Discharge Valves

A discharge or overboard valve is the hull fitting through which a vessel discharges drainage, sanitary or bilge water to the sea. It sits at the ship side and is one of the few valves whose failure floods the vessel rather than merely interrupting a process, so the body material, the closure integrity and the ease of operating it from an accessible position all matter more than they would inboard.

The straight form is used where the discharge line runs directly to the shell plating. Bodies here combine cast iron, ductile iron and cast steel, with the material and any coating selected for standing contact with seawater on the outboard side. Sizes cover a wide range, from small drain connections up to around DN300 at PN16.

When specifying, confirm the bore, the pressure rating, the medium, the hull arrangement and any classification society requirement, since overboard fittings are usually subject to survey. State the requirement on an enquiry and we can propose a configuration and the supporting documentation.