Piggybacking in stud welding is a specialized technique used when project constraints prevent single, long studs from being welded directly to the base material. In stud welding, piggybacking refers to welding one stud on top of another headed stud, creating a stacked or extended single piece. 

This method is commonly used in structural steel fabrication, precast concrete embeds, and industrial construction where spacing, material limitations, production considerations, or building codes make traditional studs impractical or not up to standard. 

How JSW Does Piggybacking on Stud Rail Assemblies 

When taller stud rails are required, we “piggyback” weld our JSW PSR studs on top of a headed concrete anchor to achieve the required height. When piggybacking studs, JSW uses the stud welding process to attach the PSR (Punching Shear Reinforcement) stud to the top of the headed concrete anchor. This is the same process that we use to attach the PSR stud to the base rail. The stud welding process gives us a full penetration weld in seconds. In each case It is strong enough to cause the stud stem to yield in a tensile test. Thus, the weld is stronger than the materials it is holding together. 

The use of this piggybacking method does not diminish the anchorage of a stud rail, and in some cases, it is even required by code commentary to be done this way.   

Why Piggybacking Is Used 

Piggybacking in stud welding is typically used when: 

• There are limitations with cold heading machines used to make the studs 
• A project’s single stud length exceeds code specifications 
• Existing studs need to be extended to meet design elevations 

By using piggybacking, contractors can maintain structural intent while adapting to real-world fabrication challenges and building guidelines. 

Relevant Code Related to Piggybacking 

American Concrete Institute’s code 318-19; 25 – 22.6.6.2b points out that the shear strength of large concrete slabs may be compromised if single studs longer than 10 in. are used. This is where piggybacking comes in the suggested code commentary. When you piggyback headed shear studs, it creates an intermediate head that helps to further anchor the stud and prevents slippage of the concrete. 

 

Key Considerations for Piggybacking 

Although piggybacking is an effective solution, it must be engineered and executed correctly. Heat input, stud alignment, and weld quality are especially important, as piggybacking changes how loads are transferred through the stud assembly. 

Not all applications are suitable for piggybacking, and it should always comply with: 

• Approved welding procedures 
• Project specifications 
• Applicable building codes and standards 

Inspection and testing are critical to ensure piggybacked studs perform as intended under load. 

 Piggybacking in PSR stud rails offers a practical and flexible solution for complex construction and fabrication scenarios. When properly designed and installed, piggybacking allows projects to overcome project limitations, meet schedules, all without compromising strength or performance. As with any specialized welding technique, proper planning, engineering approval, and quality control are essential for success.