In modern industrial production, the safe operation of equipment depends on high-performance sealing solutions. Gaskets, as indispensable sealing elements in flange connections and piping systems, directly affect equipment reliability and operational efficiency. Corrugated graphite gaskets, with their unique composite structure of a metal core and expanded graphite, have gradually become the preferred choice in various industrial sealing applications due to their excellent sealing ability, outstanding high-temperature performance, and wide applicability. This article will provide a comprehensive analysis of the structural principles, performance advantages, application areas, and selection and maintenance methods of corrugated graphite gaskets, offering reference for engineering design and equipment operation.
A corrugated graphite gasket is a high-performance sealing element composed of a metal core and expanded graphite material. The upper and lower surfaces of the metal core are machined with specially shaped concentric grooves that are offset from each other to form a unique corrugated structure. A layer of expanded graphite of appropriate thickness is then bonded onto the metal core to form the overall gasket. This special construction allows, during use, for the graphite material to be compressed into the grooves when the flange is tightened. The annular peaks of the metal core make tight contact with the flange surfaces and undergo elastic deformation under further tightening. The expanded graphite is highly compressed and enclosed in the annular space between the metal core and flange surfaces, achieving excellent sealing performance.
After understanding the structural principles of corrugated graphite gaskets, we must ask: what significant performance advantages does this unique design bring? Next, let us explore the performance advantages of corrugated graphite gaskets and their outstanding performance in the sealing field.
Corrugated graphite gaskets combine the dual effects of ridge-shaped metal sealing and expanded graphite material sealing. Their sealing bands are completely separate, unlike the helical bands of spiral-wound gaskets. This unique structure gives corrugated graphite gaskets exceptionally excellent sealing performance. In airtightness tests, under 35 MPa compression, the gasket can achieve extremely high sealing, with a leakage rate of 10^-5 cm³/s. Even under low-pressure conditions, such as 15 MPa, the airtightness can reach 10^-3 cm³/s, far higher than the 10^-2 cm³/s specified in asbestos rubber sheet standards. This outstanding sealing performance effectively prevents gas or liquid leakage, ensuring the safe operation of industrial equipment.
The metal core of the corrugated graphite gasket has a special structure similar to an elastic element, providing good elasticity to the entire gasket. During use, the elasticity of the metal core can effectively respond to pressure and temperature fluctuations, maintaining tight contact between the gasket and the flange surfaces. At the same time, because the elasticity mainly comes from the metal core, the expanded graphite material will not experience stress relaxation under long-term compression, allowing the gasket to maintain excellent sealing performance for a long time. This is crucial for industrial equipment that requires long-term stable operation, avoiding the risk of leakage due to gasket performance degradation.
Both the metal and expanded graphite materials of corrugated graphite gaskets possess excellent high-temperature resistance and fluid corrosion resistance. Expanded graphite remains stable under high-temperature conditions and does not age or lose sealing performance. The metal core is selected according to different operating environments, such as carbon steel or stainless steel, to meet the corrosion resistance requirements of various fluid media. This high-temperature and fluid corrosion resistance allows corrugated graphite gaskets to operate stably under harsh conditions, such as high-temperature, high-pressure, and corrosive fluid environments in the petrochemical industry, and high-temperature steam environments in the power industry.
During use, the annular peaks of the metal core make tight contact with the flange surfaces, and the expanded graphite material is enclosed by the sturdy metal core and flange surfaces. This structural design prevents the graphite material from being washed away by high-pressure fluids or collapsing like spiral-wound gaskets, ensuring gasket safety and reliability. Compared with metal gaskets, corrugated graphite gaskets are more convenient to install and use, and do not suffer from sealing failure due to improper installation. Additionally, the overall structure is not easily damaged during transport and installation, further improving safety.
