What Is Galvanized Steel and Why Is Welding It Challenging?
Galvanized steel is a type of steel that has been coated in zinc for protective purposes. The zinc coating acts as a protective barrier for the underlying steel and prevents rusting. The coating thickness ranges from 2 to 8 mils (50 to 200 micrometers). However, it can change based on specific needs. The projects I have personally worked on at construction sites, have 3 to 5 mils as the standard thickness for building components. The protective zinc acts as a barrier. It also protects the underlying steel by corroding first.
Welding galvanized steel is a problem because of the different temperatures at which the metals of steel and zinc melt. Steel melts at extremely high temperatures, 2500°F (1370°C), and zinc melts at 787°F (419°C). The high temperature range causes the zinc to vaporize before the steel melts. The vaporized zinc produces toxic zinc oxide fumes. Inhaling these fumes can cause metal fume fever, especially without proper ventilation. It also harms the weld, leading to porosity and weak welds. I’ve seen projects where little ventilation led to weak welds, causing inspection failures. Though removing the zinc layer aides in solving the problem, it also increases cost and time.
Galvanized steel is quite common. It is used in structural beams as well as pipes and storage tanks. It is zinc-coated on most outdoor railings. Such usage requires rust prevention. Fabricators know why they must weld galvanized steel. We require strong welds. Worker safety must also be taken into consideration. The correct way to do it will depend on the specific galvanised steel welding project.
How to Weld Galvanized Steel: Step-by-Step Methods
There are 3 main approaches for welding galvanized steel. The decision is relative to your project. Consider coating thickness, batch size, and the tools you have. In my experience, each method has its own advantages and disadvantages.
Method 1: Removing the Galvanized Coating First
For top-quality welds, especially with galvanized steel over 5 mils thick, this method is for you. It is best for structural applications like bridge work and load-bearing beams since the strength of the weld is crucial. The additional prep time will add to cost, but it is well worth it for stronger welds and less fume exposure during the welding process. I choose this method for critical structural projects.
To start, you will have to grind both sides of the weld area, using a flap disc or a wire wheel to remove at least two inches on both sides of the joint. Continue using the grinder until the coating sits on bare steel. You will notice the zinc layer disappearing and a gray color of steel will show from underneath. You can remove long units with machines, but doing it by hand takes 5 to 10 minutes per foot. Some places use acids, however it is important to crosscheck the safety data sheets of documents and the manufacturers. Following the manual step, you will have to clean the surface using solvents such as alcohol or acetone to scrub any grease or oil off the surfaces. I usually ensure to clean and check the surface before welding, since the dirt will cause corrosion.
Welding is not to be done within 4 hours because it will expose the iron and form rust on the area. If rust occurs, you will have to clean that area again before welding.
Method 2: Welding Through the Coating with Precautions
Coating penetrable welding works on coatings as thin as 3 mils. Therefore, it is an ideal process for small and quick jobs which do not require heavy preparation activities. I personally do quick fixes on outdoor railings using this technique as for welding, the coating simply burns off. I use this method for ventilation, but I avoid it for critical welds. Zinc fumes can weaken the welds and are hard to control.
When welding through the coating, adjust your settings by increasing the 6500 setting by 10 to 15 percent. This helps burn through the zinc layer. For MIG welding, use 130 amps instead of 120 for a quarter-inch steel. Also, increase the voltage to 22 volts instead of 20 volts. 6500 Move faster to reduce heat input 6500 and aim between 8 to 6500 10 inches per minute. This helps 6500 prevent burn through. Use a 6500 slightly larger 6500 wire diameter which helps 6500 with penetration. I have a notebook with all 6500 my settings for 6500 multiple coating thicknesses to save 6500 time for repeat jobs.
It is crucial to follow safety protocols when welding through coating and using local exhaust with 4000 CFM or more. Position the Exhauster Vent at least 3ft away from the user. Use a PAPR or supplied-air respirator. Regular breathing air isn’t enough for this method. The burnt zinc fumes are more intense when the burn is active. I always test airflow before any initial work. I use a smoke test which determines if the exhaust vent is functioning properly.
Method 3: Using Specialized Welding Techniques
Pulse MIG welding is great for controlling heat input. This makes it a good choice for cost-effective welding while reducing zinc vapor concentration. Some welders use cold metal transfer processes. These methods create less heat in the base metal. This lowers fume concentration. As a result, it helps prevent poor-quality welds, unlike higher temperature methods. These methods and advanced tools cost more, but they are a better choice for smaller units. They prioritize safety and quality, making them the more economical option.
