1.Why are galvanized coils unsuitable for making high-quality rolled edge gaskets?
The mechanical properties of zinc coatings are poor.
**Too soft:** Pure zinc is relatively soft. During crimping and compression, the zinc layer is prone to excessive deformation, tearing, or peeling, rather than flowing uniformly and controllably like a specialized sealing material. This leads to discontinuous seals and creates leakage paths.
**Creep relaxation:** Zinc undergoes creep (slow plastic flow) under sustained pressure, causing the gasket's resilience to decrease over time. This can loosen flange connections and lead to leaks.
**Limited corrosion resistance:** The rust prevention principle of galvanized coatings is "sacrificial anode" protection, meaning zinc actively corrodes to protect the underlying steel substrate. In the service environment as a gasket, the zinc layer is gradually consumed.
Once the zinc layer is locally damaged (e.g., during cutting or crimping), the underlying steel substrate is exposed and forms a galvanic cell with the zinc, accelerating corrosion and quickly leading to rust penetration and leaks.
It cannot withstand many chemical media (such as strong acids and alkalis), limiting its application range.
2.In what situations might it be used?
Very low-pressure applications: For example, non-critical connections in air ducts and ventilation systems where sealing requirements are not stringent and the medium is dry air.
Temporary maintenance: As an emergency alternative when suitable materials are unavailable on-site.
Cost-sensitive, low-maintenance applications: In some non-critical, non-fluid sealing applications, such as simple dustproofing and partitions.
3.What metal materials are recommended for use as rolled edge seals?
Soft aluminum/pure aluminum coil: This is a very common material for rolled gaskets. It is soft, easily deformed, has good sealing properties, and is resistant to atmospheric corrosion. It is widely used in oil pans, valve covers, etc.
Copper coil: Also possesses good plasticity and conductivity, often used for high-temperature and high-pressure sealing (such as partial sealing of internal combustion engine cylinder head gaskets).
Low carbon steel coil (uncoated): For some non-corrosive environments, annealed low carbon steel can provide good strength and a certain degree of plasticity.
Stainless steel coil (e.g., 304, 316): Offers excellent corrosion resistance and strength, commonly used in the chemical, food, and pharmaceutical industries. To improve its sealing performance, it is sometimes coated with a soft coating (such as graphite-coated gaskets).
4.Why is it not recommended to use galvanized coils to manufacture rolled edge gaskets?
Its material properties do not match the characteristics required of a reliable gasket-such as uniform plasticity, creep resistance, good seal follow-through, and compatibility with the medium.
5.What factors should be considered when selecting a gasket material?
When selecting gasket materials, the working pressure, temperature, chemical properties of the medium, and required sealing level should always be taken into account. For metal crimped gaskets, soft aluminum and copper are far more reliable and professional choices than galvanized coils.