Hatch covers are the collective name for the lids on the ship that close various hatches and their opening and closing devices. The main function of the hatch cover is to ensure that waves and rain do not penetrate the cargo hold, and some hatch covers also bear the weight of the cargo on the deck.
According to the size of the hatch, it is divided into a large hatch and a small hatch. The former is used to hold bulk dry cargo, goods or vehicles, and is also called cargo hatch; the latter is used to hold cargo tanks, refrigerated cargo, etc., as well as personnel access hatches and manholes. According to the hatch cover material and type, there are a whole piece of wood or metal hatch cover, wooden assembled hatch cover, box or corrugated profile plate made of metal or glass fiber reinforced plastic, etc. Small hatch covers are generally opened and closed manually, and large hatch covers must be opened and closed by electric or hydraulically driven machinery. According to the transmission method, it can be divided into rolling hatch covers, rolling type includes vertical type, oblique type, sleeve type, rolling type includes side shift type, laminated type, rolling type, and hinge type includes hinge type, folding type, etc. According to the tightness, there are watertight, oiltight, airtight and non-tight hatch covers, etc. According to different tightness requirements, the hatch cover and the adjacent parts are equipped with beading, packing, gaskets, compactors, etc Composed of tank closures or seals.