A seal weld is a type of weld applied primarily to prevent the passage of fluids, gases, or contaminants—not to provide structural strength. Unlike load-bearing welds, its role is sealing gaps or joints to prevent leaks, improve corrosion resistance, and in some cases, to enable easier cleaning or preparation of a surface for finishing.

Distinguishing Seal Welds from Structural Welds

While both may look similar, a structural weld is designed to carry loads, resist stress, and form part of the load-bearing skeleton of a structure. A seal weld, in contrast, might be cosmetic or functional in a different way, such as forming a barrier against water or corrosive gases.

Where Seal Welds Are Commonly Found

You’ll typically find seal welds in:

• Pipe flanges and vessel covers
• HVAC systems
• Industrial enclosures
• Painted steel components
• Galvanized steel joints
• Heat exchangers