People have crossed waterways and other difficult spans in different ways through the centuries. Durability wasn’t as important back in horse and buggy times, but today’s bridges must be strong. Thankfully, something else changed besides the type of traffic – the 1880s saw the introduction of steel.
Steel did have limitations in the beginning, however. It wasn’t until the 1930s and the development of stud welding that people could use steel to accomplish new feats. Stud welding makes bridges sturdier and permits modern designs. If you want to earn a bridge welder salary you must learn how stud welding works.
What is Stud Welding?
Stud welding, or more accurately, drawn arc stud welding, is a process unlike spot and resistance welding. Rather than using electric current and high pressure, stud welding uses an electric arc. There are two stud welding processes that can be used – capacitor discharge (CD) and arc stud welding.
- Capacitor discharge. This process is semi-automatic and ideal for working with small diameter, shorter studs, and thin materials. Typically, people use this type of welding for sheet metal, not for bridges.
- Arc stud welding. Ideal for use with a variety of materials of nearly any size, people use arc stud welding for bridges and other structures.
What are the Benefits?
The beauty of this process is that various materials can be used and the fastener is attached without marring the other side of the workpiece. This makes it aesthetically superior. Stud welding is also more secure and won’t work loose, which is essential for bridges, because of the constant vibration of traffic. Another benefit of stud welding is that it is easy to learn. Even a novice welder should pick up the skill readily.
How to Join a Bridge Crew
Qualification approval for proficiency is necessary before acceptance on a bridge project. This usually involves completing 10 studs in the diameter and position that will be needed. The welder would also be using the same equipment and materials. These are tested for failure by torque testing, bend tests, and other methods.
The visual result is also important. Cold weld, hot weld, or stud hang-up results will disqualify the welder. The visual inspection is looking for even flash, a shiny hue, proper flash height and after-weld length, as well as other guidelines for the project.
How Stud Welding is Used on Bridges
There are many places on bridges that stud welding is used. One important area is connecting the bridge at the ends. You may have noticed that when you drive onto a bridge, you hear a gentle “thump, thump” noise. A metal plate that extends between the bridge and the road causes this. This metal expansion joint allows the bridge to contract and expand with temperature changes. On the back of that plate, stud welding holds it in place by anchoring it to the concrete sets.
Stud welding also creates adhesion between other plates and steel to concrete and reinforced mesh. This is part of the steel girder to slab construction process. Sometimes shear connectors welded to the top flanges of the girders are done off-site and shipped to the project. Other shear connectors must be done onsite.
Outlook for Bridge Construction
In 2016, the American Road & Transportation Builders Association (ARTBA) reported that there are 58,495 structurally deficient bridges in the United States. Other reports put that number much higher and note that more than 20,000 of them are “fracture critical.” More than 12% of bridges in some states are in trouble.
The Federal Highway Administration (FHWA) recognizes that nearly twice the current budget is needed to deal with this backlog, with state, federal, and local governments working diligently to increase their bridge investments.
A number of bridges will be replaced as a result. For example, the new Tappan Zee Bridge will span the Hudson River in New York to replace the Governor Malcom Wilson Tappan Zee Bridge, and should be completed in 2018.
In addition, many interstate bridges are being expanded to accommodate more lanes, improving America’s infrastructure. With all this in mind, the bridge welder market should grow 15% from 2010 to 2020.
Other Applications for Stud Welding
As the industry changes, stud welders will continue to be in demand. Currently, stud welders are needed in more than 200 industries. Growth in many of these, including alternative energy markets, assures job growth for stud welders.
Getting stud welding training and obtaining welding certification, such as through the Ironworkers/AWS National Welding Certification Program, will open doors. Some projects hire certified welders only, so your options will be limited to some degree without certification.
For all your stud welding equipment and service needs, turn to Stud Welding & Fasteners, Inc. where “Our word is as strong as our weld.”