Can You Solder Galvanized Steel? Safety Precautions and Techniques
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Soldering (a method used to connect metal materials together) is useful when building with a mix of durable materials. That is why many construction managers and builders will wonder, “Can you solder galvanized steel?”
The short answer is yes, but it is important to understand what you’re doing before you begin. Galvanized materials are uniquely corrosion-resistant because of their zinc coating. When you choose to damage that coating, you risk hurting the integrity of the materials themselves.
Soldering uses heat to prepare the sections of metal materials before fusing them together. When one of those materials is galvanized, it will affect the zinc coating.
In this article, we’ll help you better understand how to join galvanized steel materials while maintaining their quality.
Soldering: What it Is and How it Compares to Other Methods
On a basic level, soldering galvanized steel works the same way as soldering any other metal. To join the pieces, sections are heated enough to fuse the two materials but not enough to melt them.
The solder used to join galvanized materials is a little different than that used for other metals. When soldering galvanized steel, it is important to choose alloys that contain zinc so they marry well with existing zinc coating.
- To begin the process, one must start with clean materials.
- ASTM A780 specifies cleaning the galvanized steel with a wire brush or light blast cleaning. Afterwards, the steel receives a final wipe down before the application of the flux. A flux helps to further clean the materials and guide the solder.
- After the prep work is complete, the steel must reach 600 degrees Fahrenheit before the solder starts. At this point, the solder forms a strong and tight bond between the two pieces as it melts and joins them.
- Once everything is cool, the area receives a final cleaning and inspection to ensure the zinc coating is still high-quality.
Is It Safer to Solder Galvanized Steel Instead of Welding It?
When compared to other joining techniques, like welding or the use of adhesives, soldering stands out for its lower heat requirements. It also has minimal impact on the structural integrity of the galvanized materials.
Welding galvanized steel poses many safety risks. It involves much higher temperatures to fuse the materials together, which can alter the physical properties of the metal. It is more time-consuming, as you need to remove the zinc coating before welding the steel together. It can also damage the welder, either by splattering molten metal or releasing toxic zinc fumes into the air.
Adhesives don’t use heat and don’t pose the same safety risks as welding. But their bond is only surface-level and may not be as durable in certain environments. This can create serious safety concerns on the construction site.
Soldering is one of the safer ways to repair or join steel materials that are already galvanized. It is both safer for the person doing the work and for the materials themselves.
How to Solder Galvanized Steel Without Causing Damage
The best way to successfully solder galvanized steel is by taking care to follow best practices in each step of the process.
- This starts with proper preparation. The surface needs to be thoroughly clean and free of any dirt, oil, or oxidation. Sanding or using a wire brush can help restore the galvanized steel to a better state, or expose the bare metal if desired to promote better solder adhesion. It’s also important to ensure that the surface is dry and free of contaminants before proceeding.
- Choosing the right flux is another critical step when soldering galvanized steel. Flux is used to clean the metal and prevent oxidation during the heating process, ensuring a strong bond between the materials. For galvanized steel, it’s recommended to use an acid-based flux specifically designed for the material to improve the effectiveness of the solder.
- After preparing the galvanized steel carefully and choosing a flux that is up to the task, it is important to choose the right heating method. A soldering iron or blow torch is the most popular choice, as they can maintain the appropriate temperatures with control. Keeping steady and focused heat on the area being soldered will create a durable and seamless bond without damaging the galvanized protective coating.
- Finally, the soldered pieces need one last cleaning to remove excess flux. Wiping them down with a little water, then drying them completely afterwards, will prevent corrosion.
Common Mistakes When Soldering Galvanized Steel
Not following the steps above can negatively impact the galvanized steel.
- If overheating of the material happens, the zinc coating can sustain damage beyond the solder area and weaken the entire piece of steel.
- Improper cleaning or preparation of the surface can result in poor adhesion of the solder, leading to weak or unreliable bonds.
- Using the wrong type of solder or flux may also compromise the integrity of the connection, causing it to fail under stress or exposure to the elements.
The final strength of the soldered galvanized steel depends on the quality of the soldering process and the materials used. Soldering is most successful when used to join or repair small sections of galvanized materials.
Even when best practices are followed, soldered galvanized materials may not hold up in high-stress situations where the original steel would have performed fine.
Typically, the reason galvanized steel is chosen for a project is for its superior corrosion resistance. When trying to work on the galvanized materials, there is always the potential for the original, unique zinc coating to sustain damage. Soldering is no different, so it must be handled carefully to maintain the integrity of the galvanized materials.
No One Knows Galvanized Steel Like South Atlantic
At South Atlantic, we have decades of experience with galvanized materials. From our own in-house galvanizing service to our robust stock of galvanized steel and rebar to suit many needs, we are your best resource for superior steel construction materials.
Learn more about our pre-galvanized material inventory and how we protect every stage of the shipping process to make sure they arrive at your construction site in perfect condition on time, every time.
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Sources:
American Galvanizers Association, “Zinc-Based Solder,” https://galvanizeit.org/inspection-course/repair/zinc-based-solder
