Rubber Gaskets vs. Graphite Gaskets: How to Choose?

In modern industrial production, sealing technology is one of the key factors to ensure equipment operates normally and production safety is maintained. Whether it is high-temperature, high-pressure pipelines in the chemical and petrochemical industries, or ambient-temperature, ambient-pressure equipment in the food and beverage industry, suitable sealing materials can effectively prevent medium leakage, extend equipment service life, and reduce maintenance costs. Among various sealing materials, rubber gaskets and graphite gaskets are undoubtedly the two most widely used. Each plays an important role in different industrial fields due to its unique performance and advantages. This article will explore in depth the performance characteristics, application areas, and differences between rubber gaskets and graphite gaskets, helping you make a wiser choice in practical applications.

Among various sealing materials, rubber gaskets stand out for their affordability and excellent performance, becoming the preferred choice in many industrial applications. Rubber gaskets are not only budget-friendly but also possess good sealing performance and wide applicability, capable of meeting sealing requirements under various working conditions.

Rubber gaskets are a widely used sealing material, commonly including flat rubber washers and rubber O-rings. They are usually made from natural rubber, nitrile rubber, neoprene, and other materials. After vulcanization, these rubber materials have good density, softness, and resilience, are easy to process into various shapes, and are relatively inexpensive and readily available on the market.

After vulcanization, rubber gaskets exhibit excellent compressibility and resilience, requiring only a low preloading force to achieve effective sealing under low-temperature and low-pressure conditions. This feature makes rubber gaskets very convenient to install and remove, and they can achieve good sealing even when the sealing surface is not perfectly flat.

Rubber has excellent extensibility and impermeability, effectively resisting the passage of gases and fluids, forming a very effective seal. This allows rubber gaskets to maintain good sealing performance in a variety of media.

Natural Rubber: After vulcanization, natural rubber has high elasticity and mechanical strength, good resistance to alkalis and weak acids, but poor oil resistance and low resistance to non-polar solvents, and is prone to aging under oxygen and ozone.

Nitrile Rubber (NBR): Exhibits excellent oil resistance, second only to polysulfide, polyacrylate, and fluororubber among common rubbers. It also has the mechanical strength and wear resistance required for sealing materials, widely used in dynamic and static seals. Its oil and low-temperature resistance are closely related to acrylonitrile content.

Neoprene (CR): A self-reinforcing elastomer with polarity second only to nitrile rubber, with physical and mechanical properties similar to natural rubber. It is more resistant to aging and chemical corrosion than natural rubber, has moderate oil resistance, resists inorganic acids and alkalis, and is flame-retardant.

EPDM Rubber: A copolymer of ethylene and propylene, with excellent ozone, aging, and weather resistance, outstanding electrical insulation and corona resistance, and excellent corrosion resistance in high-pressure steam. It also shows stability against polar chemicals, ethanol, ketones, esters, acids, bases, phosphate esters, and working oils, and is relatively inexpensive.

Silicone Rubber: Wide temperature range (-100℃~+350℃), excellent resistance to oxygen, ozone, light, and weather aging, good electrical insulation, high permeability, biocompatibility, and mold resistance. Specialty silicone rubber can also resist oil, radiation, and burning. Its disadvantages are low strength, poor acid and alkali resistance, and high cost.

Fluororubber (FKM): Excellent oil and high-temperature resistance, comparable to silicone rubber, highly resistant to corrosion, and stable against organic liquids (various oils, fuels, solvents, hydraulic fluids), high-concentration hydrogen peroxide, and other strong oxidizers. Domestic fluororubber is divided into Type 23 and Type 26. Type 23 has better resistance to strong oxidizing acids than Type 26, but Type 26 performs better against aromatic solvents, chlorinated organic solvents, fuel oil, hydraulic oil, lubricating fats, and boiling water.

Rubber gaskets have a wide range of applications, covering chemical, petrochemical, refining, chlorine-alkali, acid production, phosphate fertilizer, pharmaceutical, pesticide, synthetic fiber, dye and chemical, coking, gas, organic synthesis, food, beverage, and other production and processing sectors. They are commonly used in various mechanical equipment for cushioning, sealing, and buffering, suitable for water and non-mineral oil media under pressures below 6MPa and temperatures below 70℃.

If rubber gaskets shine for their affordability and versatility in ambient conditions, graphite gaskets display powerful sealing performance under extreme conditions such as high temperature, high pressure, and strong corrosion. Graphite gaskets, with their exceptional heat resistance, corrosion resistance, and stability in extreme environments, have become indispensable in many industrial sectors.

