When designing a steel structure, one of the most critical decisions is how to join the components. The choice between welding and bolting impacts the project’s cost, speed, structural rigidity, and even long-term maintenance.
At Weld Rich & Steel, we utilize both methods depending on the specific requirements of the Ontario Building Code and the site conditions. Here is a technical comparison to help you decide which is best for your construction project.
Welded Connections: Maximum Rigidity
Welding involves fusing two pieces of metal into a single, continuous structure. In structural steel, this is typically achieved through FCAW or SMAW processes.
Key Advantages:
Structural Continuity: Welding creates a rigid connection that distributes loads more uniformly, which is often preferred for high-rise frames.
Aesthetics: Welded joints are sleek and seamless, making them the superior choice for exposed architectural steel, such as custom staircases and mezzanines.
Weight Reduction: Since no gusset plates or heavy fasteners are required, the overall weight of the steel structure can be significantly lower.
Bolted Connections: Speed and Versatility
Bolting involves using high-strength fasteners (typically ASTM A325 or A490 bolts) to connect steel members through pre-drilled holes.
Key Advantages:
Ease of Erection: Bolting is significantly faster for on-site assembly. It requires less specialized equipment than field welding.
Environmental Resilience: Unlike welding, which requires dry conditions and specific temperatures, bolting can be performed in almost any Ontario weather.
Future Modifications: Bolted structures are easier to dismantle, modify, or expand, which is vital for industrial warehouses.
Comparison Table: At a Glance
| Feature | Welded Connection | Bolted Connection |
| Strength | Exceptionally high (fused) | High (mechanical) |
| Installation Speed | Slower (requires prep/cooling) | Fast (torque-and-go) |
| On-Site Difficulty | High (CWB field cert required) | Moderate |
| Inspection | Complex (Visual, NDT) | Simple (Torque testing) |
| Aesthetics | Clean, seamless | Industrial, visible bolts |
The Hybrid Approach: Shop-Welded, Field-Bolted
In modern Toronto construction, the most efficient strategy is often a hybrid:
Shop Welding: We weld complex sub-assemblies in our controlled facility under CWB supervision for maximum precision.
Field Bolting: These assemblies are then transported and bolted together on-site for rapid erection.
FAQ
Does the Ontario Building Code prefer one over the other?
Both are accepted under CSA S16. The choice is usually made by the Project Engineer based on load requirements and budget.
Can you weld over a bolted connection?
This is generally avoided. Combining bolts and welds in the same joint requires complex engineering because they share the load differently.