Leaktight

Leaktight is an adjective used to describe a component, assembly, or system that prevents the passage of liquids or gases under defined conditions. In practice, leaktightness is demonstrated by meeting a specified leak rate or by passing a leak test under particular pressures, temperatures, and durations. The term is often used interchangeably with hermetic or watertight in common language, but in engineering contexts it emphasizes the absence of leaks within the tested regime rather than absolute impermeability in all circumstances.

Leak rate is typically expressed in units such as mbar·L/s or Pa·m3/s, and depends on the test method. Common tests include pressure decay, vacuum decay, and helium mass-spectrometry leak testing. Qualitative methods such as bubble testing are used for quick checks but are not quantitative. Leaktightness is always specified for the worst-case operating conditions.

Applications include leaktight containers and vessels, electronic enclosures protecting from humidity, pipelines and pressure vessels, aerospace and automotive components, medical and pharmaceutical packaging, and underwater or submarine equipment.

Design considerations center on seals (gaskets, O-rings), welds, and seam integrity; surface finishes and mating components; materials compatibility with contained fluids; temperature and pressure ranges; assembly procedures; aging, fatigue, and damage can degrade leaktightness.

Testing and maintenance practices are standard in many industries; approved procedures are defined in international or national standards, depending on the application. When leaks are detected, repairs or redesign may be required to restore leaktightness.