If you have ever ordered steel tubing or browsed a supplier catalogue, you have probably come across terms like SHS, RHS, or HSS. These abbreviations can feel confusing at first, but they all describe a family of hollow steel profiles that are widely used across construction, maritime, offshore, and industrial applications. Understanding what these terms mean, and when to use each type, helps you specify the right material the first time and avoid costly mistakes down the line.
What are square steel tubes called?
Square steel tubes are most commonly called Square Hollow Sections, abbreviated as SHS. This is the standard industry term used across Europe and internationally. In North America, the same product is often referred to as Hollow Structural Sections, or HSS. Both terms describe the same basic product: a steel tube with equal width and height on all four sides, forming a perfect square cross-section.
You may also hear the term box section or square tube used informally, particularly in fabrication workshops and on construction sites. These are not technical designations, but they refer to the same product. When ordering from a supplier or reviewing technical documentation, SHS is the term you are most likely to encounter in European and international contexts.
What is the difference between SHS, RHS, and HSS?
These three abbreviations are closely related but describe slightly different profiles:
- SHS (Square Hollow Section): All four sides are equal in length. The cross-section is a perfect square. This is the product most people picture when they think of a square steel tube.
- RHS (Rectangular Hollow Section): Two sides are longer than the other two. The cross-section is a rectangle. RHS profiles are often used where load-bearing in one direction is more important than in another.
- HSS (Hollow Structural Section): The North American umbrella term for both square and rectangular hollow sections. When someone in the US or Canada says HSS, they may mean either an SHS or an RHS profile, depending on the dimensions specified.
In practice, SHS and RHS are often grouped together under the broader category of structural hollow sections. The key difference is the aspect ratio: an SHS has equal dimensions on all sides, while an RHS does not. When specifying your material, always confirm the exact dimensions rather than relying on the abbreviation alone.
What are square steel tubes used for?
Square hollow sections are valued for their structural efficiency and clean appearance. Because the profile is symmetrical, it handles loads equally well from any direction, making it a popular choice for columns, frames, and supports. Common applications include:
- Structural columns and support frames in construction and industrial buildings
- Offshore platform structures and equipment supports
- Ship and vessel deck structures and railings
- Mechanical equipment frames and machinery bases
- Architectural features, fencing, and gates
- Trailers, vehicle chassis, and transport equipment
The hollow core of an SHS profile reduces weight compared to a solid bar of equivalent size, which is a significant advantage in maritime and offshore environments where weight management matters. The square profile also makes welding and connecting sections straightforward, which speeds up fabrication on site or in a workshop.
What steel grades are square hollow sections available in?
Square hollow sections are produced in a range of steel grades to suit different structural and environmental requirements. The most common grades include:
S235 and S355 are the standard European structural steel grades, defined under EN 10219 and EN 10210. S235 is a general-purpose grade suitable for light structural applications, while S355 offers higher yield strength and is preferred for heavier loads and more demanding environments.
ASTM A500 is the North American equivalent standard for cold-formed hollow structural sections, commonly specified in the US and for projects following American standards. For projects in maritime or offshore environments, marine-grade and higher-specification materials may be required, including grades with improved corrosion resistance or impact toughness at low temperatures.
Galvanized SHS profiles are also available for applications where corrosion protection is a priority, such as outdoor structures, port facilities, or coastal environments. When in doubt about which grade suits your project, a knowledgeable supplier can help you match the specification to the application.
How do you specify the right square tube size for your project?
Specifying a square hollow section correctly requires more than just the outer dimension. A complete specification typically includes:
- Outer dimension: The width and height of the square profile, for example 100 x 100 mm.
- Wall thickness: The thickness of the steel wall, for example 5 mm or 8 mm. Thicker walls increase load-bearing capacity and weight.
- Steel grade: The material standard and grade, such as S355 or ASTM A500.
- Surface finish or treatment: Whether the tube is black (untreated), galvanized, primed, or requires another surface treatment.
- Length: Standard stock lengths or custom cut lengths depending on your project needs.
Getting these details right from the start avoids delays, wasted material, and the risk of specifying a tube that is either overbuilt for the application or structurally insufficient. If you are working from a technical drawing, the specification is usually already defined. If you are sourcing based on a general requirement, it is worth consulting with your supplier to confirm the right combination of dimensions and grade.
Tube sizes in a professional supply context can run up to 20 inches and beyond, so the range of available options is broad. Custom cutting and processing services can bring stock material to the exact dimensions your project requires, which saves time on site and reduces fabrication waste.
How Marine Steel helps you source the right square hollow section
Finding the right SHS profile quickly and without complications is exactly what we are set up to do. At Marine Steel, we stock a wide range of square hollow sections and related profiles across our warehouses in Rotterdam and Houston, ready for fast delivery to maritime, offshore, construction, and industrial clients worldwide.
Here is what we offer:
- Broad stock of SHS and RHS profiles in multiple grades and dimensions
- Custom cutting, drilling, rolling, and surface treatments including galvanizing and priming
- Material certificates and documentation where required
- Technical advice to help you specify the right product for your application
- One-stop supply so you do not need to coordinate multiple suppliers
Whether you know exactly what you need or are still working out the specification, we are happy to think along with you. Get in touch with our team and tell us about your project. We will make sure you get the right material, processed to your requirements, delivered without delay.
