introduction

The appropriateness of the sealing ring, a vital sealing element, is essential to guaranteeing the system’s regular performance. However, a number of elements, including the working environment, media properties, and operational circumstances, must be taken into account while choosing a seal. In order to assist engineers and operators in making the right sealing ring selections to guarantee the dependability and safety of the system, this article will outline some important criteria and techniques for evaluating the appropriateness of sealing rings.

1. Understand the work environment:

1.1 Temperature range

Low temperature sealing ring: ideal for applications requiring sealing in colder climates (often operating between -100°C and -50°C). For these seals to keep their flexibility and sealing qualities, they must be well-suited to freezing temperatures. Rubber (VMQ) and fluoroelastomer (FKM) are two common materials used for low-temperature sealing rings.
Normal temperature sealing rings are appropriate for a variety of sealing needs in normal temperature settings, typically operating between -50°C and +120°C. In the typical temperature range, rubber sealing rings such nitrile rubber (NBR) and ethylene propylene rubber (EPDM) often function well as sealants.
High temperature sealing rings are appropriate for sealing applications in high-temperature settings, often operating in the +120°C to +400°C range or above. For high-temperature sealing rings to keep their suppleness and sealing effectiveness, they must be resistant to heat and oxidation. For high-temperature sealing rings, materials like polytetrafluoroethylene (PTFE) and polyimide (PI) are frequently utilized.
Extremely high temperature sealing ring: ideal for unique sealing needs in extremely high temperature settings (often operating at +400°C). Because of their strong heat and corrosion resistance, metal sealing rings made of copper or stainless steel are frequently employed in extremely hot environments.

1.2 Pressure conditions

Working pressure range: Materials and designs used to make seals should be able to resist the pressure range present in the working environment. A few bars to hundreds of bars or more are common operating pressures. The pressure resistance capacities of various sealing ring kinds and designs vary, thus it’s important to choose the right sealing ring based on the demands of the particular working environment.
Shocks and pressure fluctuations: Shocks and pressure fluctuations, such as hydraulic shocks in hydraulic systems, can happen in some working settings. Additional pressure stresses on the sealing rings may result from these pressure shocks and oscillations. This calls for the use of cushioning materials or shock absorbers in addition to other precautions such choosing a sealing ring with a better pressure resistance.
Static pressure and dynamic pressure: Under various pressure circumstances, the sealing ring is able to bear both static pressure and dynamic pressure, also known as moving pressure. When the sealing ring is moving, extra pressure is created by speed and inertia, referred to as dynamic pressure. Static pressure is the pressure applied to the sealing ring while it is at rest. Choose a seal material and design that can tolerate both pressure situations when making your seal selection.
Burst pressure: A sealing ring’s burst pressure is the pressure that surpasses its resistance to pressure and results in a rupture or leak. To guarantee the system’s dependability and safety, the sealing ring’s burst pressure needs to be significantly higher than the operating environment’s maximum pressure. As a result, you must make sure the sealing ring you choose has a pressure resistance significantly higher than the working environment’s maximum pressure.

1.3 Chemical media

Water: Used in many different applications, water is a typical chemical media. Water resistance is typically good for conventional rubber materials like ethylene propylene rubber (EPDM) and nitrile rubber (NBR).
Oils: Petroleum products and a variety of lubricants are popular chemical media. Nitrile rubber (NBR) and viton (FKM) are often resistant to common oil media.
Alkali and acids: Sealing ring materials are severely corroded by strong alkali and acid environments. Materials with excellent acid and alkali resistance include polytetrafluoroethylene (PTFE) and fluoroelastomer (FKM).
Solvents: Numerous applications call for the employment of a range of organic solvents and solvent combinations. Fluoroelastomer (FKM) and polytetrafluoroethylene (PTFE) often withstand common organic solvents with good resistance.
Steam: In the steam system, the sealing ring may be subjected to high-temperature and high-pressure steam medium. Sealing rings made of metal and those that include polytetrafluoroethylene (PTFE) are frequently utilized in steam conditions that are hot and pressurized.

