YS STEEL manufactures Square and Rectangular Tubes from hot-rolled or cold-rolled steel strip through high-frequency electric resistance welding, also known as ERW. The strip is progressively formed into a round shape, welded longitudinally, then reshaped into square or rectangular geometry. This process yields a consistent cross-section with tight corner profiles and reliable weld integrity. For thicker wall sections or special mechanical requirements, YS STEEL also supplies hot-finished square and rectangular hollow sections produced to EN 10210.
The production line at YS STEEL includes uncoiling, leveling, edge conditioning, forming, high-frequency welding, sizing, straightening, cutting, and final inspection. Weld seams are subjected to online eddy current testing and, for critical applications, ultrasonic testing. Dimensional checks are performed at multiple stations to ensure the outer dimensions, wall thickness, corner radius, and straightness meet the specified tolerances.
Every batch of square and rectangular steel tube is traceable to its heat number and original mill certificate. YS STEEL provides EN 10204 3.1 or 3.2 certification upon request, as well as third-party inspection by SGS, BV, or TUV when required. This level of documentation matters for structural engineers, code inspectors, and project owners who require full material accountability.
YS STEEL stocks and produces square and rectangular steel tube in a broad dimensional range. The standard product parameters include the following options:
Inch-based sizes are also available for North American projects, including common dimensions such as 1/2" x 1/2", 1" x 1", 2" x 2", 3" x 3", 4" x 4", and larger rectangular sections like 6" x 4" and 8" x 4". YS STEEL can match imperial wall thickness schedules including Sch 10, Sch 40, and Sch 80 where applicable.
The selection of material standard directly influences the mechanical properties, chemical composition, and suitability for a given application. The table below summarizes the most common standards supplied by YS STEEL for Square and Rectangular Tubes.
| Standard | Typical Steel Grades | Common Applications |
|---|---|---|
| ASTM A500 | Grade A, Grade B, Grade C, Grade D | Structural columns, building frames, bridges, sign supports, general construction |
| ASTM A513 | MT1020, MT1025, MT1030, MT1040 | Mechanical tubing, automotive components, furniture, agricultural equipment |
| ASTM A847 | ASTM A847 | Weathering steel tube for exposed architectural and structural applications |
| EN 10219 | S235JRH, S275J0H, S355J2H | Cold-formed welded structural hollow sections for European projects |
| EN 10210 | S235JRH, S275J0H, S355J2H | Hot-finished structural hollow sections with improved toughness |
| JIS G3466 | STKR400, STKR490 | General structural applications for Japanese and Asian markets |
| GB/T 6728 | Q195, Q235, Q345 | Chinese standard structural hollow sections for domestic and export use |
YS STEEL can also supply dual-certified material to cover ASTM and EN requirements in one heat, which is useful for international projects that must satisfy multiple code jurisdictions.
Dimensional accuracy is one of the most important factors for Square and Rectangular Tubes because end users frequently weld, drill, or bolt directly to the flat surfaces. YS STEEL applies the following general tolerances in accordance with the relevant standard. Tighter tolerances can be agreed upon for critical applications.
| Parameter | Tolerance Range |
|---|---|
| Outer dimension (side length) | ±0.5% of nominal dimension, typically ±0.25 mm to ±1.0 mm depending on size |
| Wall thickness | ±10% for wall thickness below 5 mm; ±0.5 mm for wall thickness 5 mm to 15 mm; ±8% for thicker walls |
| Corner radius | 1.5 to 3.0 times the wall thickness, depending on forming method and standard |
| Straightness | Maximum 0.15% of total length, typically 2 mm per 1,000 mm |
| Squareness of sides | 90° ±1° for most structural sections |
| Length | Standard fixed length ±25 mm; custom cut length ±3 mm or tighter upon request |
| End squareness | Cut ends square within 2° of perpendicular to the tube axis |
YS STEEL uses laser measurement systems during production to monitor these tolerances in real time. Random inspections are recorded and archived for each heat, so customers can review dimensional data before shipment.
