Pressure test (tank)

A tank pressure test proves the tightness and strength of a ship’s tank boundaries, either as a hydrostatic test filling the tank with water to a head set by the class rules, often to the top of the air or overflow pipe, or as an air/leak test pressurizing the closed tank and checking welds with a soap solution or vacuum box. The classification society testing schedule assigns each tank a structural (water-head) test or a leak test by tank type and location. Witnessed at new construction and after major repair, it detects weeping welds, deformed plating, and leaking penetrations before the tank enters service. Air pressure is held low for safety; structural strength is proved with water.