Resistance welding variants — identifying seam welding Seam welding is best described as a __________.

Introduction / Context:
Resistance welding encompasses spot, seam, and projection welding. Seam welding is widely used for leak-tight joints in thin sheet (e.g., fuel tanks, drums) by rolling wheel electrodes that make a continuous line of overlapping nuggets.

Given Data / Assumptions:

• Wheel electrodes deliver repeated current pulses as the work advances.
• Workpieces are overlapped sheets of suitable conductivity and thickness.
• The question compares seam welding to other resistance/arc processes.

Concept / Approach:
Spot welding forms individual nuggets between electrodes. Seam welding turns this into a continuous or closely spaced series by using wheel electrodes and timed current pulses, producing an essentially continuous seam. Projection welding uses localized projections; SMAW is an arc process, not resistance welding.

Step-by-Step Solution:
Identify the hallmark of seam welding: rotating wheel electrodes and overlapping nuggets.Relate the outcome: a leak-tight or continuous joint along the weld path.Choose the option describing a continuous spot-weld sequence.

Verification / Alternative check:
Process data sheets describe lap-seam welding schedules with current-on/current-off timing (intermittent or continuous) to control nugget overlap and heat input.

Why Other Options Are Wrong:
Projection welding is multi-spot at raised embossments; SMAW is an arc process; butt forging of round bars is a different resistance welding variant (flash/butt welding); laser keyhole is unrelated.

Common Pitfalls:
Insufficient overlap causing leaks; overheating leading to burn-through; misalignment of wheel electrodes creating inconsistent nugget formation.

Final Answer:
continuous spot welding process producing an overlapping series of nuggets