Pulse MIG systems start at $2,500. Entry-level models go up to over $5,000. Advanced systems begin at $8,000. These systems need pulse capability, which also needs certain wire and gas combinations. This method suits high-volume shops. Smaller ones usually stick to standard methods. Check your volume before investing. Doing so reduces fume problems over time and improves weld quality.
Welding Parameters and Equipment Selection
MIG Welding Settings for Galvanized Steel
MIG welding is very popular for working with galvanized steel because it is fast and allows the operator to have control. The fume control on the wire feeder is very beneficial for most galvanizing projects. It works for many coating thicknesses.
For most jobs, set the amperage from 80 to 150 amps. Use 80 to 100 amps for thin materials under 1/8 inch. For thicker sections up to 1/4 inch, use 120 to 150 amps. About 18 to 24 volts, dependent on your amperage, and argon-CO2 gas set to 75/25 (good with galvanized coatings for welding), about 20 to 25 CFH. Your travel speed should be 6 to 10 inches per minute. Any faster and you risk heat-controlled zinc vaporization.
Be careful about the burn through on thin materials. If you see holes, you need to reduce the amperage. If the surface is not clean, porosity is inevitable. Anti spatter spay is very useful for galvanized coatings.
TIG Welding Settings for Galvanized Steel
TIG welding allows for more controlled precision when working on thin galvanized steel and on more intricate designs. It also safer than MIG welding in close confines, because the fume production is much lower.
Set the range on the welding machine between 60 and 120 amps according to the thickness of the materials. For sheet metal underneath 1/16 of an inch, use between 60 and 80 amps. For materials up to 1/8, use 100 to 120 amps. Use pure argon gas between 15 to 20 CFH, and a travel speed of 2 to 4 inches per minute. Slower travel speeds help to control the weld pool, which is crucial for successful welding.
Tungsten contamination is especially prevalent with coated materials such as galvanized steel. Use a dedicated tungsten grinder. Keep separate tungsten for different materials. This helps avoid cross-contamination.
Stick Welding (SMAW) Settings
Stick welding is good for galvanized steel outdoors. It handles wind better than gas-shielded methods. This is the method of choice for field repairs due to its reliability and portability.
Set the range for stick welding between 90 and 140 amps. Use 90 to 110 amps for the 1/8 inch rods and 120 to 140 amps for the 5/32 inch rods. Voltage with E7018 or E6013 electrodes is stable between 22 and 28 volts, and the travel speed is 4 to 6 inches per minute.
Electrode sticking is more common with galvanized coatings, so reduce the lower limit of the amperage range. Slag removal requires more care than usual because the zinc coating can mix with the slag.
Equipment Selection Guide: What You Need to Weld Galvanized Steel
Equipment choices include factors impacting weld quality and safety of the workers. Substandard projects have plagued my past and it is much easier to simply invest in quality tools rather than having to start over.
Basic MIGs start around \$400 and professional units cost between \$1,200 and \$3,500. Look for units that have adjustable wire feed speed for the best outfitting. TIG welders start from \$800 and units of professional grade cost between \$2,500 and \$5,000. Stick welders are quite affordable. Entry models cost between $200 and $400. Professional-grade units range from $600 to $1,200. Your primary applications will determine the choice.
You need various safety equipment, including:
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PAPR systems cost between $500 and $1,500.
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Supplied air systems priced from $800 to $2,000.
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Professional-grade systems starting at $300 and going up to $3,000.
These should be considered as part of your initial budget.
Removing coating adds between \$50 and \$100 to the hour cost of labor. Direct welding that involves safety equipment ranges from \$500 to \$2,000. Investement in specialized equipment between \$2,500 and \$8,000 is needed. Calculate your volume to figure the payback period.
Safety First: What are the Risks of Welding Galvanized Steel
Welding galvanized steel can be dangerous. OSHA guidelines in 29 CFR 1910.252 highlight the need for local exhaust ventilation.
Use the right PPE:
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Auto-darkening helmet
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PAPR or supplied air respirator
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FR clothing
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Leather gloves
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Safety boots
Also, set local exhausts between 4-6 ft. Use 2000 CFM for light work and 4000 CFM for heavy work.
Remember PPE should always be used in tandem with ventilation systems.
