Guidelines for Selecting Material Properties And Sealing Forms

Choosing the appropriate sealing form based on different materials is a complex decision-making process involving multiple factors.  Here are some basic principles and guidelines for selecting sealing forms based on material properties:

1、 Consider the fundamental properties of materials

①　High temperature resistance:

For seals that need to work in high-temperature environments, high-temperature resistant materials should be selected, such as metal O-ring seals (usually made of high-strength metal materials such as stainless steel, aluminum alloy, titanium alloy, etc.) or graphite sealing materials.

Although rubber sealing rings have good elasticity, their high temperature resistance is limited, and they are generally difficult to work stably in high temperature environments exceeding 250 ° C.

②　Pressure resistance and chemical corrosion resistance:

In high-pressure or highly corrosive media, metal seals (such as metal O-ring seals or metal to graphite seals) are usually more reliable than rubber seals.

Graphite sealing materials also have good chemical corrosion resistance and are suitable for sealing requirements in corrosive media.

③　Wear resistance:

Metal sealing rings have high mechanical strength and wear resistance, making them suitable for high friction or wear environments.

The wear resistance of rubber seals is relatively poor, but their sealing effect is usually better than that of metal seals in low-pressure, low-temperature, and general temperature environments.

2、 Consider the characteristics of the sealing form

①　Packing seal:

Suitable for sealing of medium and low pressure and rotating shafts.

It can be divided into soft packing seals (such as packing) and hard packing seals (such as split rings and split rings).

The selection of packing material should consider factors such as working medium temperature, pressure, acidity and alkalinity, as well as the surface roughness of mechanical equipment.

②　Mechanical seal:

Suitable for sealing high-pressure, high-temperature, high-speed, and corrosive media.

Composed of rotating and stationary components, it prevents fluid leakage by maintaining contact through relatively sliding end faces.

Metal to graphite seal is a common form of mechanical seal, which has excellent resistance to high temperature, high pressure, and corrosion.

③　Dry gas seal:

Belonging to non-contact sealing, it has good sealing performance, long service life, and does not require a sealing oil system.

Suitable for high-speed fluid machinery such as centrifugal compressors, as well as working conditions where a small amount of process gas leaks into the atmosphere without harm.

④　Maze seal:

Suitable for situations with small pressure differences.

By setting several sequentially arranged annular sealing teeth around the rotating shaft, a series of interception gaps and expansion cavities are formed to achieve the purpose of preventing leakage.

⑤　Oil seal sealing:

It is a self tightening lip seal with a simple structure, small size, and low cost.

It can prevent medium leakage and also prevent external dust and other harmful substances from entering.

But it is not resistant to high pressure and is generally used in chemical pumps for low-pressure applications.

⑥　O-ring seal:

It can be divided into metal O-ring seals and rubber O-ring seals.

Metal O-ring seals have excellent high temperature resistance, pressure resistance, and chemical corrosion resistance, but they are expensive and complex to process.

Rubber O-ring seals have good elasticity, a wide temperature range, and low cost, but may fail in high temperature and high pressure environments.

3、 Considering the application scenarios comprehensively

①　High temperature and high pressure environment:

In high-temperature environments such as furnaces and combustion chambers, metal O-ring seals or metal to graphite seals should be selected.

②　Flammable and explosive media:

Metal to graphite sealing is safer and more reliable due to the use of elastic deformation of the metal sealing surface and the graphite sealing surface to "press" together, making it suitable for sealing flammable and explosive media.

③　Corrosive media:

Graphite sealing material has good corrosion resistance and is suitable for sealing requirements of corrosive media.

④　Low pressure and low temperature environment:

The sealing effect of rubber O-ring seals is usually better than that of metal O-ring seals in low-pressure, low-temperature, and general temperature environments.

In summary, when choosing a sealing form, it is necessary to comprehensively consider the basic properties of the material, the characteristics of the sealing form, and the requirements of the application scenario.  By making reasonable choices, the reliability and durability of the seal can be ensured, and the efficiency and safety of mechanical equipment can be improved.