The mechanical properties of square and rectangular steel tube vary by standard and grade. The table below lists typical minimum values for common structural grades supplied by YS STEEL.
| Grade | Minimum Yield Strength (MPa) | Tensile Strength Range (MPa) | Minimum Elongation (%) |
|---|---|---|---|
| ASTM A500 Grade B | 315 | 400 - 480 | 18 |
| ASTM A500 Grade C | 345 | 425 - 505 | 18 |
| S235JRH | 235 | 360 - 510 | 24 |
| S275J0H | 275 | 410 - 560 | 20 |
| S355J2H | 355 | 470 - 630 | 20 |
| STKR400 | 245 | 400 - 510 | 23 |
| STKR490 | 325 | 490 - 610 | 19 |
| A513 MT1020 | 205 | 330 - 410 | 20 |
Impact tests for low-temperature toughness are available for EN 10210 and S355J2H grades. YS STEEL can also conduct Charpy V-notch testing at 0°C, -20°C, -40°C, or -50°C when specified by the project.
Square and rectangular steel tube from YS STEEL can be supplied with several surface conditions to suit different environments and finishing requirements.
The surface condition affects weldability, paint adhesion, and corrosion resistance. YS STEEL technical staff can recommend the most cost-effective coating for the intended service environment.
Square and rectangular steel tube is used in a wide range of industries because its flat sides simplify attachment and its closed section resists torsional loads better than open profiles such as angles or channels.
Because square and rectangular steel tube is available in both light-gauge and heavy-wall versions, it can serve everything from small mechanical components to primary structural members carrying hundreds of kilonewtons.
Q: Can YS STEEL provide custom cut lengths?
A: Yes. YS STEEL offers standard random lengths of 6 meters, 12 meters, and 5.8 meters, but custom fixed lengths are available from 0.5 meters to 24 meters, depending on the section size and wall thickness. Cut-to-length tolerance can be controlled to ±3 mm for standard structural applications and tighter if required. In addition to cutting, YS STEEL provides end chamfering, drilling, slotting, miter cutting, and bundle tagging according to customer specifications. For OEM buyers, YS STEEL can supply ready-to-weld components that reduce handling and processing time at the customer facility.
Q: What surface treatments are available?
A: YS STEEL offers black as-welded, oiled, hot-dip galvanized, pre-galvanized, acid pickled and oiled, painted, and powder-coated surface finishes. The best option depends on the service environment, required corrosion resistance, and whether the tube will be painted after installation. Hot-dip galvanizing provides the longest outdoor service life and is commonly specified for solar structures, agricultural equipment, guardrails, and marine environments. Pre-galvanized tube is more economical for lighter gauges and indoor applications. Oiled or black finish is typically used when the tube will be primed or painted on site, or when it is embedded inside a larger assembly.
Q: How does YS STEEL ensure the quality of Square and Rectangular Tubes welds?
A: YS STEEL uses high-frequency electric resistance welding with continuous parameter monitoring. Weld integrity is verified through online eddy current testing, and destructive testing is performed on samples from each production run to confirm weld strength and ductility. Flattening tests, flare tests, and tensile tests are conducted according to the applicable standard. For critical orders, YS STEEL can perform ultrasonic testing on the weld seam and provide detailed inspection reports. All testing data is traceable to the original heat number, and customers can request EN 10204 3.1 or 3.2 certification with every shipment.
Q: What is the minimum order quantity and lead time?
A: For standard sizes and grades, YS STEEL accepts orders from 1 metric ton per size, with mixed-size container load orders starting around 25 metric tons for export. For custom sizes or special grades, the minimum order quantity is typically 5 to 10 metric tons depending on the production schedule. Lead time for standard stock items is 7 to 15 days after order confirmation. For custom rolling or hot-dip galvanizing, production lead time is usually 20 to 35 days. YS STEEL provides a detailed production and shipping schedule before order confirmation so buyers can plan project timelines accurately.
