Ship doors can be classified according to their functions and usage characteristics into: watertight doors (watertight doors, weathertight doors, airtight doors, choke doors), fire doors, platform screen doors (copper valve doors, electromagnetic shielding doors, nuclear shielding doors), non watertight doors, and refrigerated doors.

Hot dip galvanizing has the advantages of uniform coating, strong adhesion, and long service life. There are various processes for cold galvanizing, also known as electroplating, for special doors and windows with quick opening and closing steel weathertight doors. Generally speaking, it involves cleaning, electroplating, and passivation processes. The color dullness refers to the color of the cold plated tube that we see, which belongs to zincate galvanizing. After passivation, the surface of the component is red, green, slightly yellow (Cr+6 red, Cr+3 green), and cannot appear purple (indicating loose passivation film layer). A simple method is to rub the surface of the component back and forth several times with your fingers, and there should be no color change (drop) phenomenon.

Hot dip galvanizing is the process of reacting molten metal with an iron substrate to produce an alloy layer, thereby bonding the substrate and coating together. Hot dip galvanizing is the process of first pickling steel components. In order to remove iron oxide from the surface of the steel, after pickling, it is cleaned in an ammonium chloride or zinc chloride aqueous solution or a mixed ammonium chloride and zinc chloride aqueous solution tank, and then sent to a hot-dip galvanizing tank.

In any process, the thickness of the coating also varies, and strict testing is still based on numbers. As the name suggests, a wind and rain tight door for ships is a type of door that prevents rainwater from entering and isolates wind and rain. Generally, wind and rain sealed doors for ships are divided into steel weight doors and aluminum doors.