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What Is Seam Welding? Process and Applications

Apr 19, 2024

seam welding

Seam welding is a powerful way to fuse metal sheets into one solid piece with a strong, continuous seam. It uses special rollers and electric current to make welds that are airtight and watertight.

In resistance seam welding, the metals get hot and join together when an electric current runs through them. This current creates heat because of the metal's natural resistance. Getting the amount of current right is crucial for a good quality weld.

This method is especially important for making things like car fuel tanks and radiators, where leaks could be dangerous. Want to know more about how seam welding works and why it's so reliable? Keep reading to see how it's shaping the products we use every day.

Fundamentals of Seam Welding

Seam welding, a subset of resistance welding, is essential when you need a durable, continuous weld along a seam. It fuses metal sheets efficiently, useful in industries where hermetic sealing is critical.

Seam welding is a method for joining two or more layers of metal using heat generated from electrical resistance and mechanical pressure.

The process results in a continuous seam of welded material, creating a tight, leak-proof joint.

The technique is ideal for materials such as steel, stainless steel, aluminum, and other metal sheets that require a durable bond over a continuous length.

Learn more about metals in our guide: Different Types of Metal Used in Welding

Components and Materials

Key components in the seam welding process include:

  • Electrode Wheels: These are typically made from copper due to its excellent electrical and thermal conductivity.
  • Metal Sheets: The sheets or workpieces being welded together can vary in thickness and material, including but not limited to steel, stainless steel, and aluminum.
  • Welding Electrodes: Their material composition, often copper or copper alloys, is crucial in facilitating the welding process by concentrating the current.

Materials commonly welded using this process are metal sheets that differ in thickness and conductivity. The choice of materials for both the components and the workpieces being welded significantly affects the efficiency and quality of the seam weld.

Thickness Range for Seam Welding

Seam welding is suitable for a variety of thicknesses ranging from very thin sheets, such as 0.1 mm, up to thicker plates around 2.5 mm. The ideal range can depend on the material being welded and the specific welding equipment used. For metals beyond this thickness, other welding techniques might be more appropriate to ensure penetration and a strong weld.

The Seam Welding Process

Your understanding of the seam welding process is improved by recognizing the steps involved:

  1. Preparation: Your metal sheets must be clean and properly overlapped.
  2. Welding Setup: The workpieces are placed between electrode wheels, applying both pressure and electrical current.
  3. Heat Generation: As electrical current passes through the workpieces, the electrical resistance generates heat, causing localized melting, known as fusion.
  4. Formation of Seam Weld: The roller electrodes rotate to create a series of overlapping spot welds, forming a continuous seam.
  5. Welding Speed: Your control of the welding speed affects the quality and appearance of the weld. It is adjusted depending on the material and thickness.

Throughout the process, the importance of pressure and electrical resistance cannot be overstated, as they directly influence fusion and the integrity of the continuous weld.

Techniques and Variations for Seam Welding

Seam welding as a joining process allows for the creation of sturdy, hermetic seals along continuous or intermittent seams. This technique evolves through various methods, each with its specific applications and advantages.

Also read: Different Types of Welds and Joints in Welding

Resistance Seam Welding

Resistance seam welding, your go-to for producing continuous welds, uses a pair of roller electrodes.

This welding method applies consistent heat and pressure to weld overlapping sheets of metal. Here's what you need to know:

  • Principle: A current is passed through the metal sheets, and the resistance in the material generates the heat required for welding.
  • Applications: You'll find resistance seam welding being critical in industries producing oil drums, radiators, and fuel tanks, providing uniform and robust seals.
  • Benefits: It minimizes the heat-affected zone and distortion of the metal, offering high levels of strength and durability.

Learn more about resistance welding here: What is Resistance Welding?

