Scelta degli anelli di backup: una guida

Summary

• Backup rings play a vital role in industrial sealing systems, supporting o-rings by preventing seal extrusion and deformation under high pressures.
• Understanding the function and importance of backup rings can greatly influence the efficiency and longevity of industrial applications across various industries.
• Selecting the right backup ring requires careful consideration of factors such as size, material, and application-specific conditions, ensuring optimal performance and durability.

Introduction

In industrial applications, even the smallest components often play critical roles in the efficient functioning of larger machinery and systems. Seals and rings, while seemingly minor, are integral elements that maintain proper performance by preventing leaks, ensuring pressure regulation, and upholding the system’s overall integrity.

One such critical component is the backup ring. Despite its modest size, the significance of backup rings within a sealing system is immense. These rings provide vital support to o-rings, effectively preventing seal extrusion and deformation under high pressures and extreme operating conditions.

This blog post aims to underscore the importance of backup rings in industrial applications by providing a comprehensive overview of their function, comparison to o-rings, historical development, applications across industries, and factors to consider when selecting backup rings. By sharing this knowledge, we aim to aid industry professionals and those interested in understanding the complexities of sealing systems in making informed decisions.

What are Backup Rings?

Backup rings are supportive elements used in sealing systems, typically with devices like o-rings. These rings fit in the groove or gland of a seal, where their distinct shape and rigidity prevent the o-ring from entering the clearance gap during high-pressure operations.

A backup ring is a robust, hardened ring that supports the o-ring, ensuring optimal functionality even under significant pressure or in extreme environments. The unique design of backup rings is pivotal to their effectiveness. Their rigid, circular shape ensures a perfect fit within the sealing assembly, while the material’s hardness prevents extrusion and deformation, ensuring the o-ring can maintain its necessary seal.

Backup rings can be either solid or split. Solid backup rings are single, continuous loops of material, ideal for static applications where the seal isn’t subject to dynamic motion. On the other hand, Split backup rings consist of a ring split at one point, allowing for easy installation in dynamic applications where the seal is subject to movement.

The choice of material for backup rings depends largely on the application. Common materials include Buna (Nitrile), Viton (FKM), HNBR, Teflon, Aflas, and more. Each material offers unique properties suitable for specific applications and environmental conditions.

Lastly, backup rings come in various sizes and standards, accommodating a vast range of applications. These standards can range from AS568 standard sizes to metric dimensions and even o-ring cord stock, allowing for tailored solutions that meet the exact requirements of different sealing systems. The adaptability of backup rings to various sizes and standards underlines their essential role in a multitude of sealing applications.

Comparison of Backup Rings to O-Rings

Backup rings and o-rings, though used together, are distinctly different in function. While o-rings primarily act as a seal to prevent the passage of liquids or gases, backup rings support these o-rings, particularly under high pressure or temperature. They are typically harder and have a lower coefficient of thermal expansion, preventing deformation or extrusion into the clearance gap.

However, it’s also essential to note the harmony in which these two components work. While the o-ring provides the initial seal, the backup ring reinforces its function, especially under harsh conditions. This synergy between the two components amplifies the overall effectiveness of the sealing system.

The History of Backup Rings

The evolution of the modern industry intrinsically ties to the history of backup rings. As technologies advanced and mechanical systems became increasingly complex and powerful, the need for more robust sealing solutions grew. The backup ring emerged as an essential player, providing critical support to o-rings in demanding applications.

• Early Industrial Revolution Era: Backup rings first emerged in the early 20th century in response to increasing pressures and temperatures in machinery during the Industrial Revolution.
• Material Evolution: Initially, backup rings were made from metal, but as the chemical industry progressed, superior polymers such as hard rubbers, nitrile, PTFE, and synthetic rubbers offered better performance.
• Design Evolution: The emergence of new materials facilitated the development of new backup ring designs, such as solid rings for static applications and split and spiral backup rings for dynamic applications.
• Standardization: Progression in industries led to the establishment of standards for backup rings, such as the AS568, to ensure consistency and reliability across applications.
• Space Missions: Backup rings found applications in NASA’s spacecraft and rovers, demonstrating their importance even in advanced technology.
• World’s Largest Backup Ring: The world’s largest backup ring, measuring 120 inches in diameter, is used in large-scale industrial applications, demonstrating the component’s versatility and adaptability.

This rich history, combined with the ongoing evolution and innovation of backup rings, underscores their importance in the contemporary industrial landscape. They have come a long way from their early days and are likely to continue evolving to meet the ever-progressing demands of industry and technology.

The Function of Backup Rings

Backup rings are crucial in high-pressure sealing systems, but their function extends beyond preventing o-ring extrusion. Their design aims to act as a ‘backup’ to the o-ring.

