ASTM A500 Q235 Q355 ERW Welded Black Square Steel Tube High Strength Square Hollow Section For Building Frame Infrastructure Mechanical Structural Support Projects

ASTM A500 Q235 Q355 ERW Welded Black Square Steel Tube High Strength Square Hollow Section For Building Frame Infrastructure Mechanical Structural Support Projects
Product description:

Our black carbon steel square tube, also known as square hollow section (SHS), is professionally produced from high-quality Q235 and Q355 carbon steel materials, complying with ASTM A500 international standards. Adopting advanced ERW welded forming technology, the product features uniform wall thickness, smooth surface, straight overall shape and precise dimensional accuracy without deformation. This structural square steel tube boasts outstanding hardness, tensile strength and anti-pressure performance, with excellent welding, cutting and processing properties, easy for secondary fabrication and installation. It is widely applicable for building steel frames, factory workshop structures, road guardrail supports, engineering infrastructure, mechanical equipment brackets and various heavy-load structural projects. We support customized size, wall thickness and length, providing one-stop processing services to meet diverse industrial and construction application demands.

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Manufacturing Process

The production of seamless Square and rectangular tubes begins with a seamless round steel billet. The process includes:

• Piercing: The solid billet is heated and pierced to form a hollow shell.
• Elongation: The hollow shell is rolled and elongated using a mandrel mill or stretch reducer to achieve precise dimensions.
• Shaping: The round tube is then cold-drawn or hot-formed into square or rectangular shapes using advanced forming technology.
• Heat Treatment: Tubes are normalized, annealed, or quenched and tempered to achieve the desired mechanical properties.
• Finishing and Inspection: Each tube undergoes strict non-destructive testing (NDT) such as ultrasonic, eddy current, or hydrostatic testing to guarantee internal and external soundness.

This seamless process ensures excellent dimensional accuracy, smooth inner and outer surfaces, and consistent performance across the entire length of the tube.

Material Grades

Common steel grades for seamless square and rectangular tubes include:

• Carbon Steel: ASTM A106, A53, A519, ST35, ST52, S355, S235
• Alloy Steel: 4130, 4140, 20MnV6, 15CrMo, 12Cr1MoV
• Stainless Steel: 304, 316L, 321, 310S

Each grade offers specific advantages in terms of tensile strength, corrosion resistance, and heat tolerance, allowing users to select the best material for their project requirements.

Advantages of Seamless Square and Rectangular Tubes

• No Weld Seams: Provides uniform strength along the entire tube length.
• High Pressure Resistance: Suitable for hydraulic systems, oil and gas applications, and high-pressure pipelines.
• Excellent Surface Finish: Smooth inner and outer surfaces reduce friction loss and improve flow performance.
• Superior Dimensional Accuracy: Ideal for precision engineering and mechanical fabrication.
• Better Mechanical Performance: Enhanced strength, toughness, and fatigue resistance compared to welded tubes.
• Versatile Forming Options: Easily machined, drilled, or cut to custom lengths.

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Applications:

Welded square and rectangular tubes are used across a wide range of industries due to their adaptability and cost-effectiveness:

• Construction and Infrastructure: Building frames, scaffolding, bridges, and support columns.
• Mechanical Manufacturing: Machine frames, conveyors, and material handling systems.
• Automotive and Transport: Chassis, trailer frames, and structural reinforcements.
• Furniture and Interior Design: Modern furniture frames, handrails, and architectural accents.
• Agricultural and Energy Equipment: Machinery components, greenhouses, and solar panel mounts.
• Shipbuilding and Offshore: Light-duty marine structures and platforms.
• Their combination of formability, strength, and durability makes them suitable for both indoor and outdoor installations.

Quality Standards and Certifications

• Welded square and rectangular tubes conform to international standards, ensuring reliability and global compatibility:
• EN 10219 – Cold-formed welded structural hollow sections
• EN 10210 – Hot-finished structural hollow sections
• ASTM A500 / A513 / A554 – Welded carbon and stainless steel tubes
• JIS G3466 – Structural steel square and rectangular tubes
• ISO 9001 / CE / SGS – Quality assurance and certification compliance

Company profile:

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Why us?

We focus on the research, development, production and sales of seamless steel pipes, Special-shaped steel pipes and hydraulic cylinders. We have a complete production chain and an advanced equipment system, including piercing machines, cold drawing machines, hot rolling machines, high-precision flaw detection and testing equipment. The company has passed multiple authoritative certifications such as ISO9001, API, SGS, CCS, DNV, ABS, CE, RoHS, etc., ensuring that each product complies with international standards. We are committed to providing customers with high-quality, customizable solutions to meet diverse application needs.

Relying on our own built processing base and modern workshops, combined with multiple branches and storage centers across the country, we have achieved sufficient inventory and efficient logistics coordination, significantly shortening the delivery cycle and ensuring the rapid delivery of orders.

We have established a complete service and support system. After the order is signed, the professional after-sales team can provide timely and safe on-site guidance and technical support to ensure that customers are at ease throughout the process from procurement to use.

FAQ:

1. Do you support customized design and production?

Sure. We have a professional engineering team that can conduct customized design and production with special sizes, control systems or OEM according to your requirements.

2. How fast can you deliver?

In stock sizes, it takes 3-5 days. For customized sizes, it takes 30-35 days.

3. What payment methods do you support?

We support TT payment. Generally, 30% to 50% of the payment is made in advance, and the remaining amount is paid before shipment.

4. Can you provide material certification (MTC)?

Yes, we will provide MTC to you after production is completed to ensure that the material quality meets the standards.

5. What is the minimum order quantity?

Generally, we accept trial orders. The minimum order quantity is 1-3 tons, which can be determined according to different products.