The hatch cover is the closing device of the cargo tank on the deck.It has the functions of sealing the hatch, protecting the goods from the wave,wind & rain, salt, supporting the platform.The main material is steel, sometimes aluminum and stainless steel are used.Main parts of hatch cover: Cover, Coaming, Rubber Sealing, Opening & Closing Device.The hatch cover has to be done the weathertight or watertight test according to the working conditions.