Marine parts are made of steel plates of sufficient thickness. It is composed of inner cylinder, outer cylinder and stationary blade. Both ends of the inlet and outlet of the outer cylinder are provided with flanges to connect with the ventilation pipe. The inner and outer cylinders are connected by stationary blades, which also guide the wind. The marine propeller with low speed and large diameter has higher efficiency. The rotation speed on warships is generally 150 ~ 400 rpm, and that on merchant ships is 80 ~ 150 rpm. For this reason, except for electric propellers, gear reducers with large reduction ratio are generally used between steam turbines and propellers. High speed, heavy load and high precision gear reducers are the key parts of marine steam turbine units, which all adopt 2-stage or 3-stage reduction. Marine gasket is a kind of marine pipe fittings. Its function is to seal the pipes after they are connected.