Hollow Structural Section HSS

Hollow structural section HSS is a type of structural steel with a closed cross-section—essentially a "hollow load-bearing profile"—manufactured from low-carbon or low-alloy steel via cold-forming or hot-rolling and welding. Thanks to its closed cross-section, it offers superior moment of inertia and torsional rigidity compared to open profiles of the same weight, allowing it to support heavier loads with a smaller cross-sectional area. It supports welding and bolting on all four sides, simplifies connection detailing, and is ideal for modular assembly; its seamless, enclosed form is aesthetically pleasing, minimizes stress concentrations, and makes it suitable for exposed architectural structures.

Key Features

① High Load-Bearing and Torsional Resistance

Hollow structural section HSS members feature a closed cross-section that delivers outstanding moment of inertia and torsional rigidity relative to its cross-sectional area. Using the same amount of material, HSS can withstand greater bending moments and torque than open profiles like angle iron or channel steel. It is suitable for use as primary load-bearing columns and beams, as well as for applications subject to wind, snow, or eccentric loads. For projects prioritizing lightweight structures and material efficiency, this translates to reduced steel consumption, lighter foundation loads, and lower overall costs.

② Square/Rectangular Profile and Easy Assembly

Square and rectangular tubes feature flat surfaces on all four sides, facilitating alignment with connection plates, purlins, clamps, and end plates, while allowing for direct welding, bolting, or riveting. Connection designs do not require the additional stiffening plates often needed for open profiles, resulting in simpler joint configurations, higher on-site assembly efficiency, and lower error rates—making them particularly well-suited for modular and prefabricated construction.

③ Integrated Forming and Dimensional Stability

Manufactured via cold-forming or high-frequency welding, these sections feature straight bodies, flush ends, and uniform wall thickness, with strictly controlled tolerances for side length and straightness. Materials can be cut and joined immediately upon delivery, eliminating the need for on-site straightening, edge trimming, or remedial welding—an advantage that is particularly beneficial for distributed projects with tight schedules and large installation volumes. 

④ Wide Range of Surface Treatment Options

Hollow structural section HSS support various treatment processes, such as hot-dip galvanizing and Zinc-Aluminum-Magnesium (Zn-Al-Mg) coating; coatings are applied uniformly and continuously without gaps. Specifications can be selected based on anti-corrosion requirements for coastal, high-humidity, or industrial environments, ensuring a service life of over 25 years when combined with proper structural design.

⑤ High Application Compatibility

These sections serve dual purposes as both support structures and building frameworks; this versatility reduces the variety of materials to be stocked and alleviates inventory pressure.

Technical Specifications

Item	Specification
Product Name	Hollow Structural Section HSS
Section Type	Square (SHS), Rectangular (RHS)
Common Material Grade	Q235B, Q355B, Q355C (Mild Steel / Low Alloy Structural Steel)
Forming Process	Cold forming, High-frequency longitudinal welding, Hot-rolled seamless / welded
Square & Rectangular Tube Dimensions	40×40, 60×60, 80×80, 100×100, 120×120, 60×40, 80×40, 100×50, 120×80, 160×80, etc.
Round Tube Outer Diameter	Φ32, Φ48, Φ60, Φ76, Φ89, Φ114, etc.
Wall Thickness	1.5mm ~ 8.0mm (selected according to section and application)
Standard Length	6m (custom cut length available: 3m / 9m / 12m or cut per drawing)
Surface Treatment	Hot-dip galvanized, Zinc-Aluminum-Magnesium coating, Bare finish
Applicable Standards	GB/T 6728, EN 10219, ASTM A500, GB/T 13793, etc.
Tolerance	Side dimension tolerance ±0.5mm, wall thickness tolerance ±0.2mm, straightness ≤2mm/m
End Treatment	Plain end / Bevel end / Hole punching per drawing

Construction Process

① Requirement Confirmation and Design Review: 

After you provide drawings, cross-sectional dimensions, and usage scenarios, our technical team reviews the specifications for suitability—checking material grades, wall thicknesses, cut lengths, and surface treatments against local wind loads, snow loads, and corrosion levels. Once confirmed, we provide a quote and delivery schedule to prevent delays caused by rework due to specification errors.

