Bolted vs. Welded Connections
CSI Division 05, Metals
The two primary methods of joining structural steel members in the field, high-strength bolts torqued to a specified tension, or field welds joining pieces directly, each with different inspection methods, cost, and schedule implications, and a single project typically uses both depending on the connection.
Why it matters
A bolted connection can be visually and mechanically verified relatively quickly by checking bolt tension, while a welded connection's actual quality is hidden inside the weld itself and requires nondestructive testing, such as ultrasonic testing, to verify, which affects both inspection cost and schedule.
On a real project
A structural engineer specifies bolted connections for a steel frame's repetitive beam-to-column connections, since they can be erected and inspected quickly, but calls out field welds at a few specific moment connections where the design requires a continuous, rigid joint bolts alone can't achieve.
Who this matters most to
An Ironworker makes bolted connections in the field. A Welder makes field welds, a distinct skill requiring its own certification. A QA/QC Inspector verifies both, using different inspection methods for each.
Where this goes wrong
A crew substitutes field welds for several connections the structural drawings specified as bolted, to save time sourcing the correct bolts. The substitution isn't caught until the fabricator's own steel detailer, preparing as-built documentation for the closeout package, notices the site photos don't match the approved connection design, triggering an engineering review before the connections can be accepted or have to be redone.