow section after I fabricate it?
A: Yes. Add vent and drain holes in the design, and send the drawings if you want us to mark them.
Q: How long can black tubes be stored outdoors?
A: Black steel should be kept dry and covered. Light oil or varnish slows surface rust, but it is not a long-term outdoor protection.
Q: Do you provide mill certificates?
A: Yes. Every order comes with EN 10204 3.1 certificates linked to heat numbers, and 3.2 with third-party witnessing is available on request.
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