② Raw Material Preparation and Production Scheduling: 

Leveraging a 50,000-ton raw material reserve, we retrieve strip steel of the required grade and route it to cold-roll forming or high-frequency welding lines. With an annual capacity of 500,000 tons and over 40 production lines, we can run multiple lines simultaneously; large orders are split into batches to ensure continuous, uninterrupted supply.

③ Forming and Secondary Processing: 

Tubing undergoes cold-roll forming, high-frequency welding, and precision cutting on the production line. Subsequent processing—such as hole punching, beveling, bending, corner cutting, and end grinding—is performed according to drawings. This yields ready-to-assemble semi-finished or finished components, eliminating the need for secondary processing at the customer's site.

④ Anti-Corrosion Surface Treatment: 

Materials undergo hot-dip galvanizing, Zn-Al-Mg coating, or powder coating as required by the project, ensuring uniform coating thickness and continuity without bare spots. For regions with high salt-spray or severe corrosion risks, coating standards can be upgraded, and thickness and adhesion tests are conducted prior to shipment. 

⑤ Quality Inspection and Reporting: 

Strict adherence to four major inspection stages and sixteen standards throughout production—incoming raw material inspection, in-process spot checks during forming, full inspection of finished products, and final pre-shipment inspection. Each batch undergoes spot checks for side length, wall thickness, straightness, weld appearance, and coating quality; accompanying documentation includes raw material test reports, production quality inspection reports, and third-party test reports.

⑥ Packaging and Shipment: 

Finished hollow structural section HSS products are bundled and wrapped in waterproof film according to container loading requirements, with edge protectors or wooden crating used where necessary. Located adjacent to the Port of Tianjin, the factory facilitates immediate container loading and shipment following customs clearance, ensuring delivery to the client's project site within the agreed timeframe, while also providing accompanying drawings, certificates of conformity, and technical support for installation.

FAQ

Q1: Is HSS the same as standard square tubing? 

Hollow structural section HSS is the standard term for structural closed-profile steel, encompassing square, rectangular, and circular sections. We manufacture according to structural standards—with clearly defined specifications for material, tolerances, and load-bearing performance—distinguishing them from ordinary commercial-grade tubing.

Q2: What section sizes can you produce? 

Standard square and rectangular tubes range from 40×40 to 160×80, and circular tubes from Φ32 to Φ114, with wall thicknesses of 1.5–8mm. Non-standard sizes can be custom-manufactured based on drawings, as our tooling and production lines support such requirements.

Q3: What is the typical lead time for bulk orders? 

It depends on the specifications and quantity of the hollow structural section HSS required. Standard batch orders are scheduled according to the contract timeline, while custom lengths and hole-punching may add slightly to the duration. We provide a clear delivery date before the order is placed and can accommodate urgent requests.

Q4: What anti-corrosion options are best for coastal projects? 

For high-salinity environments, we recommend Zinc-Aluminum-Magnesium coating or heavy-duty galvanizing; standard hot-dip galvanizing suffices for general outdoor use. We provide anti-corrosion solutions tailored to your project location, complete with salt spray and coating test data.

Q5: Can you handle processing tasks like hole-punching and cutting? 

Yes. We can perform hole-punching, beveling, bending, and precision cutting according to your drawings prior to shipment, thereby reducing on-site processing requirements—provided accurate fabrication drawings are supplied.

Q6: Have you supplied materials for large-scale projects? 

Yes. We have a cumulative global shipment volume exceeding 27GW, including a single 1.2GW project in the Middle East. We have extensive experience delivering large-span and high-volume orders and can provide references to past projects.