A pipe provided to equalize the tank pressure with the atmospheric one while the tank is being emptied or filled. Air pipes terminating on the open deck shall be fitted with approved air pipe heads. However, air pipes from the fuel oil settling and service tanks should be led to the funnel in order to eliminate the risk of water ingress due to a broken pipe or head.
To meet requirements of the International Convention on Load Lines it is enough to arrange 760mm high air pipes on freeboard deck and 450mm height ones on forecastleand poop. However such standard approach is no more valid. Efficiency of many vessels depends on their damage stability characteristics: better damage stability allows higher permissible vertical centre of gravity. In order to improve damage stability of the vessel it is very important to arrange air pipes and vents as far as possible from ship sides and as high as reasonable.
