Air Vents Heads

Marine air vents are used in vent piping for tanks, auxiliary spaces, and onboard piping systems where controlled communication with the atmosphere is required. Their function is to equalize pressure during filling, emptying, or thermal expansion of the contained medium, and to reduce trapped air at points where flow continuity, draining, or pump operation may otherwise be affected.

This category includes a cast iron marine air vent to JIS 5K, with flanged connection and straight-through flow arrangement. Selection should be correlated with the flange standard of the connected line, the nominal pressure class 5K, the vent line diameter, the installation location on deck or within an auxiliary space, and the degree of exposure to the marine environment.

Cast iron is used in general-service marine applications, provided that corrosion protection, coating system, gasket materials, and adjacent piping materials are compatible with the installation point. In lines exposed to seawater, humidity, or salt-laden atmosphere, the condition of the flange faces, bolting, seating surfaces, and any internal closing mechanism should be checked periodically.

During selection and maintenance, the effective vent area, pressure drop, risk of water ingress, accessibility for inspection and cleaning, accumulation of salt deposits or contaminants, and compliance with vessel class requirements should all be evaluated. The air vent should not be treated as a simple pipe termination, but as a functional component for tank protection and correct breathing of the piping system.