The failure did not come from the steel; it came down to a connection detail.
During construction, a design change was made to the hanger rod connection to support the walkways. Instead of a continuous rod running through both walkways, the connection was split into two rods. The minor change doubled the load on a critical connection point. It was not fully reviewed and was not caught in time.
Events like this, along with others throughout the 1980s, played a role in shaping today’s building codes and special structural steel inspection requirements. They reinforced the need for independent verification in the field to confirm that construction aligns with the design.
What This Looks Like on Today’s Jobsites
On paper, everything can look correct. The details are there, the design is approved, and the intent is clear. Once work begins in the field, things can shift. Connection details get adjusted; welds vary, materials change, and the installation does not always match the drawings exactly.
At MTC, we are on-site during construction verifying that the work being performed aligns with project requirements and applicable codes. This includes observing welding, checking bolted connections, and performing nondestructive testing where required. We also identify items that are commonly overlooked during construction, including:
- Welds that do not meet size requirements
- Connections that are not installed as detailed
- Missing or incorrect welding documentation
- Internal defects found through ultrasonic testing
What We are Looking at in the Field
The specifics of what we are doing on-site can vary by projects, but the core of our work comes down to verifying that what is being installed meets both code and the project requirements.
Welding
Welding involves a lot of requirements that are not always obvious unless you are looking for them.
In the field, we verify welder certifications in conformance with AWS D1.1 and review the Welding Procedure Specifications (WPS) being used. From there, we are inspecting welds to make sure they meet both code and project requirements.
That includes looking at fillet welds and groove welds, checking material fit-up, joint preparation, and verifying filler metals. We are also confirming that the work we’re inspecting in the field is done in accordance with the project drawings.
Weld size is another key part of this. Most welds have a required size, and we measure to confirm they meet those requirements. If they do not, the weld may need to be removed and reworked or built to meet the specified size.
Bolting
For bolting, we are working in conformance with AISC and RCSC requirements.
We verify the type of bolt, nut, and washer being used and determine whether the connection is snug-tight or slip-critical. For slip-critical and moment connections, we use torque wrenches to confirm the required kips or torque values are being met.
In the field, we are walking the structure and checking each connection. That includes looking for loose bolts, verifying that faying surfaces are in firm contact, and confirming proper installation of TC bolts by checking that the spline has been snapped off.
We also verify anchor bolts—making sure there is full thread engagement and that bolts are not set below the nut. In some cases, we are also confirming drilling depth and epoxy type to verify everything was installed in conformance with the drawings.
Nondestructive Testing (NDT)
- Magnetic Particle Testing (MT): Detects surface and near-surface defects in ferromagnetic materials
- Dye/Liquid Penetrant Testing (PT / LPI): Identifies surface-breaking defects using capillary action
- Ultrasonic Testing (UT): Detects internal defects and is commonly required for moment connections and complete joint penetration welds when thickness requirements are met
UT is one of the most used methods and plays a key role in identifying internal weld issues before they become larger problems.
Common Issues We Catch
Through our inspections, we regularly identify issues that could impact the structure if left uncorrected.
Common findings include:
- uncertified welders performing work
- incomplete fusion, cracking, undercut, and overlap
- welds that do not meet required size
- loose or improperly installed bolts
- material defects such as laminations
Many of these conditions create stress concentration points that can act as crack initiation sites and lead to fatigue failure under load.
Real-World Impact
Our work has helped identify critical issues in the field that could have
In one case, we were called to inspect a mast arm that had been struck by a vehicle. It was initially believed that the damage was limited to bending and surface-level cracking in the galvanized coating. After performing a visual inspection, we found a seam weld rupture. This type of defect would continue to propagate over time and could have led to failure. The structure was supporting traffic signals over an active roadway, making it a significant safety concern.
On large structural projects, ultrasonic testing (UT) has revealed defects within welded beams. These internal discontinuities could have developed into cracks once the members were placed under load. If left uncorrected, this type of defect has the potential to result in structural failure.
We have also found defects in full penetration groove welds using ultrasonic testing. These types of connections are critical to the overall performance of the structure, and any deficiencies could lead to failure under stress if not addressed.
What Sets MTC Apart
MTC takes a proactive and collaborative approach in the field. Our team works closely with contractors and subcontractors, communicating clearly when issues are identified and helping address them early. This approach supports project progress while maintaining compliance with code and project requirements.
Professionalism, efficiency, integrity, and strong communication are key parts of how we operate on every project.
If you have a project that requires structural steel and special inspections, our team is available to support.
