AWS A3.0, Standard Welding Terms and Definitions, defines a seal weld as: “Any weld designed primarily to provide a specific degree of tightness against leakage.” The purpose of a seal weld may be to contain a fluid – either gaseous or liquid. In the mechanical and structural fields, seal welds are used most often not to prevent leakage out of a container, but to prevent entry of a fluid into a space where some type of harmful behavior, often corrosion, is expected to occur.

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Conclusions
Seal welds can perform an important function both in containing fluids, and in precluding the entry of fluids into regions where harmful effects can result.

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