Welding Mistakes and How to Progress
Burn Through
Burn Through or Overheating is excessive heat when the amperage is too high or the travel speed is set too low. When Zinc gets too hot, it vaporizes at about 787°F. This can create holes in materials that are otherwise undamaged during welding. This issue is known as burn-through.
Welding settings should be lowered by 10-15 percent in more standard settings. Increase travel speed to about 8-10 inches per minute. Also, use a smaller wire diameter with thinner materials. This will help reduce heat input.
A glowing, wide weld pool indicates too much heat, which suggests overheating. The diameter of the wire being used should determine the pool; anything larger generates too much heat. Listen for burning or popping sounds. If you hear them, adjust the settings right away. Otherwise, the correct settings won’t take effect, and burn-through may happen.
Inadequate Ventilation
There are a lot of whiffs that a welder can take. Some of these can be more harmful than others. Concentrated fume of zinc galvanized steel is harmful as it can be lethal. If the weapon are not done with the galvanized steel properly, it can also vent a lot of fume. If the work is done on a larger scale, the fans needed should be 400.
If you see Mr. Z looking like a ghost, it means that the ventilation is not good. If you are able to catch a whiff of bronze, it means that there was not much facility available for the workers. Zombies are like the poster children for bad ventilation.
Wrong Filler Material Selection
Welding a 1000 series to a galvanized piece is tough. The chances of a successful weld are very low. The weld is bound to be porous as it is very soft. If you admire puzzle pieces with 1000 series, it is best to work with a 700 series. If you admire puzzle pieces, it is best to work with a 700 series.
If the welded area is full of bubbles, it means you are working with the wrong filler. If welds are coming with more cracks, it is best to check for the filler.
Real-World Applications and Case Studies
Structural Steel Welding
There was a fabrication shop once that welded two galvanized I-beams on a bridge. The beams connected were 12 inches deep with 5 mils thickness. The work here was crucial for load-bearing needs. The team used grinding techniques to strip the coating from the welds. The prep stage on each beam took around 8 hours. After proper…
All the welds passed the inspection, and the extra prep time saved on rework costs. Investing time in preparation pays off in the end.
Pipe Welding Applications
A maintenance crew needed to repair 4 inch galvanized water pipes that have a thin 2 mil coating. In this case, a repair needed to be done as…
They set up proper ventilation and burned through the coating, and MIG welding at 110 amps was good since the coating burned away clean. Repairs became intact without a single issue…
Lesson: Ventilation becomes crucial during welding operations using the pipes. Thin coating can be directly welded with proper ventilation.
Sheet Metal Projects
A shop fabricated galvanized sheet metal panels using the 14 gauge material that was highly coated at 3 mil. In this case a high volume production…
They began using pulse MIG welding enabling a much better set up. Products during the welding process improved in production speed by around 20 percent.
There was a decrease in quality, there was a drastic increas in production speed. Investing in the pulse equipment became helpful very quickly. The phrase illustrated suggests: techniques work for high volume operations.
Cost Analysis: The Feasability of Welding Galvanized Steel
Welding galvanized steel involves greater expenses than welding regular steel. This is why we look at the galvanized steel welding cost breakdown.
Removing the coating takes $50 – $100/hour of labor, plus $20 – $40 in other materials per project.** Direct welding requires $500 – $2,000 in safety equipment. Specialized techniques investments span $2,500 – $8,000, so you better calculate your annual volume to determine which method is worth adopting.
ROI depends on project volume. Direct welding is optimal for low volume projects. In the case of medium volume, coating removal equipment should be used, while for volumes over 500 pieces a specialized technique should be used. You should calculate your payback period based on your specific usage.
Focus on the situation you are in: for one-off projects coating removal works, while regular production needs specialized techniques. In this case you should assess Total Cost of Ownership over the minimum up front cost.
Regulations and Standards
OSHA Compliance Checklist:
Welding safety is covered in the OSHA standard 29 CFR 1910.252, and so is galvanized steel welding. Thus, compliance is necessary at all worksites.
Nebulous Welding and Engineering Ventilation: Standard Operating Procedures
WSOPs must provide good ventilation for hazardous fumes, such as Zinc Oxide Fumes. Local exhaust ventilation should be within 4 feet of the work area. Remember, you must document ventilation aids, as OSHA Inspectors will request proof.
Check your system ventilation cross-check the PPE system for the arm Megablast and the rest of the staff for proper training. Safety folders must be created and compliance records will be checked.
AWS Standards for Welding Galvanized Steel
AWS D1.1 sets welding standards for structural steel, including galvanized materials. You must follow these standards for structural uses.