1. Extrusion Prevention: Backup rings prevent o-ring extrusion into the clearance gap during high-pressure operations.
2. Pressure Distribution: Backup rings help evenly distribute pressure, which is significant in systems experiencing pressure fluctuations or varying clearance gaps.
3. Friction Reduction: Backup rings reduce the effects of friction and wear on o-rings, minimizing abrasion.
4. Thermal Barrier: Backup rings act as a thermal barrier to protect o-rings from excessive heat, maintaining the seal’s structural integrity.

The Importance of Backup Rings

The importance of backup rings in an industrial setting extends beyond their ability to prevent extrusion in high-pressure environments. They serve as an integral part of ensuring system reliability and safety.

A lack of backup rings can lead to premature seal failure, system leaks, and even component damage, significantly disrupting operations and compromising system safety. Seal failure can have severe, potentially catastrophic consequences in critical applications, such as aerospace or power generation.

Financially, the implications can be considerable. The cost of system downtime, expensive repairs, and replacement parts can quickly add up. Moreover, the damage can extend to businesses’ reputations, particularly if system failures lead to safety incidents or compromise the quality of their products or services.

By increasing the lifespan of the o-rings, backup rings also contribute to sustainability efforts. Longer-lasting components mean fewer replacements, reducing waste and contributing to more efficient use of resources.

Backup Rings in Application

A variety of industries use backup rings due to their versatile nature. Industries like oil and gas, automotive, aerospace, heavy machinery, medical equipment manufacturing, power generation, and even the food and beverage sector heavily rely on them.

In the oil and gas industry, high-pressure environments are a common occurrence. Backup rings are frequently used in various equipment, such as drilling tools and valves, to withstand these harsh operating conditions. In the automotive sector, they’re used in hydraulic systems, fuel injectors, and brake systems to maintain optimal performance.

In the aerospace industry, where failure is not an option, backup rings are used in various applications like fuel systems, hydraulic systems, and engine components. They help ensure the reliability and safety of the components our modern aviation industry heavily relies on.

The medical equipment manufacturing industry also utilizes backup rings in various applications. For instance, in high-pressure sterilization equipment, backup rings ensure that the system remains sealed under high temperatures and pressures, contributing to the sterility and safety of medical devices.

In power generation, whether traditional forms like coal and gas or renewables such as wind and solar, backup rings are used in various components to ensure system efficiency and reliability. They help maintain seals in high-pressure steam systems, turbines, and more.

The food and beverage industry finds use for backup rings in processing equipment and packaging machinery. Their ability to withstand varying temperatures and pressures, coupled with their compatibility with food-grade materials, make them invaluable in maintaining system integrity and food safety.

The diverse applications of backup rings underscore their indispensability across various industrial contexts. 

How to Choose the Right Backup Rings

Selecting the right backup ring for your specific application can be critical to the success of your sealing system. It isn’t as simple as one size fits all; it requires understanding the application requirements and how each factor influences the choice of backup ring. Here are the key factors to consider:

• Pressure Consideration: High-pressure applications require backup rings made from harder materials for higher extrusion resistance.
• Temperature Influence: The choice of backup ring material can be affected by temperature as materials react differently to temperature changes. View our compounds page for a summary of ideal temperature ranges for each material.
• Chemical Compatibility: The choice of backup ring material should be resistant to the chemicals it will be exposed to in the application. Try our interactive chemical compatibility tool that rates our most common o-ring materials against chosen materials.
• Clearance Gap Size: The size of the clearance gap influences the backup ring’s size and type.
• Dynamic or Static Application: The type of movement in the application influences the choice of backup ring, with solid rings often used in static applications and split or spiral rings in dynamic applications.
• Material Hardness: The hardness of the backup ring material influences its ability to resist extrusion and deformation.
• Regulatory Requirements: Certain industries may have additional regulatory requirements for backup rings.

Remember, each application has unique requirements, which are crucial to selecting the appropriate backup ring. A careful and thoughtful selection process ensures that your sealing system delivers the performance, reliability, and longevity it aims for.

Conclusion

Backup rings may seem like small components in the grand scheme of industrial applications, but their role is vital. They prevent o-ring extrusion in high-pressure environments, increase the efficiency and lifespan of seals, and have broad applications across various industries. The right backup ring can improve your sealing system’s reliability, durability, and overall performance.

Here at Global O-Ring and Seal, we understand the importance of high-quality sealing solutions. We offer an extensive range of backup rings, o-rings, and related seals, providing you with the reliability and performance your applications demand. Explore our wide range of seals today and experience the difference that quality makes. To shop for backup rings, visit our online store.