Friction Seam Welding

In friction seam welding, the heat generation is mechanical, coming from the friction between the workpieces. Dive into the specifics:

  • Procedure: Your workpieces are rubbed together with a rotary motion while under pressure, generating the heat needed for welding.
  • Advantages: This method controls heat input effectively and can join even dissimilar metals, a feat not easily achievable by conventional welding methods.

Other Seam Welding Methods

Beyond the conventional, there are specialized seam welding processes to meet various industrial requirements:

  • Laser Seam Welding: Offers high precision by focusing a laser beam to the seam area. It's a go-to for aerospace and medical equipment due to its fine control and clean results.
  • Stitch Welding: Resembles resistance seam welding but with intermittent spots rather than a continuous seam, similar to the way a sewing machine stitches fabric.

Advantages and Benefits of Seam Resistance Welding

Resistance seam welding, a sophisticated manufacturing technique, confers a multitude of benefits tailored to fulfill industrial requirements. Here are some key advantages:

  • Automation: You can fully automate the process, which significantly enhances efficiency and productivity. This attribute makes resistance seam welding a linchpin in high-volume manufacturing environments where time and consistency are of the essence.

  • Efficiency: With its continuous welding capability, resistance seam welding yields an efficient production line. It reduces the time for repetitive tasks and leads to higher throughput.

  • Consistency: Unlike manual welding, which may be plagued with variabilities, resistance seam welding ensures consistent quality. Because the parameters can be tightly controlled, each weld is uniform, contributing to the reliability of your product.

  • Durability: Resistance seam welding is renowned for creating airtight and watertight welds that offer enhanced durability. This feature is particularly crucial in applications such as automotive fuel tanks and radiators where leak-proof seals are non-negotiable.

Challenges and Limitations in Seam Resistance Welding

Seam welding, particularly resistance seam welding, offers several advantages but it also has its own set of challenges and limitations that you need to be aware of before deciding if this method suits your project.

Common Disadvantages

  • Distortion and Warping: Due to the intense localized heat, there can be a distortion of the metal sheets you're working with, leading to warping.
  • Porosity and Incomplete Fusion: These defects can occur during the welding process and lead to a weak seam.
  • Equipment Cost: The initial investment for resistance seam welding machinery can be considerable.
  • Need for Skilled Operators: Efficient use of this equipment generally requires skilled operators, which increases labor costs.

Handling Precautions

  • Safety Considerations: Always ensure you're complying with safety standards, including using proper protective equipment to prevent injury from sparks or heat.
  • Precaution Against Defects: Consistent monitoring of the welding parameters can help in reducing the occurrence of defects such as porosity or incomplete fusion.

Applications and Uses of Seam Welding

Seam welding, specifically resistance seam welding, is a process you'll find pivotal in various industries due to its ability to create long, continuous welds on metal sheets. This technique is valued for its robustness and precision in producing airtight and liquid-tight joins, which are essential in numerous applications.

Industrial Applications

In the aerospace industry, resistance seam welding is vital for constructing aircraft components.

Your interest here might be in how it joins thin metal sheets—often aluminum—to form parts like wings and fuselages, as well as fuel tanks. The reliability of the welds contributes to the overall safety and performance of the aircraft.

The construction industry and automotive industry also benefit greatly from resistance seam welding.

In construction, it's used for making metal tanks and radiators, where long-lasting, leak-proof seals are non-negotiable. For automotives, efficiency in manufacturing is key, and this type of welding is utilized for parts like exhaust systems and the structural integrity of car bodies.

Common Products

You encounter products made with resistance seam welding more often than you might realize.

Everyday items such as cans, refrigerators, and various types of containers are frequently constructed using this welding technique due to its efficiency and strength.

Additionally, resistance seam welding is indispensable in creating oil transformers, with manufacturers relying on the process to ensure that their products can stand the test of time and demanding conditions.

Technical Aspects of Seam Welding

When considering the technical aspects of resistance seam welding, focus on optimizing the conditions under which the weld is performed and the specific materials at play. These factors are critical in achieving a high-quality seam weld.

