Structural Steel Fabrication: Your Ultimate Guide

Welcome to our comprehensive guide on Structural Steel Fabrication. This article is your go-to resource for understanding the intricate process of transforming raw steel into vital components of modern construction.

We’ll explore:

Introduction to Structural Steel Fabrication

Types and codes for structural steel in the UK

Structural steel fabrication techniques

How to maintain and protect structural steel

Structural steel design & fabrication FAQs

Whether you’re a seasoned professional or new to the field, this guide offers insights and practical knowledge for your structural steel projects.


Introduction to structural steel fabrication

What is structural steel fabrication?

Structural steel fabrication is the process of cutting, bending, and assembling steel into high quality structures and frameworks used in construction.

This involves transforming raw steel into specific shapes and components, such as beams, columns, and trusses, through various techniques like welding and machining.

Essential in creating the skeleton of buildings and infrastructure, it combines precision engineering and skilled craftsmanship to ensure strength, durability, and safety.

The process is guided by design specifications and often incorporates various grades of steel, each chosen for its unique properties to suit the specific demands of the construction project.

What is structural steel used for?

Structural steel fabrication can be used to create a wide variety of structures and components, including:

This versatility makes structural steel fabrication a fundamental process in modern construction and engineering.

When not to use structural steel

It’s important to understand the structural steel shouldn’t be used for every type of construction project – it doesn’t tend to be suited to the below:

  • High corrosion environments: In areas with high moisture or corrosive chemicals, unless adequately protected, steel can corrode. For example, on an oil rig where the sea salt can hasten the corrosion of the steel.
  • Budget constraints: Steel can be more expensive than other materials like wood or concrete, especially with added costs for fireproofing and corrosion protection.
  • Design limitations: For certain architectural designs requiring extensive curves and non-linear shapes, steel might not be as suitable as other more malleable materials.
  • Thermal conductivity: Steel conducts heat, making it less ideal in situations where maintaining consistent internal temperatures is crucial, unless properly insulated.
  • Earthquake-prone zones: In areas with high seismic activity, the steel might need to be made to withstand the shuddering from earthquakes.

What are its advantages?

The main advantage of structural steel lies in its high strength-to-weight ratio.


Grade of Structural Steel Typical Yield Strength (MPa) Density (kg/m³) Strength-to-Weight Ratio (kN·m/kg)
ASTM A36 250 7850 31.85
ASTM A572 Grade 50 345 7850 43.95
ASTM A992 345-450 7850 43.95 – 57.32
ASTM A588 345 7850 43.95
EN S355 355 7850 45.22


To put this into context, let’s consider that 1 kiloNewton is roughly equivalent to the weight of 100 kilograms (about 220 pounds) on Earth due to gravity. So, a 1 kg piece of ASTM A992 steel could theoretically support a weight of approximately 4,395 to 5,732 kilograms per metre length under optimal conditions.

In practical terms, this high strength-to-weight ratio means that structures like skyscrapers, bridges, and large stadiums can be built with relatively less steel, making the structures lighter and more cost-effective, while still maintaining the necessary strength and safety. This capability is crucial in modern architecture and construction, allowing for the creation of taller, more expansive, and innovative designs.

This quality allows for the construction of large, robust structures while using less material, making it cost-effective and efficient.

Other advantages

Structural steel’s strength ensures durability and resilience, capable of withstanding heavy loads and environmental stresses.

Its lightweight nature also simplifies transportation and installation, reducing overall construction time and costs.

This combination of strength, efficiency, and versatility makes structural steel a preferred material in various construction and architectural applications.

What is structural steel made from?

Structural steel is primarily made from:

Iron: The fundamental base element.
Carbon: Added for strength and rigidity.
Additional elements: Include chromium, nickel, manganese, and silicon for enhancing properties like its durability, flexibility and corrosion resistance.

How is it made?

Structural steel is made through a multi-step process:

Iron ore processing: Iron ore is smelted to produce raw iron.
Carbon addition: Carbon is added to the iron to create steel, enhancing its strength and hardness.
Alloying: Elements like manganese, chromium, and nickel are added for specific properties like durability and corrosion resistance.
Forming: The steel is then cast into initial forms and shapes.
Rolling: It undergoes rolling to achieve the desired thickness and shape.
Cooling and finishing: Finally, the steel is cooled, cut, and finished as per requirements.