2. Selection of sealing ring materials

NBR (NBR): NBR is a popular option for general liquid sealing applications. It works well with media like water, petroleum compounds, and certain solvents and has strong flexibility, wear resistance, and oil resistance.
Fluorine rubber (FKM): This material may be used in a variety of chemical media, oils, and high-temperature settings since it is resistant to high temperatures and chemical corrosion. It is resistant to oil, acids, and alkalis well.
Ethylene propylene rubber, or EPDM, is appropriate for hot water systems and a variety of outdoor applications due to its strong resistance to age and weather. It can withstand some acidic and alkaline conditions, steam, and water with good resistance.
Polytetrafluoroethylene (PTFE) is a highly chemically inert polymer that exhibits superior resistance to corrosion and elevated temperature stability. It works well in a variety of acidic and basic mediums, solvents, and hot conditions.
Styrene-butadiene rubber (BR): BR is appropriate for some low-pressure applications and dynamic sealing because it has strong wear and tear resilience.
Silicone rubber (VMQ): Suitable for high temperature conditions and applications in certain food and medical sectors, silicone rubber has good weather resistance and high temperature resistance.
Metal sealing ring: Metal sealing rings made of copper or stainless steel can offer good sealing performance and durability for sealing applications involving high temperatures, high pressures, or unique requirements.

3. Consider operating conditions

3.1 Friction and wear

When seals come into contact with comparably moving elements, friction happens. Heat produced by friction will wear down the sealing ring and the parts’ surfaces. It may also have an impact on the sealing ring’s flexibility and capacity to deform. Seals’ service life may be extended and friction and heat generation can be decreased with proper lubrication.
Wear: Usually brought on by friction, wear is the progressive loss or deterioration of material on a seal’s surface. Increased surface roughness, diminished sealing ability, and dimensional changes in the seal ring can all result from wear. Wear is influenced by a number of variables, including lubrication, friction, material hardness, and operating circumstances.
Lubrication: Sufficient lubrication prolongs the life and performance of seals while lowering friction and wear. Grease, lubricating oil, or the addition of lubricant can all be used to create lubrication. By minimizing direct contact between seals and components, lubricants can lower friction and heat production.
Surface treatment: The sealing ring and contact surface may undergo unique surface treatment for specific applications with unique needs. This may involve the use of low friction materials, hard coatings, or lubricating coatings. These surface treatments can lengthen the sealing ring’s life and increase its resistance to wear by reducing friction and wear.
Design optimization: To cut down on wear and friction, the sealing ring’s design can also be improved. Friction and wear issues can be improved, for instance, by lowering the contact pressure, minimizing the friction area, minimizing the radial force between the seal ring and the components, and improving the material choice of the seal ring.

3.2 Installation and disassembly

Install sealing ring:

Preparation: Make sure the work area is clean and clear of any debris or contaminants before applying the seal. Examine the sealing surface and ring for any damage or foreign objects.
Lubrication: Before fitting the sealing ring, if needed, add a suitable quantity of lubricant (such as oil or grease) to the contact surface and sealing ring. Lubricants lessen wear and friction.
Position of installation: Verify that the sealing ring is properly positioned on the sealing seat or sealing groove. Verify that the sealing surface and the lip of the sealing ring are correctly aligned.
Equal pressure: The sealing ring should be progressively pressed into the sealing groove or sealing seat during installation, with force applied equally throughout. To protect the sealing ring, keep sharp items and tools away from direct contact with it.
Inspection: Following installation, make sure the sealing ring fits evenly and firmly on the sealing groove or sealing seat and that it was placed correctly.