Graphite gaskets are sealing materials made by cutting or stamping pure graphite sheets or metal-reinforced graphite sheets. They are usually produced using specialized gasket cutting equipment. Reinforced graphite gaskets commonly use SS304, SS316, or tinplate as inner reinforcement, with thicknesses of 0.05–0.2mm. Forms include spiral-wound, mesh-reinforced, and flat reinforced composite gaskets. Edge-wrapped graphite gaskets often use 304 or 316L stainless steel as the covering material.

Outstanding High-Temperature and Corrosion Resistance: Graphite gaskets can operate stably in high-temperature, high-pressure, and highly corrosive environments for extended periods, ensuring equipment operates normally and reducing leakage risks. Flexible graphite maintains almost unchanged physical properties from -270℃ to 3650℃ (in non-oxidizing gases), and can be used in air up to about 450℃. It has excellent chemical corrosion resistance and resists almost all inorganic and organic media, except for strong oxidizers such as aqua regia, concentrated nitric acid, concentrated sulfuric acid, high-temperature dichromates, permanganates, and ferric chloride.

Good Compressibility, Resilience, and Plasticity: Graphite gaskets can adapt to different sealing surface shapes and sizes, achieving effective sealing even when flange surfaces are uneven. They require lower preloading forces than metal and spiral-wound gaskets, making them cost-effective and practical.

Self-Lubricating and Impermeable: Flexible graphite layers can slide under external forces, providing lubrication and reducing wear, with a low friction coefficient. It accommodates radial misalignment due to manufacturing or installation, and even if cracks appear, the gasket maintains close contact and prevents leaks.

Graphite gaskets are widely used in the chemical industry, mainly on pipeline flanges, heat exchangers, valve covers, and specially shaped flanges of liquid level meters and gauges. They are also used in refrigeration units, compressors, pumps, chemical instruments, and meters, replacing asbestos-rubber and metal-jacketed gaskets. They are suitable for sealing in pipelines, valves, pumps, pressure vessels, heat exchangers, condensers, generators, air compressors, exhaust systems, and refrigeration units. Graphite composite gaskets can be manufactured in unlimited large sizes, and special or non-standard products can be customized according to customer requirements.

Next, we provide a comprehensive comparison of rubber and graphite gaskets in terms of operating conditions, corrosion resistance, installation and maintenance, cost, and environmental impact.

Rubber Gaskets: Suitable for low-temperature, low-pressure conditions, with pressures below 6MPa and temperatures below 70℃, handling water and non-mineral oil non-corrosive media. They perform well in ambient-temperature, ambient-pressure equipment in chemical, petrochemical, food, and beverage industries.

Graphite Gaskets: Suitable for high-temperature, high-pressure, and corrosive environments, maintaining stable sealing under extreme conditions. They excel in chemical and petrochemical high-temperature, high-pressure pipelines, reactors, and heat exchangers.

Rubber Gaskets: Relatively weaker corrosion resistance; natural rubber and nitrile rubber are prone to aging and swelling in strong acids, bases, and organic solvents. Specialty rubbers such as fluororubber and silicone show significant improvements but are more expensive.

Graphite Gaskets: Excellent corrosion resistance, resisting almost all inorganic and organic media; only extremely oxidizing media cause corrosion.

Rubber Gaskets: Easy to install and remove; effective even on uneven surfaces. However, they degrade under high temperature and pressure, requiring regular replacement.

Graphite Gaskets: Installation and removal are also convenient, especially edge-wrapped types, which are easy to handle and resistant to damage. They remain stable under high-temperature and high-pressure conditions, with long service life and low maintenance costs.

Rubber Gaskets: Relatively inexpensive, especially natural rubber and nitrile rubber. Specialty rubbers are more costly.

Graphite Gaskets: Higher cost, especially reinforced or edge-wrapped types, but long service life and low maintenance offer high cost-effectiveness in the long term.

Rubber Gaskets: Some rubber production may generate environmental pollution, though eco-friendly rubbers are increasingly promoted.

Graphite Gaskets: Graphite is inherently environmentally friendly, with minimal impact during production.

Rubber and graphite gaskets each have advantages and disadvantages, suited to different operating conditions and applications. Rubber gaskets, with their affordability, ease of installation, and good sealing performance, perform well in low-temperature, low-pressure, and non-corrosive media environments. Graphite gaskets, with superior high-temperature, high-pressure, and corrosion resistance, dominate in high-temperature, high-pressure, and corrosive environments in chemical and petrochemical industries.

In practical applications, selection should consider equipment operating conditions, budget, and environmental requirements to ensure stable operation and production safety. Regardless of the gasket chosen, proper installation and maintenance are crucial to ensuring sealing performance. This comparative analysis aims to help you better understand the characteristics of rubber and graphite gaskets and select the most suitable sealing material for your project.