The selection of gasket materials for marine manhole covers is subject to very strict requirements to ensure their sealing performance and service life. The following are the main requirements for gasket material selection:
Corrosion Resistance:
The gasket material must be able to resist the erosion of seawater, salt spray, and other corrosive media to ensure that the gasket does not fail due to corrosion during long-term voyages.
Stainless steel (such as 304 stainless steel and 316L stainless steel) is a commonly used corrosion-resistant material. 316L stainless steel, due to the addition of molybdenum, has better resistance to organic acid corrosion.
Sealing Performance:
The gasket material should have good elasticity and plasticity to ensure a tight fit against the opening surface when the manhole cover is closed, forming an effective seal.
Asbestos rubber gaskets are a commonly used sealing material, offering good sealing performance and corrosion resistance at a moderate price.
High Temperature Resistance:
In certain special cases, such as high-temperature areas like ship engine rooms, the gasket material needs to withstand high temperatures without deformation or failure.
High-temperature resistant rubber or other special alloy materials may be used in these high-temperature environments.
Strength and Durability:
Gasket materials should possess sufficient strength and durability to withstand the weight of personnel, equipment, and goods, as well as the friction and impacts that may occur during use.
While carbon steel (cast iron) has high strength, it is prone to rusting and therefore typically requires anti-corrosion treatment, making it unsuitable for direct use as gasket material. However, carbon steel can be used to manufacture the main structure of manhole covers.