Types and codes for structural steel in the UK

Types of structural steel

Structural steel comes in various types, shapes and sizes including:

Carbon steel: Common, with high strength and versatility.
High-strength low-alloy (HSLA) steel: Enhanced strength and better weather resistance.
Weathering steel: Known for corrosion resistance making it ideal for outdoor use.
Tool steel: Hard, resistant to abrasion and used in high-stress applications.

Codes for structural steel

Codes around structural steel within the UK are set for several key reasons:

Safety: Codes support to ensure the safety of buildings, structures and their occupants. They help prevent accidents and failures by setting minimum standards for design, materials, and construction practices.
Standardisation: They provide a standardised approach to design and construction, which helps cooperation and understanding among different professionals and stakeholders in a project.
Quality assurance: By adhering to codes, builders and engineers can ensure a certain level of quality and performance in their projects.
Legal and regulatory compliance: Codes often have legal backing, making compliance mandatory. This helps in maintaining uniformity in construction practices and ensuring that all structures meet basic legal requirements.
Innovation and best practices: They evolve over time, using new research, technologies, and methods. This encourages innovation while upholding best practices in the industry.

UK Regulations for Structural Steel

In the UK, structural steel regulations include:

BS EN 1090: Mandatory for fabrication and assembly, focusing on safety and quality of the building material.
UKCA marking: Replacing CE marking post-Brexit for product safety and compliance.


Structural steel fabrication techniques

How is structural steel fabricated?

To fabricate structural steel, our process at CSM typically involves several specialised techniques and stages:

Welding: Skilled teams use various welding methods, including Metal Inert Gas (MIG), Metal Active Gas (MAG), Tungsten Inert Gas (TIG), and gas welding and brazing. These techniques are crucial for joining steel parts securely for both industrial and commercial applications.
Bending and forming: These processes shape the steel into required forms. Using tools like hammers, tap and die sets, powered hammers, and press brakes, metalworkers can manipulate steel from 1mm to 4m in length. This allows for precision in creating bespoke structures as per project specifications.
Finishing: This stage involves applying necessary finishes for aesthetics or safety, ensuring the final product is well-assembled and up to standard before leaving the factory.
Additional processes: These include stamping, drilling, hole punching, and grinding and polishing, further refining the steel parts.
Fabrication & erection: After fabrication, the steel structures are transported and installed as part of the building project.

Each step is critical in ensuring the structural steel is fabricated to meet the high standards of safety, functionality, and aesthetics required in construction projects.

What is structural steel detailing?

Structural steel detailing is the process of producing detailed drawings and plans for steel structures.
These drawings include:

  • Layouts
  • Dimensions
  • Connections
  • Fabrications details
  • Our detailers ensure all components fit together correctly as per your design specifications.


How to maintain and protect structural steel

Do you need to paint structural steel?

Painting structural steel is not always a necessity, but it can be beneficial in certain situations. Here’s when and why you might consider painting:

Corrosion protection: In environments prone to moisture or chemicals, paint acts as a barrier against rust and corrosion.
Aesthetic purposes: Paint can enhance the appearance of steel structures, offering a wide range of colours and finishes.
Fire protection: Certain types of paint provide fire resistance, adding an extra layer of safety.

However, whether to paint structural steel depends on the specific requirements of your project, environmental factors, and intended use.

Preventing corrosion

To protect structural steel from corrosion, at CSM, we may use any of the following methods depending on what project your steel is intended for:

Painting: Applying protective coatings that act as a barrier against moisture and chemicals.
Galvanising: Coating the steel with a layer of zinc for long-term protection against rust.
Stainless steel: Using stainless steel in environments prone to corrosion, as it contains chromium that offers natural resistance.
Weathering steel: Choosing weathering steel for outdoor structures, as it forms a stable rust-like appearance that doesn’t corrode further.
Regular maintenance: Conducting inspections and touch-ups to catch and address any signs of corrosion early.

