If you work in construction, maritime, or industrial procurement, you have probably come across the term hollow section steel more than once. But with several types available and each suited to different applications, it is not always obvious which one you need. This guide breaks down the main types of hollow section steel, explains the differences between them, and helps you make the right choice for your project.
What is hollow section steel and where is it used?
Hollow section steel is exactly what the name suggests: a steel profile with a hollow interior running along its length. Unlike solid steel bars or rods, hollow sections are lighter relative to their strength, which makes them highly efficient structural elements. They are used wherever you need strength, rigidity, and load-bearing capacity without unnecessary weight.
You will find hollow section steel across a wide range of industries and applications:
- Structural frameworks in buildings, bridges, and port infrastructure
- Offshore platforms and marine structures
- Cranes, lifting equipment, and mechanical frames
- Shipbuilding and vessel construction
- Industrial machinery and support structures
- Architectural and design applications where appearance matters
Because hollow sections combine strength with a clean, predictable profile, they are a go-to choice for engineers and procurement professionals who need materials that perform consistently under load.
What are the main types of hollow section steel?
There are three primary types of hollow section steel, each defined by its cross-sectional shape. The shape directly affects how the section performs under different types of stress, how easy it is to fabricate, and which applications it is best suited for.
The three main types are:
- Square Hollow Section (SHS) — a square cross-section with equal sides
- Rectangular Hollow Section (RHS) — a rectangular cross-section with two pairs of unequal sides
- Circular Hollow Section (CHS) — a round, tubular cross-section
Each type has its own strengths and preferred use cases, which we will cover in the next section.
What’s the difference between SHS, RHS, and CHS?
Square Hollow Sections (SHS) are popular in construction and fabrication because they are easy to connect and weld. Their equal sides make them straightforward to work with when building frames, columns, and supports. They resist torsion well, meaning they hold up effectively when twisting forces are applied.
Rectangular Hollow Sections (RHS) are the most widely used type in structural applications. Because the two axes have different dimensions, RHS profiles can be oriented to maximise bending resistance in a specific direction. This makes them ideal for beams, lintels, and horizontal structural members where loads are predictable and directional.
Circular Hollow Sections (CHS) are the strongest performers when loads come from multiple directions simultaneously. Their round shape distributes stress evenly across the entire cross-section, which makes them the preferred choice for columns, offshore structures, marine piling, and any application where forces are not limited to one axis. CHS also has excellent resistance to torsion and is widely used in fluid-carrying applications such as pipework.
In short: use RHS for beams and directional loads, SHS for frames and connections, and CHS for columns, multi-directional loads, and marine or offshore environments. If you are unsure which profile fits your project, reach out to our team and we will help you figure it out.
What steel grades are used for hollow sections?
The steel grade determines the mechanical properties of the hollow section, including its yield strength, tensile strength, and weldability. Choosing the wrong grade can lead to structural failure or unnecessary over-engineering and cost.
The most commonly used grades for hollow sections include:
S235 and S275 are general-purpose structural grades used in lighter applications where extreme strength is not required. They are easy to weld and widely available.
S355 is the workhorse of structural steel. It offers significantly higher yield strength than S235, making it the standard choice for heavy structures, offshore applications, and demanding industrial environments. Most hollow sections used in serious construction and maritime work are specified in S355.
Stainless steel grades such as 304 and 316 are used where corrosion resistance is critical. Grade 316, in particular, is preferred for marine and offshore environments because of its resistance to saltwater and chloride exposure.
For applications governed by American standards, ASTM grades such as ASTM A500 are commonly specified for hollow sections. Always check whether your project requires European EN standards or ASTM standards before ordering, as the two systems are not directly interchangeable.
How do you choose the right hollow section for your project?
Choosing the right hollow section comes down to four key factors: the type of load, the environment, the required dimensions, and the applicable standards or certifications.
Start with the load type. If your structure will primarily carry bending loads in one direction, an RHS is usually the most efficient choice. If loads come from multiple directions or you need a column, CHS is worth considering. For general framing and connections, SHS is often the most practical option.
Next, consider the environment. Structures exposed to seawater, chemicals, or high humidity need either a corrosion-resistant steel grade or an appropriate surface treatment such as galvanizing or priming. Offshore and marine applications almost always require stainless steel or properly coated carbon steel.
Then confirm the dimensions. Wall thickness, outer dimensions, and length all affect both structural performance and compatibility with fittings and connections. Getting these wrong can create significant rework costs. You can explore the full range of steel products we stock to check available dimensions and specifications.
Finally, check the required certifications. Many projects in maritime, offshore, and industrial sectors require material certificates, class certification, or compliance with specific standards. Make sure your supplier can provide the documentation you need.
Where can you source hollow section steel quickly and reliably?
Speed and reliability matter enormously in procurement, particularly in maritime and offshore work where delays translate directly into cost. Finding a supplier who holds broad stock, can advise on specifications, and delivers without unnecessary back-and-forth is not always easy.
The most reliable approach is to work with a supplier who combines technical knowledge with genuine stock availability. That means someone who can confirm dimensions, grades, and certifications quickly, and who has the capacity to process and deliver your order without routing it through multiple parties.
How Marine Steel helps with hollow section steel
We stock a wide range of hollow section steel at our warehouses in Rotterdam and Houston, ready for fast delivery to maritime, offshore, construction, and industrial clients worldwide. With over 15 years of experience, we know these products inside out and are happy to advise on grades, dimensions, and specifications.
Here is what we offer:
- SHS, RHS, and CHS in a range of grades including S355 and stainless steel
- Custom cutting, drilling, rolling, bending, and surface treatments including galvanizing and priming
- Material certificates and class certification where required
- Stock in both Rotterdam and Houston for fast international delivery
- One point of contact who thinks along with you and helps you get the right product the first time
No need to explain your project twice or chase multiple suppliers. We handle it as a complete package. Contact us today for a fast quote on hollow section steel.
