In the world of manufacturing and industrial maintenance, ensuring a leak-proof seal in flange connections is a constant priority. Historically, traditional pre-cut gaskets have been the go-to solution. However, with the advent of advanced adhesive technologies like anaerobic sealants, a crucial question arises: Can anaerobic sealants be used with a gasket, or should they replace them entirely?

At Incure, we understand that making the right material choice impacts everything from assembly efficiency to long-term operational reliability. Our goal is to provide clarity on these critical decisions, ensuring that professionals like you can optimize your projects with confidence.

The Core Principle of Anaerobic Sealants

To answer this question effectively, it’s essential to revisit how anaerobic sealants work. As we’ve explored in previous discussions, these unique adhesives cure in two specific conditions:

1. Absence of air (oxygen): They need to be confined between mating surfaces.
2. Contact with active metal surfaces: Metal ions act as a catalyst for the curing reaction.

This fundamental curing mechanism is key to understanding their compatibility with traditional gaskets.

Anaerobic Sealants and Traditional Gaskets: A Critical Distinction

Generally, anaerobic sealants are NOT designed to be used in conjunction with traditional, pre-cut gaskets (e.g., cork, paper, rubber, or even most semi-metallic gaskets). Attempting to combine them can actually lead to a compromised seal and potential failure. Here’s why:

• Oxygen Exclusion Interference: A traditional gasket, especially one made of fibrous or porous material, can trap air within the joint. This trapped oxygen prevents the anaerobic sealant from fully curing, leaving it as a liquid or a partially cured gel that offers little sealing integrity.
• Lack of Metal-to-Metal Contact: The gasket itself acts as a barrier, preventing the anaerobic sealant from making the necessary direct contact with the metal flange surfaces. Without this metal contact, the catalytic reaction needed for curing either won’t initiate or will be severely inhibited.
• Gap Management: Anaerobic flange sealants are designed for very tight, rigid, machined metal-to-metal joints, typically filling microscopic imperfections and gaps up to around 0.5 mm (0.020 inches). Traditional gaskets, by their nature, create a larger, more compressible gap. Anaerobic sealants are not formulated to effectively fill these larger, non-uniform gaps, again hindering proper cure and performance.
• Material Incompatibility: Some traditional gasket materials (e.g., certain rubbers or plastics) might not be chemically compatible with anaerobic formulations, potentially leading to degradation of either the gasket or the sealant.

The “Old Rule” to Remember: If you are using an anaerobic liquid gasket (also known as a “formed-in-place” or “FIP” gasket), you are typically replacing the traditional pre-cut gasket, not supplementing it.

When Anaerobic Sealants Are the Solution (Replacing Gaskets)

Anaerobic flange sealants are specifically engineered to replace traditional cut gaskets in applications involving rigid metal flanges. They offer significant advantages in these scenarios:

• Superior Leak Prevention: By completely filling all microscopic voids and imperfections between machined metal surfaces, they create a perfect, 100% surface-to-surface seal that is far more resistant to leaks than many traditional gaskets.
• No Relaxation or Creep: Unlike compressible gaskets that can relax over time, leading to loss of bolt load and leaks, cured anaerobic sealants form a tough, thermoset plastic that maintains its integrity and clamping force.
• Enhanced Assembly Integrity: They unitize the assembly, increasing its resistance to vibration and shock, which can cause traditional gaskets to fail and fasteners to loosen.
• Corrosion Protection: By sealing out moisture and preventing metal-to-metal contact, they inhibit fretting and galvanic corrosion.
• Simplified Inventory: A single tube can replace numerous sizes and shapes of pre-cut gaskets, reducing storage needs and complexity.

Examples of ideal applications for anaerobic flange sealants as gasket replacements:

• Gearbox housings
• Engine sumps (oil pans, unless a larger, flexible gap is present requiring RTV)
• Pump housings
• Compressor casings
• Rigid hydraulic and pneumatic connections

When Traditional Gaskets (or other sealants) Remain Relevant

While anaerobic sealants are highly effective in their niche, there are situations where traditional gaskets or other sealant types are still the appropriate choice:

• Flexible or Stamped Flanges: If the flanges are not perfectly rigid, or if they are made from stamped sheet metal rather than machined castings, their surfaces may be uneven or prone to movement. Anaerobic sealants require very tight, rigid contact to cure properly and may not perform well on these types of surfaces.
• Large Gaps: As mentioned, anaerobics are for small, controlled gaps. For larger or irregular gaps, RTV (Room Temperature Vulcanizing) silicone sealants are typically more suitable. RTVs are flexible and can fill larger voids while curing via atmospheric moisture.
• Dissimilar Materials: If one or both of the mating surfaces are non-metal (e.g., plastic to metal), an anaerobic sealant will not cure effectively. RTV silicones or other types of adhesives might be required.
• Required Disassembly Frequency: While many anaerobic flange sealants allow for disassembly with standard tools, some high-strength formulations can make disassembly challenging. For applications requiring very frequent, easy disassembly, a softer, reusable gasket or a specific non-hardening paste sealant might be preferred.
• Specific OEM Specifications: Always refer to the equipment manufacturer’s guidelines. Some OEMs specifically recommend or mandate the use of traditional gaskets or particular RTV formulations for warranty or performance reasons.

How Incure Guides Your Sealing Decisions

At Incure, we are committed to providing comprehensive solutions and expert advice to the manufacturing and industrial sectors. We help professionals like you optimize your projects by:

• Offering a Tailored Anaerobic Product Line: Our range of anaerobic flange sealants is designed to meet various performance needs, from instant sealing capabilities to high chemical resistance, specifically for replacing traditional gaskets on rigid metal-to-metal assemblies.
• Providing Unbiased Technical Consultation: We don’t just sell products; we offer insights. Our team can help you assess your specific flange application, material types, operating conditions, and gap sizes to determine whether an anaerobic sealant is the optimal solution or if an alternative technology is more appropriate.
• Ensuring Application Best Practices: We provide guidance on proper surface preparation, application techniques, and curing considerations to ensure that whichever sealing method you choose, it performs to its maximum potential.
• Supporting Innovation: For challenging or unique sealing requirements, we can explore custom adhesive formulations to develop a solution perfectly suited to your project.

Making the Right Sealant Choice

The question of using anaerobic sealant with a gasket isn’t about combining forces, but rather choosing the right tool for the job. For precise, rigid metal-to-metal flanges where you seek superior leak prevention, enhanced structural integrity, and simplified assembly, anaerobic flange sealants are designed to be your primary gasketing solution, replacing the need for traditional solid gaskets.

Contact Incure today to discuss your specific sealing challenges. Let our expertise help you implement the most effective and reliable sealing strategy for your industrial applications.