Optimizing Weld Conditions

To ensure the integrity of your seam welds, you must fine-tune several parameters:

  • Welding Speed:
  • Adjusting the speed is essential to create a consistent joint.
  • Too fast may lead to defects; too slow can result in excessive heat input and deformation.
  • Weld Current:
  • This directly affects the quality of the weld, as inadequate current may result in weak welds, while too much can cause overheating and damage to the workpiece.
  • Electrode Force:
  • The right amount of force must be applied by the electrodes to ensure sufficient contact resistance and joint strength without compromising the metal's properties.
  • Heat Input:
  • Controlling the amount of heat input is key to avoiding alterations in metal microstructure which can weaken the weld.

Table: Optimal Weld Parameters




Welding Speed

The rate at which the weld is completed along the joint.

Affects weld consistency and heat distribution.

Weld Current

The electrical current used in the welding process.

Determines the strength and quality of the weld.

Electrode Force

The pressure applied by the welding electrodes.

Ensures appropriate contact resistance and joint strength.

Heat Input

The amount of thermal energy introduced to the workpiece during welding.

Influences metal microstructure and overall weld integrity.

Material Considerations

Your choice of material significantly impacts the effectiveness of seam welding:

  • Thickness: The thickness of the metals you are welding must be matched with the correct welding parameters to ensure a strong weld without damage.

  • Metal Type: Resistance seam welding works well with many metals, including magnesium alloys, nickel, and nickel alloys, each requiring specific settings for optimum weld quality.

  • Diameter and Joint Strength: For tubular or cylindrical items, the diameter influences the apparatus used and the overall joint strength.

  • Metals: Adapt your equipment settings based on the type of metal, adjusting for its specific melting point, thermal conductivity, and alloy composition.

List of Metal Type Considerations:

  • Thickness: Ensures weld penetrates the entire cross-section without excess.
  • Magnesium Alloys: Requires careful heat control to prevent burn-through.
  • Nickel and Nickel Alloys: May necessitate pre and post-weld heat treatments.


Seam welding is all about joining metal sheets together smoothly and securely. To do this well, you need machines you can count on. Arc Captain offers just that—reliable welding products perfect for getting strong, leak-free seams every time. 

Whether you're a beginner or a pro, seam welding has a lot to offer, and with Arc Captain’s best welders and premium tools, it's easier than ever. Ready to try out this handy welding method? Look no further than Arc Captain's lineup for gear that helps make every weld a success.

Frequently Asked Questions

Where is the seam weld?

A seam weld is typically located along the edge where two metal sheets are to be joined. It’s a continuous weld that runs along the length of the seam created by the overlapping edges of the sheets. Seam welds can be found in products like tanks, boilers, and various containers, where a durable, long-lasting joint is essential.

What is the strongest weld pattern?

The strongest weld pattern depends on the application but often includes a groove weld or a combination of weld types to create a multi-pass weld. For seam welding specifically, a continuous pattern is strong as it forms a constant, leak-proof seal along the seam. The integrity of the weld also depends on the preparation of the metals and the precision of the welding process itself.

Is seam welding expensive? 

Seam welding can be costly in terms of initial investment for the equipment, which is typically specialized and designed for industrial use. However, the operation costs can be lower over time due to its efficiency and automation capabilities. When considering the cost, it's important to factor in the savings from reduced labor and the high quality of the continuous welds.

What is the common joint for seam welds?

The most common joint for seam welds is the lap joint, where two pieces of metal overlap and the seam runs along the top edge where they meet. This joint type is preferred for seam welding because it allows the roller electrodes to move smoothly along the seam and create a consistent and strong weld.

Does seam welding make a difference?

Yes, seam welding makes a significant difference in applications where continuous, airtight, or watertight seals are required. It provides a consistent and strong joint that can withstand pressure, which is crucial for containers holding liquids or gases, and it ensures the integrity and safety of the final product.

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