Stainless Steel Square & Rectangular Tubes

• ​Introduction

Stainless steel square and rectangular tubes are hollow structural products with square or rectangular cross-sections, made of stainless steel materials. They combine the excellent corrosion resistance, high strength, and aesthetic appearance of stainless steel, making them widely used in various industrial, architectural, and decorative fields. Compared with traditional round tubes, they have a larger contact area and more stable structural performance, which can better meet the needs of different engineering designs.

• ​Main Functions

Structural support: It can be used as load-bearing components in buildings, bridges, machinery, etc., to withstand pressure, tension, and torque, ensuring the stability and safety of the overall structure.

Fluid transportation: Due to its good corrosion resistance, it is suitable for transporting various fluids such as water, oil, gas, and chemical media, preventing leakage and pollution caused by material corrosion.

Decorative application: With a smooth surface and beautiful appearance, it is often used in architectural decoration, such as handrails, guardrails, door and window frames, to enhance the aesthetic sense of the environment.

• ​Tubing Standards

ASTM A554, ASTM A269 ; EN 10217-7； GB/T 12771，GB/T 3094.

• ​Material & Performance

304/304L，316/316L，430 etc. 1.4301/1.4306,1.4401/1.4404, 1.4016 etc.

The commonly used materials are 304, 304L, 316,430 stainless steel, etc. 304 stainless – steel has good comprehensive performance, with excellent corrosion resistance and formability, and can resist the corrosion of most organic acids and inorganic acids. 316 stainless – steel has better corrosion resistance than 304, especially in chloride – containing environments, and is often used in occasions with higher corrosion – resistance requirements. These stainless – steel materials have high strength, good toughness, and can maintain stable performance in a certain temperature range.430 stainless steel is a type of ferritic stainless steel. It has good corrosion resistance and oxidation resistance, and its price is relatively low. It is often used in architectural decoration parts that do not require high strength, such as decorative panels.Commonly used stainless steel has good ductility, which is convenient for cold working, bending, welding and other processing operations, and can be processed into Square and rectangular tubes in various sizes.

• ​Manufacturing Process

Raw Material Preparation：Select standard-compliant stainless steel strips or coils (e.g., 304, 316), cut them into strips of appropriate width based on tube specifications, and remove surface impurities.

Round Tube Blank Forming：The stainless steel strip is continuously rolled by a cold roll forming machine, gradually bending into an open round tube blank.

Welding into Round Tube：Using high-frequency welding, the seam of the open round blank is fused to form a closed round stainless steel tube.

Rolling Round Tube into Square/Rectangular Shape：The closed round tube is fed into forming dies (square/rectangular roll sets), gradually deformed into a square or rectangular cross-section through continuous extrusion, stretching, and rolling, with dimensional accuracy (e.g., side length, wall thickness) controlled.

Annealing：The formed square/rectangular tube undergoes annealing: heated to a specific temperature and slowly cooled to relieve internal stress from welding and rolling, improving mechanical properties and corrosion resistance.

Cooling and Straightening：After annealing, it is cooled to room temperature via water to prevent deformation; then straightened by a straightening machine to ensure straightness meets standards.

Cutting to Length and Deburring：The tube is cut to fixed lengths  with a precision cutter, and the ends are deburred to remove sharp edges.

Surface Treatment：Pickling and passivation: Remove surface scale and welding residues, forming a passive film to enhance corrosion resistance.Polishing: Mirror or matte polishing as needed to improve surface finish and aesthetics.

Quality Inspection：Inspect dimensional tolerance, wall thickness uniformity, weld strength, corrosion resistance, etc., to meet standards like ASTM or GB.

• Specifications