Corrugated graphite gaskets can be used in almost all conditions, including high and low temperatures (-200°C to +700°C) and high and low pressures (vacuum to 25 MPa). Corrugated graphite gaskets made with appropriate metal core materials can be used in various applications, including most corrosive fluids. Whether in high-temperature, high-pressure steam pipelines, low-temperature liquefied gas storage tanks, or highly corrosive chemical media pipelines, corrugated graphite gaskets provide reliable sealing. The pure graphite non-metallic sealing layer in the dual-seal mechanism ensures excellent sealing even with minimal flange surface machining and can maintain high sealing performance under low compressive stress, making it particularly suitable for applications with strict sealing requirements, such as gas systems.
Corrugated graphite gaskets are an economical type of gasket. In industries such as petrochemical and power plants, for non-corrosive fluids like various oils and steam, carbon steel corrugated graphite gaskets can replace spiral-wound or ridge-shaped gaskets, saving significant costs. Furthermore, in general applications, corrugated graphite gaskets can be reused, further reducing usage costs. They are easy to install, ensuring installation quality and avoiding equipment damage and increased maintenance costs due to improper installation. In the long run, they offer high cost-effectiveness.
Since entering the market in the early 1990s, corrugated graphite gaskets have been widely applied in petroleum, chemical, power, textile, and other industries due to their excellent performance. Actual operating parameters range from low pressures to high pressures of 26 MPa, and temperatures from -96°C in air separation systems to 700°C in high-temperature cracking systems. Gasket sizes from DN10 piping flanges to DN2500 vessel flanges can all be perfectly matched.
In the petroleum industry, corrugated graphite gaskets are widely used in crude oil pipelines and refinery equipment flange connections, effectively preventing oil leaks and ensuring production safety. In the chemical industry, whether in reactors, heat exchangers, or storage and transport equipment for various chemical media, corrugated graphite gaskets provide reliable sealing solutions, ensuring smooth chemical production. In the power industry, they are used in steam pipelines, turbines, and boilers of power generation units, ensuring stable operation and improving power generation efficiency. In the textile industry, they are used in steam and hot water pipelines, meeting temperature and pressure requirements during production and ensuring product quality.
Corrugated graphite gaskets mainly have two types: those with positioning rings for flat flanges, and those without positioning rings for raised-face flanges. In practice, the appropriate type should be selected according to flange type and operating conditions. For different temperatures and media, different metal core materials and non-metallic materials should be selected. For example, in high-temperature environments, high-temperature resistant metal cores such as stainless steel can be chosen; for highly corrosive media, more corrosion-resistant metals such as nickel-based alloys should be selected. Meanwhile, the performance of the expanded graphite material should also be adjusted according to specific operating conditions to ensure optimal sealing performance during use.
Installation and Maintenance of Corrugated Graphite Gaskets
Proper installation and maintenance are key to ensuring the sealing performance of corrugated graphite gaskets. During installation, flange surfaces must be clean, flat, and free of debris or scratches. Place the gasket in the center of the flange, ensuring the positioning ring (if present) aligns with the flange holes. When tightening bolts, follow a symmetrical and uniform sequence, gradually increasing the torque to avoid uneven stress that could affect sealing. After installation, sealing performance should be checked using gas or liquid leak detection to ensure correct installation and good sealing.
During use, regularly inspect the gasket's sealing status for any signs of leakage. For long-term operating equipment, regular replacement is recommended to maintain reliable sealing performance. When replacing, thoroughly clean the flange surface and remove old gasket residues to ensure the new gasket adheres closely to the flange. Proper storage is also important to prevent moisture, heat, or mechanical damage, extending the gasket's service life.
In conclusion, corrugated graphite gaskets, with their unique structure, excellent sealing performance, and broad applicability, demonstrate irreplaceable value in the industrial sealing field. Whether in high-temperature, high-pressure petrochemical pipelines or low-temperature, low-pressure liquefied gas tanks, corrugated graphite gaskets ensure safe and stable operation. Through scientific selection, standardized installation, and regular maintenance, users can fully utilize their outstanding performance and achieve cost-effective, long-term application, ensuring the safety and reliability of industrial equipment.
