What is a hermetic weld, and where is it used?

A hermetic weld is a weld that creates a completely sealed joint, preventing the passage of air, moisture, or other gases. This type of weld is essential for applications where environmental isolation is critical, such as in aerospace components, medical implants, electronic enclosures, vacuum systems, and cryogenic storage.

Hermetic welds must be free from defects like porosity, cracks, or incomplete fusion that could compromise the seal over time. Techniques like TIG welding, laser welding, and Friction Stir Welding (FSW) are commonly used to achieve hermetic integrity. FSW, in particular, is known for producing dense, uniform welds with excellent sealing capability—especially in aluminum and other non-ferrous alloys—making it a reliable choice for high-performance, leak-tight applications.