Maintaining the steel

To ensure the longevity and safety of structural steel, regular maintenance is crucial. Here’s how you can maintain it effectively:

Routine inspections: Regularly check for signs of damage, corrosion, or wear and tear. Pay special attention to joints and areas prone to water accumulation.
Cleaning: Keep the steel surfaces clean from debris, dust, and other corrosive materials. Gentle cleaning with appropriate agents is recommended.
Corrosion control: Look for rust spots or corrosion. Apply protective coatings like paint or galvanising as needed.
Repairs: Address any structural damage immediately. Small issues can escalate if left unattended.
Environmental considerations: In harsh environments, increase the frequency of inspections and maintenance.
Professional assessment: Periodically have a structural engineer or a professional inspect the steel structures to ensure structural integrity.

Does it need to be fireproofed?

Yes, fireproofing structural steel is often necessary, especially in buildings and structures where fire safety is a concern. Here’s why:

Heat Resistance

Steel loses strength when exposed to high temperatures, which can compromise structural integrity.
Structural steel begins to lose its integrity at temperatures around 400°C (752°F). At this temperature, steel starts to weaken, and its load-bearing capacity decreases.
The critical temperature, where steel loses about 50% of its strength and becomes a major safety concern, is typically around 540°C (1004°F).
It’s important to note that the exact temperature can vary depending on the specific grade of steel and its properties.

Building codes

Many building regulations and codes mandate fireproofing for structural steel in commercial and residential buildings.
Methods of fireproofing:

Spray-on fireproofing: Applying fire-resistant coatings that expand when exposed to heat, insulating the steel.
Intumescent paints: These swell when heated, forming a protective char layer.
Board fireproofing: Encasing steel in fire-resistant boards.


Structural steel design & fabrication FAQs

How to read steel structure drawings?

Understanding how to read structural steel drawings can help you to design and plan your project.

  1. Understand symbols and notations: Familiarise yourself with common symbols and notations used in structural drawings. Here are some of the most common ones:
    Symbol Type Description and Example
    Beam Symbols Represent beams; a rectangle with a dashed line inside might symbolise an I-beam.
    Column Symbols Similar to beams but may include additional notations for features like base plates.
    Weld Symbols Indicate type and size of welds; e.g., a flag symbol represents field welds.
    Bolt/Nut Symbols Show bolt/nut locations; circles with an ‘X’ inside could represent bolts.
    Material Symbols Different hatch patterns or letters indicating material types, like “A” for aluminium.
    Detail Symbols Triangles or other shapes pointing to detailed views or sections.
    Reference Marks Alphanumeric codes linking to other details or sections in the drawings.
    Dimension/Elevation Symbols Lines with numbers indicating lengths, heights, and distances.
    North Arrow An arrow labelled ‘N’ showing the structure’s orientation.
    Door/Window Symbols Outlines or blocks indicating the placement of doors/windows in the structure.
  2. Study the dimensions: Examine the detailed dimensions provided for each steel component.
  3. Review connection details: Pay attention to how different steel pieces are connected.
  4. Check material specifications: Look for specifications of steel grades and other materials.
  5. Refer to the notes section: Often contains crucial information about the fabrication and assembly process.

What is structural steel fabrication drawing software?

Structural steel fabrication drawing software is specialised CAD (Computer-Aided Design) software used to create detailed 3D models and drawings of steel structures, facilitating accurate fabrication and assembly.

How to calculate the weight of structural steel?

  • Use density formula: Multiply the volume of the steel section by its density (approximately 7850 kg/m³ for steel).
  • Refer to steel tables: Steel weight tables provide weights for standard sections.

What is PFC?

PFC stands for Parallel Flange Channel, a type of steel beam with parallel flanges, used for columns, beams, and framing.

What is UB?

UB refers to Universal Beam, a beam with an ‘I’ or ‘H’ shape cross-section, widely used in construction for structural support.

Do you have a structural steel project in mind?

If you have a project in mind, get in touch with the CSM team today. We offer a wide range of bespoke structural steel fabrication services.
We’d be happy to talk to you about your requirements and provide you with a no-obligation quote.

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