Do Gaskets Need Sealant? Here’s What You Should Know
Many industrial applications raise the question of whether gaskets need sealant. The answer depends on the gasket type, the flange surface, and the conditions it will operate under. While some gaskets are designed to seal on their own, others may benefit from a sealant to improve performance or prevent leaks.
This article explains when sealant is recommended, when it should be avoided, and what to consider for materials like cork.
When Gaskets Need Sealant (and When They Don’t)
Most gaskets are manufactured to seal effectively without sealant. The gasket material, surface finish, and bolt load usually determine performance. But in some cases, adding a sealant can help.
Sealant may be helpful when:
- The flange surface is scratched, uneven, or pitted
- The bolt load is low or uneven
- The equipment is old or worn
- A temporary repair is needed
Sealant should be avoided when:
- The gasket is coated or pre-treated for dry installation
- The sealant may react with the process media
- The sealant can block flow paths or break down under pressure
- The equipment manufacturer recommends a dry install
Sealant use should be based on function, not habit. A well-installed gasket on clean, flat surfaces with correct tension rarely needs anything extra.
Do Cork Gaskets Need Sealant?
Cork gaskets are often used in applications with oils, fuels, or vibration. Their natural compressibility helps form a tight seal on uneven or flexible surfaces.
In most cases, cork gaskets can be installed dry. A clean, flat flange surface and even bolt load are usually enough to create a proper seal. But in some situations, a light coat of non-hardening sealant can help prevent leaks.
Sealant may help with cork gaskets when:
- The surface is damaged or irregular
- The gasket needs to stay in place during assembly
- Additional sealing is needed for low-pressure systems
Avoid using sealant that hardens or reacts with cork, as this can cause cracks or leaks. Always check compatibility with the fluids and temperature range in the application.
Types of Sealants Used with Gaskets
Not all sealants work the same. Choosing the right one depends on the gasket material, the media involved, and the temperature and pressure of the system.
Common sealant types include:
- RTV Silicone: Flexible and resistant to oil and temperature. Often used in engines and machinery.
- Anaerobic Sealants: Cure in the absence of air, ideal for metal-to-metal flanges with minimal gaps.
- Non-Hardening Paste Sealants: Stay pliable and allow easy disassembly. Useful in low-pressure or vibration-prone systems.
- Spray Adhesives: Used to hold gaskets in place during installation, not for sealing.
Each type has its place. Using the wrong sealant can damage the gasket or lead to failure. Always match the sealant to the application and material.
Risks of Using Sealant Incorrectly
Using the wrong sealant—or using it when it’s not needed—can cause more problems than it solves. While sealant may seem like added protection, it can interfere with gasket performance if misapplied.
Common risks include:
- Over-application: Excess sealant can squeeze out, block passages, or affect pressure flow.
- Material incompatibility: Some sealants break down rubber, cork, or other gasket materials.
- Reduced sealing performance: A hard or brittle sealant can prevent proper compression of the gasket.
- System contamination: Sealant debris can enter pipes, pumps, or filters and cause damage.
Always follow equipment specifications and avoid sealant unless there’s a clear benefit for the specific job.
Our Recommendation for Industrial Use
In most industrial settings, a gasket should be installed clean and dry unless the application calls for something different. The condition of the flange surface, the type of gasket material, and the system pressure all affect the need for sealant.
When in doubt:
- Check the equipment manufacturer’s guidelines
- Use sealant only if it improves sealing without compromising the gasket
- Choose a sealant that matches the temperature, media, and material
If sealant is used, apply a thin, even layer—only where it’s needed. Avoid overuse. The goal is to support the seal, not replace the gasket.
For more precise or critical applications, talk to an expert who understands how sealant will interact with your system.
Do You Really Need Sealant? Key Takeaways for Industrial Use
Gaskets are built to seal, and in most cases, they do not need sealant. When the right gasket is used with the right installation method, additional sealant is rarely required. But when surface quality or conditions aren’t ideal, sealant can help—if applied correctly.
Seal performance depends on more than just the material. It also depends on how it’s installed and where it’s used.
If you’re unsure whether to use sealant in your application, it’s best to get advice before installation. Our team at Queensland Gaskets can help you choose the right gasket and method for the job.
Need support with material selection or gasket performance?
Get in touch with Queensland Gaskets for expert guidance backed by decades of industrial experience.
FAQs
Should I use gasket sealant on both sides?
Only if the application requires it. In most cases, sealant on one side is enough. Applying it on both can affect compression and may cause leaks.
Can gasket sealant replace a gasket?
No. Sealant is not a substitute for a gasket. It may help improve a seal, but it cannot replicate the compression and material properties of a proper gasket.
Do rubber gaskets need sealant?
Rubber gaskets are usually installed dry. Sealant is rarely needed unless the surface is damaged or the system requires extra hold during assembly.
What happens if I don’t use sealant when required?
You may experience leaks, pressure loss, or premature gasket failure. Always assess the surface and application to determine if sealant is needed.
Is sealant safe for high-temperature applications?
Some sealants are rated for high heat, but not all. Always check the sealant’s temperature rating against your application before use.