Remove the sealing ring:

Pressure Relief: In order to avoid an unintentional release or splashing, make sure to relieve or lower the pressure inside the system before removing the seal.
Using Tools: If required, assist in removing the seal by using a suitable instrument (such as a squeeze tool, digger, or removal tool). To protect the sealing groove and sealing seat, avoid piercing the sealing ring directly with sharp objects.
Light force disassembly: Using gentle pressure, extract the sealing ring bit by bit from the sealing seat or sealing groove. In order to prevent harming seals or other components, do not apply excessive force.
Inspection: After disassembly, examine the sealing ring’s state. A new sealing ring has to be installed if the existing one is badly worn out or broken.

3.3 Exercise requirements

Radial extrusion: Sealing is accomplished by radial extrusion, and the sealing ring is typically inserted into the seal groove or seal seat. In order to guarantee proper contact and a sealing effect between the sealing ring and the sealing surface, radial extrusion is the process of forcing the sealing ring up against the wall inside the sealing groove. In order to guarantee that the sealing ring fits snugly during operation and stop medium leakage, moderate radial extrusion can be used.
Radial deformation: When squeezed or released, seals, which typically possess some degree of elasticity, can flex radially. In order to maintain efficient sealing performance, radial deformation enables the sealing ring to adjust to various operating circumstances and pressure variations. The radial deformation capabilities of the seal should be considered in its design in order to meet the anticipated operational requirements.
Radial Sliding: When a seal comes into touch with comparatively moving pieces, it could be necessary for it to glide radially in some sealing applications. To lessen wear and friction and guarantee the longevity of sealing function, the sealing ring’s material choice and lubrication technique should account for this radial sliding.
Resilience: To maintain tight contact between the sealing ring and the sealing surface, the sealing ring has to have a specific amount of resilience and the ability to rapidly return to its original size and form after compression or release of pressure. Resilience has a key role in preserving sealing performance stability.

4. Experimentation and testing

Compression Test: A seal’s performance under compression is assessed through the use of compression testing. In order to replicate real-world working circumstances, this test usually entails inserting the seal into a compression device and exerting a certain amount of pressure. The performance and adaptability of the sealing ring may be assessed by measuring the dimensional changes, resilience, and sealing effect between the compressed sealing ring and the sealing surface.
Sealing performance test: This test assesses the sealing capacity of the sealing ring in a variety of operational scenarios. Both static and dynamic sealing performance measurements are included in this. Installing the seal in a test apparatus and seeing if it leaks at a specific pressure constitutes static testing. In dynamic testing, real-world operating circumstances are simulated for reciprocating, rotating, or oscillating motions, and the seal ring’s sealing ability is assessed.
Testing for durability: Under long-term usage and cyclic operating circumstances, durability testing is performed to assess the performance and life of seals. This comprises, among other things, testing for cyclic temperature, cyclic motion, and cyclic compression. It is possible to assess the durability and service life of the sealing ring by looking at how it performs and wears over time or after repeated cycles.
Testing the material: An essential first step in assessing the material performance and quality of sealing rings is material testing. This covers testing for things like chemical corrosion resistance, wear resistance, tensile strength, and material hardness. These tests may be used to assess the sealing ring material’s strength, flexibility, wear resistance, and chemical stability.
Test for compatibility: This test determines if the sealing ring and the working media are compatible. This covers, among other things, chemical resistance testing, media immersion testing, and media exposure testing. These tests establish the sealing ring material’s chemical stability and resistance to various media.

В заключение

It is important to take into account many considerations while choosing a seal, including the working environment, media properties, operational circumstances, and performance needs. To guarantee that the sealing ring can adapt to the particular working environment, choose the right materials and designs after thoroughly understanding the temperature range, pressure conditions, and chemical medium characteristics of the working environment. Furthermore, carrying out investigations and assessments as well as consulting with experts can offer a more thorough and trustworthy foundation for assessment. The efficiency, safety, and dependability of the system may be guaranteed by appropriately choosing and assessing the appropriateness of sealing rings.