Horizontal pressure test

A horizontal pressure test is a tank tightness and strength test carried out with the ship or block in the horizontal building position, filling the compartment with water to a defined head, often to the top of the overflow or air pipe, to prove the boundary welds and detect leakage before the structure is closed out. It is one of the structural test cases in the classification society testing schedule for ballast, cargo, and fuel tanks. The required head and whether a tank gets a hydrostatic (water-head) test or an air/leak test depends on the tank type and class rules. Weeping welds, deformed plating, and leaking penetrations are marked and repaired before acceptance.