What is HSS Steel? Sizes, Grades, and Properties

November 18, 2025 | Categorized in:

stack of square hss tubing

HSS steel (short for Hollow Structural Sections) is a type of high-strength steel tubing with a hollow cross-section. It’s the kind of steel you’ll find just about everywhere: holding up buildings, reinforcing bridges, framing heavy equipment, even supporting signposts on the side of the highway.

Why? Because it’s efficient. It’s reliable. And it just makes sense for a wide range of structural applications.

In this guide, we’ll break down exactly what HSS steel is, what shapes and grades it comes in, how to read sizing charts, and where it’s most commonly used. Whether you’re sourcing materials for a job or just want to understand your options better, this guide has you covered.

What is HSS Steel?

HSS steel (short for Hollow Structural Sections), is a group of high-strength, welded steel tubing products that are used extensively across structural and architectural applications. Often referred to simply as HSS tubing or structural steel tubing, this material is a staple in the construction world thanks to its efficiency in both design and function. 

These steel shapes feature hollow cross sections, most commonly in square, rectangular, or circular (round) shapes. Their top features are uniform strength and high load-bearing capacity.

What Does HSS Stand for in Steel?

In steel, HSS stands for Hollow Structural Section. It’s not a specific alloy or grade of steel. HSS is a term that defines the shape and usage of the steel. The name is straightforward: 

  • “Hollow” means you’re working with steel that has an empty interior, which reduces its weight without losing strength.
  • Then, “structural” means something built to carry a load, such as frameworks, where support, strength, and stability matter.

Different HSS Tube Steel Shapes

HSS tubing comes in three distinct shapes: square, rectangular, and round. With each offering unique structural advantages:

1. Square HSS Tubing

Square HSS is one of the most widely used structural shapes due to its uniform strength on all sides. It’s ideal for applications like columns, braces, and supports, especially where clean lines and consistent load distribution are required. You’ll find square HSS in everything from commercial buildings to industrial machinery frames.

2. Rectangular HSS Tubing

Rectangular HSS offers directional strength, which makes it perfect for horizontal beams, platforms, and truss systems. Because it has a wider or taller profile, it’s commonly used where one axis bears more load than the other. It’s a smart pick for structural support in bridges, trailers, and large-scale steel frameworks.

3. Round HSS Tubing

Round HSS, which sometimes overlaps with steel pipe dimensions (NPS) and steel grades, is used where torsional resistance and multidirectional load-bearing capacity are key. Its circular cross-section helps evenly distribute stress, making it a top choice for guardrails, signposts, architectural supports, and outdoor applications. Round HSS also provides an aesthetic edge in exposed designs.

Learn more about tubing vs. pipes from AISC here.

HSS Steel Tubing Benefits & Applications

You’ll find HSS used in just about every industry that demands long-term durability and smart structural design. Here’s a breakdown of its top benefits and applications:

Strength and Durability

HSS tubing has an outstanding strength-to-weight ratio, making it ideal for structural and load-bearing applications. The closed shape resists torsion and buckling, which is why it’s so common in commercial buildings, bridges, and infrastructure like highway signage and public walkways.

Weight Savings

Because HSS is hollow, it delivers strength without the extra weight. That makes it easier to handle during fabrication and faster to install on-site. In industries like automotive, trailers, and heavy equipment, weight savings can also mean better fuel efficiency and performance.

Design Flexibility

HSS tubing’s uniform shape and tight tolerances make it easy to cut, drill, and weld. That keeps fabrication efficient and straightforward, key for industries like agriculture, where HSS is used in everything from irrigation structures to equipment frames and fencing systems. It’s also common in heavy equipment manufacturing, where reliability in frames, booms, and stabilizers is non-negotiable.

Corrosion Resistance 

With the right coating or galvanizing, HSS tubing offers resistance to weather, chemicals, and wear. That’s why it’s heavily used when tubing is exposed to harsh environments on rigs, substations, and transmission towers. Its closed shape also requires less surface prep and paint than open sections, translating to lower coating costs and faster install times.

HSS Steel Grades

When it comes to HSS tubing, understanding the grade is key to choosing the right material for your application, whether you’re designing structural supports or fabricating equipment.

At Service Steel, we carry HSS tubing that meets the most commonly used ASTM standards. You can also check out our full guide to steel grades to compare across other product types. That being said, here are the three most common HSS-related steel grades we supply:

ASTM A500

ASTM A500 is the most commonly used specification for HSS tubing in North America. It covers cold-formed carbon steel tubing in round, square, and rectangular shapes. Its top features are its weldability and formability, making A500 widely used in structural framing, equipment fabrication, and general construction.

ASTM A1085

ASTM A1085 is a newer spec developed for applications that demand more precision and predictable performance. This HSS steel grade eliminates uncertainty in design and helps reduce overbuilding, which can ultimately improve efficiency in high-performance structures.

ASTM A53

ASTM A53, while primarily a pipe specification, is often used for round HSS tubing, especially when both structural integrity and fluid conveyance are needed. This one is commonly found in projects where round profiles are preferred and tubing may need to serve both mechanical and structural purposes.

HSS Size Chart and Dimensions

Our HSS tubing size chart lists key specifications like outside diameter, wall thickness, and weight per foot. These measurements help you choose the right tubing based on strength requirements, fit, and overall weight. HSS sizes are listed in inches and decimals, making them easy to read and apply to real-world builds.

Click here to view our round tubing and pipe sizing chart (PDF).

Contact Our Team for a Custom Quote on HSS Steel Tubing

HSS steel tubing is strong, efficient, and built to perform. Whether you’re working on a structural frame, a piece of heavy equipment, or a utility project, HSS offers the kind of strength-to-weight ratio and design flexibility that just makes sense. 

At Service Steel Warehouse, we stock a deep inventory of carbon steel HSS tubing—all made to meet ASTM specs and ready to ship fast. Get in touch with us today for a free, customized quote. We’ll make sure your next project starts with the right steel.