The standard requires proper joint preparation and sets minimum levels for weld quality. You’ll need to check the minimum levels for your specific application.
International Standards (ISO/EU)
ISO and EU standards are mandatory for international projects. In case you are focusing on Europe, CE marking is mandatory, so make sure you are aware of the targeted territories.
Frequently Asked Questions (FAQ)
Q: Can you weld galvanized steel?
A: It is possible, but safety is key. Zinc coating gives off harmful fumes when welding. So, ensure you have good ventilation and proper breathing devices. The method will depend on the thickness of the coating you have and what your project is.
Q: What are the dangers of welding galvanized steel?
A: It is dangerous if the right steps are not taken. Breathing in zinc oxide fumes can cause chills and fever. Use local exhaust ventilation and appropriate PPE to protect yourself. Along with fever and chills, ventaltion and adequate PPE is necessary respiratroy trouble will increase.
Q: What happens if the welding of galvanized steel is done without the coat of the galvanized steel?
A: Reinforced fume zinc welding will be of more use. If welds are more porous weaker ventilations are stronger. While welding coating is more used for zinc fume blasting.
Q: What is the most efficient way of welding against galvanized steel?
A: While most of the time she’s used for a MIG, we must not forget how TIG has its strong points in thin and detailed materials. Also, stick welding for most outdoor sites is a strong sibling. While considering outdoor works, the daughter welds need more specific.
Q: Is standard equipment used for welding galvanized steel?
A: Along with welding equipment that happens to be BAT, fume welding that is priced for ventilation that happens to be BAT.
Q: What is the proper process for removing the galvanized coating before welding?
You need to grind the weld area using a flap disc or wire wheel. Remove at least 2 inches on each side. Then, clean the area with solvent to eliminate any grease. Finally, weld it within 4 hours to stop rust from forming.
Q: What is metal fume fever and how do you identify its symptoms?
A: The symptoms occur in a matter of hours. You might experience chills, fever or a headache, and some nausea, along with a Rter chest constriction. This will last anywhere from 24 to 48 hours.
Q: What is the best voltage and amperage for welding galvanized steel?
MIG welding needs 80 to 150 amps based on metal thickness, with 18 to 24 volts. For TIG welding, use 60 to 120 amps and 15 to 20 volts. Adjust according to the setup, of course.
Q: Is it possible to TIG weld galvanized steel?
A: Of course! TIG welding with galvanized steel is pretty straightforward. You have much better control, which means you can produce less fumes than with MIG. Just make sure you clean the tungsten often to avoid it getting contaminated.
Q: How much does it cost to weld galvanized steel in the United States of America?
A: The cost will depend on the method you use. Removing the coating will cost $50-100 per hour. You’ll also spend $500-2000 on safety gear. If you choose advanced methods, expect to pay $2500-8000 for equipment alone.
Q: Which type of filler material do I use for galvanized steel?
Use ER70S‑6 wire for MIG welding down to the sleeve. It handles zinc contamination well. For TIG welding, choose ER70S‑2 filler rod to meet base metal strength needs.
Q: Is it legal to weld galvanized steel in a workshop with no ventilation?
A: No, it is against the law. OSHA—29 CFR 1910.252—requires proper ventilation for hazardous zinc oxide fumes. Local exhaust ventilation is essential.
Q: For how long can zinc fumes be airborne?
A: Zinc fumes will stay without proper ventilation and turn into fine dust. With good ventilation, they disappear right away. With no ventilation, they can linger for hours.
Q: What personal protective equipment do I need for welding galvanized steel?
A: The required personal protective equipment includes:
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Welding helmet
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Flame-resistant coveralls
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Respirators (PAPR or supplied-air)
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Leather gloves
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Protective footwear
Also, ventilation PPE does not replace other PPE.
Q: Is it possible to weld galvanized steel to regular steel?
You can weld galvanized steel to regular steel. Just follow the same steps as for welding galvanized to galvanized. Make sure to observe safety measures for zinc fume protection.
Conclusion:
The project needs a strong focus on safety. That’s clear after careful thought about its many aspects. When choosing a coating thickness method, make sure to have good ventilation. Also, use a certified respirator for safety.
For critical welds, remove the coating. Direct welding is best for quick repairs on thin coatings. Use specialized methods for high-volume production. Each method has its place. Invest in quality safety equipment. The risks are valid as well as the costs. The proper preparation always brings quality equipment and positive results on worker safety.
