A Guide to O-Ring Material Selection

O-rings play a vital role in sealing fasteners. Sealing fasteners are hardware devices (e.g., sealing bolts, sealing screws, and sealing nuts) used to mechanically join two or more components together. They also form seals at the fastening point that prevent unwanted ingress or egress of materials. They have built-in O-rings, which create a tight hermetic seal once the fastening element is fully installed. 

The O-ring element in a sealing fastener can be made from a variety of materials depending on the intended application. It is important to choose the O-ring material carefully since the wrong material can result in the formation of an insufficient seal. This can negatively affect the integrity of process materials and/or the performance of equipment. 

The following article serves as a guide to O-ring material selection. It covers what to consider when vetting your options, what material options are available, and what benefits a properly designed sealing fastener may offer. 

Key Selection Considerations for O-Ring Materials

Elastomers are available in many formulations, each of which exhibits unique characteristics that make it suitable for particular applications. Knowing the differences between each elastomer is key to identifying the one that is best suited for your sealing fasteners’ O-rings. Some of the considerations to keep in mind when vetting the material options available include: 

• Where and how will the sealing fastener be used? 
• What types of contaminants may be present in the application environment? 
• What temperature conditions will the sealing fastener encounter? 
• Does the application involve normal or demanding conditions (e.g., coarse surfaces, repeated actuation, sharp objects)?
• How small or large is the budget compared to the cost of failure?

Types of O-Ring Materials

O-rings can be formed from a broad selection of materials to suit different environments and applications. Some of the most commonly used materials are: 

• Fluorosilicone. This material can withstand exposure to chemicals, ozone, petroleum, and soap, which is why it is often used in applications where exposure to fuel and oil is likely. It is also suitable for use in extreme temperatures, so it can be used in many geographic locations. 

• Silicone. This material is highly resistant to damage and degradation caused by dust, ozone, salt spray, soap, weather, and other harsh conditions and compounds. As such, it is widely used for outdoor applications. However, it is also utilized for various other industrial processes and environments. 

• Neoprene. This material offers relatively low compression set requirements. Additionally, it is used in a variety of industries for its resilience and toughness. 

• Buna-N. This material exhibits high strength, low compression set, and excellent resistance to abrasion and petroleum. For these reasons, it finds application in a range of industries, from automotive to oil drilling. 

Applications and Benefits of O-Rings and Sealing Fasteners

O-rings are essential components of many industrial and commercial applications. As part of sealing fasteners, they help keep critical process materials in and potential contaminants out. Typical industries that use them include: 

• Aerospace
• Agriculture
• Construction
• Defense
• Electronics
• Food & Beverage
• Industrial
• Infrastructure
• Lighting
• Marine
• Medical 
• Power Generation

Sealing fasteners that are properly engineered, selected, and installed can offer a number of advantages over traditional fastening and sealing solutions, such as: 

• Better corrosion resistance. Sealing fasteners are generally made from corrosion-resistant materials, such as stainless steel or zinc-coated steel. 

• Greater durability. The elastomeric materials used for the sealing elements will not break down when exposed to demanding conditions over time, so the fasteners can be used in harsh environments without losing integrity or becoming brittle. 

• Broader versatility. Sealing fasteners offer protection against moisture and many other contaminants, making them suitable for a range of sealing applications across the industrial, commercial, and consumer sectors.

• Easier installation. The installation requirements for sealing fasteners are much less complex and intense than traditional fastening and sealing solutions.  

• Lower cost of ownership. Sealing fasteners can be removed and reused, which makes them perfect for temporary fastening applications. However, they also offer excellent long-term performance in permanent fastening applications, which reduces maintenance and replacement costs. 

One type of sealing fasteners is sealing screws—also known as self-sealing O-ring screws. Compared to standard screws, APM Hexseal sealing screws have the following advantages: 

• They require a total compression of less than 20% of their original size when torqued. 
• They are available with anti-vibration and anti-movement features that lock them in place even when exposed to high noise and vibration levels, which protects the O-ring from damage caused by wear and tear. 
• They come pre-assembled, so they are ready to install out of the package.

Quality Sealing Solutions From APM Hexseal

If you need further assistance choosing a material for your sealing fastener O-rings, APM Hexseal is here to help. Equipped with over 70 years of experience milling, mixing, and molding sealing products, our team can identify the right material for any sealing application. Ask the experts today to get started. 

Ever Better.