Struggling to pick the right steel for your next project? The choice often comes down to one crucial detail: hollow section sizes. Whether you’re building a lightweight frame or a heavy-duty support system, selecting the correct dimensions can make or break the outcome. From small 20×20 SHS to large structural RHS and CHS profiles, each size offers unique advantages that builders, fabricators, and engineers rely on every day.

What Are Hollow Sections?

In steel construction, hollow sections are tubular profiles with a hollow core. They are widely used in building, fabrication, infrastructure, and even decorative projects. The three most common types are:

• SHS (Square Hollow Section) – equal sides, ideal for balanced strength.
• RHS (Rectangular Hollow Section) – longer on one axis, perfect for beams and spanning structures.
• CHS (Circular Hollow Section) – round profile, often chosen for aesthetics and torsional strength.

Because of their versatility, builders and engineers across the world depend on the wide variety of hollow section sizes to match project requirements.

Why Hollow Section Sizes Matter

Choosing the right hollow section sizes is not just a technical step—it is the foundation of structural reliability, cost-efficiency, and long-term performance. The dimensions of a hollow section directly affect how much weight it can bear, how it distributes stress, and how well it fits into a specific design. Using a section that is too small can result in dangerous structural failures under heavy load, while selecting one that is too large can unnecessarily drive up material costs, fabrication expenses, and overall project weight.

For example, smaller dimensions such as 20×20 mm or 40×40 mm SHS (Square Hollow Sections) are widely used in lightweight structures like fencing, furniture frames, and small-scale supports. They are easy to handle, affordable, and provide sufficient strength for non-heavy-duty applications. On the other hand, medium sizes such as 100×100 mm SHS or 150×50 mm RHS (Rectangular Hollow Sections) are commonly used in building frames, columns, and industrial fabrications, where both strength and stability are required. For large-scale construction, sizes like 200×200 mm SHS or 250×150 mm RHS are preferred, as they provide the structural capacity needed for bridges, warehouses, and multi-storey buildings.

Understanding these variations allows builders and fabricators to balance three critical factors: strength, budget, and ease of fabrication. A well-chosen hollow section not only ensures safety and compliance with engineering standards but also helps control costs by avoiding material wastage and overengineering. In industries such as construction, manufacturing, and even automotive, this balance is what keeps projects both competitive and reliable.

Ultimately, hollow section sizes matter because they transform design concepts into safe, practical, and cost-effective structures. By matching the right dimensions to the right application, professionals can achieve efficiency without compromising on durability.

Common Hollow Section Sizes

Hollow sections are manufactured in a wide variety of sizes to suit everything from light fabrication to heavy structural engineering. The most common types are Square Hollow Sections (SHS), Rectangular Hollow Sections (RHS), and Circular Hollow Sections (CHS). Below are extended examples of hollow section sizes you’ll often find in the market:

Square Hollow Section (SHS) Sizes

• 20 x 20 x 1.6mm – lightweight, used for gates, display stands, and decorative frameworks.
• 25 x 25 x 2mm – common in small furniture, shelving, and residential projects.
• 40 x 40 x 2.5mm – widely used in garden structures, fencing posts, and light supports.
• 60 x 60 x 3mm – mid-range size, suitable for carports, railing frames, and small industrial fabrications.
• 80 x 80 x 4mm – versatile option for moderate load-bearing in structural projects.
• 100 x 100 x 4mm – strong, commonly applied in building columns, supports, and workshop frames.
• 150 x 150 x 6mm – heavy-duty SHS used in large industrial sheds and infrastructure.
• 200 x 200 x 8mm and above – large-scale construction, warehouses, and bridge structures.

Rectangular Hollow Section (RHS) Sizes

• 40 x 20 x 2mm – light-duty RHS used in shelving and furniture frames.
• 50 x 25 x 2.5mm – useful for gates, partitioning, and small frameworks.
• 75 x 50 x 3mm – versatile, often chosen for fencing and mid-weight structures.
• 100 x 50 x 3mm – a popular choice for building frames, light columns, and load-bearing walls.
• 150 x 100 x 4mm – stronger RHS for roofing beams and larger industrial applications.
• 200 x 100 x 6mm – suitable for roof trusses, transport trailers, and heavy-duty fabrications.
• 300 x 200 x 8mm – ideal for large-scale commercial projects and bridges.
• 400 x 200 x 10mm and larger – designed for major construction projects, warehouses, and structural reinforcements.

Circular Hollow Section (CHS) Sizes

• 21.3mm OD x 2mm – small, perfect for handrails, guardrails, and lightweight piping.
• 33.7mm OD x 2.6mm – used in fabrication of railings and small supports.
• 48.3mm OD x 3.2mm – standard size in scaffolding and temporary structures.
• 60.3mm OD x 3.6mm – common for columns, bracing, and mid-load structures.
• 88.9mm OD x 4mm – widely used in structural fabrication and automotive applications.
• 114.3mm OD x 5mm – suitable for mid-range load-bearing projects and infrastructure.
• 168.3mm OD x 6.3mm – strong CHS for pipelines and heavy fabrication work.
• 219.1mm OD x 8mm – heavy-duty pipelines, structural columns, and industrial plants.
• 273mm OD x 10mm and above – massive structures, offshore platforms, and bridge construction.

Most hollow section sizes are manufactured in 6m and 12m lengths, though suppliers often provide custom cut-to-size services to minimize waste and match specific project requirements.

Applications of Different Hollow Section Sizes

• Small Hollow Section Sizes – Used in furniture, gates, fences, and decorative applications.
  
• Medium Hollow Section Sizes – Common in building frames, machinery, supports, and light structural work.
  
• Large Hollow Section Sizes – Essential for heavy construction such as bridges, towers, warehouses, and industrial plants.
  

Benefits of Choosing the Right Hollow Section Sizes

1. Optimized Structural Strength – Ensures the material can handle the intended load safely.
   
2. Cost Efficiency – Prevents overspending on unnecessary thickness or weight.
   
3. Design Flexibility – Different hollow section sizes allow for creative and functional design solutions.
   
4. Ease of Fabrication – Proper sizing makes welding, cutting, and assembly more efficient.
   
5. Durability – Correct sizes combined with the right finish (mild steel, stainless steel, galvanised) guarantee long service life.
   

Final Thoughts

Whether you are a builder, architect, or fabricator, understanding hollow section sizes is crucial to project success. With such a wide range of SHS, RHS, and CHS options available, there is a perfect size for every requirement—whether it’s lightweight decorative fabrication or heavy-duty structural support.

For the best results, consult with your steel supplier to confirm the most appropriate hollow section sizes for your project, ensuring safety, efficiency, and long-term performance.

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