Carbon Steel Rectangular Tube

Tianjin BRISK STEEL is one of the manufacturers of carbon steel rectangular tube in China. Our products are mainly exported to the Middle East, Southeast Asia, Europe, New Zealand, and other regions.If you would like to learn more about our products, feel free to contact us and send your purchase list.

 SURFACE TREATMENT

Tianjin BRISK STEEL focus on produce and supply hollow section and steel pipe

• The surface treatment commonly used for square and rectangular tubes directly determines their rust resistance, appearance, cost, and service life. 

• Black Tubes:
  Process: Cold formed / No surface treatment after welding, retaining the original color of the steel
  Appearance: Grayish-black, with oxide scale
  Features: Cheapest, easy to process
  Disadvantages: Extremely prone to rusting, only suitable for short-term indoor use

• Hot-dip galvanizing (Hot-dip zinc plating) – Most commonly used for outdoor applications:

  Process: Square tubing is immersed in high-temperature molten zinc, forming an alloy layer between zinc and steel.

  Appearance: Silver-gray with zinc bloom on the surface.

  Features: Extremely strong corrosion resistance; suitable for outdoor use for 10–30 years. Thick coating, impact-resistant, and resistant to acids, alkalis, and rainwater.

  Applications: Outdoor railings, awnings, curtain wall framing; greenhouses, streetlight poles, steel structures, factory frames; ideal for coastal, humid, and corrosive environments.

• Electro-galvanizing (Pre - galvanizing):

  Process: Electrolytically depositing a thin zinc layer

  Appearance: Bright silver, attractive but the coating is very thin

  Features: Lower cost than hot-dip galvanizing, Most rust-resistant, prone to rusting outdoors

  Applications: Indoor decoration, furniture, display racks
  Suitable for applications requiring light rust prevention and a bright appearance

• Spray painting:

  Process: Rust removal → Primer → Topcoat/Powder high-temperature curing

  Appearance: Colors can be customized (black, white, gray, blue, etc.)

  Features: Beautiful and highly decorative; Moderate rust resistance, susceptible to scratches

  Applications: Indoor shelves, railings, doors and windows; Architectural decoration, landscaping

• Oil coating:

  Process: Rust removal, phosphating, sealing, and rust-preventive oil application

  Appearance: Natural metallic color with an oily feel

  Features: Short-term rust prevention

  Applications: Temporary protection before factory processing, inventory protection

• The anti-corrosion ability level is as follows:

  Black tubes<Oil coating<Spray painting<Pre galvanizing<Hot dip galvanizing

Process Type:  ERW/ SMLS

1. Erw cold-formed square and rectangular tubes (95% market usage)

2. Seamless round-to-square conversion process (seamless square and rectangular tubes)

• Large square tubes with wall thicknesses greater than 16mm are difficult to weld into shape using steel strips. They are generally made by cold drawing seamless round tubes into square shapes.
• Or it may be used in harsh environments, such as pressurized conditions, explosion-proof conditions, heavy-duty vibration, precision machinery, or where welding is strictly prohibited.

• Square/rectangular cross-section: Easier to splice, screw-fix, and weld than round tubes.
• Uneven stress distribution: Strong resistance to bending, torsion, and compression.
• Easy construction: Simple to cut, drill, weld, and paint.
• High cost-performance ratio: High-frequency welded square and rectangular tubes are inexpensive and readily available