Flange gaskets are critical sealing components in industrial piping systems, widely used in industries such as petroleum and natural gas, chemical processing, power generation, and shipbuilding. They are designed to prevent fluid or gas leaks and ensure system integrity under varying temperature and pressure conditions. These gaskets are installed between two flange faces, maintaining the reliability of the connection structure through effective sealing. Selecting the appropriate gasket type and material is crucial for ensuring the safety and efficiency of system operation, particularly under harsh operating conditions. This article focuses on the types of flange gaskets, material selection, and their application areas.
Spiral Wound Gaskets
Spiral wound gaskets are a widely used type of flange sealing element in industrial applications. Their structure consists of V-shaped or W-shaped metal strips alternately wound with non-metallic filler material, forming a spiral-shaped composite layer. This design combines the high strength and good toughness of metal materials with the soft sealing properties of non-metallic filler material, resulting in a high-performance semi-metallic gasket.
Types of Spiral Wound Gaskets
Style CG – Is comprised of a sealing element and outer metal ring. The outer ring assists in locating the gasket on the mating flange faces and prevents over compression of the sealing element ensuring optimum sealing performance. Style CG gaskets are suitable for use on raised and flat faced flanged connections.
Style CGI – In addition to an outer metal ring the CGI style gasket is fitted with an inner metal ring, constraining the sealing element on both internal and external diameters. The inner ring functions as an additional compression stop and prevents inner buckling of the sealing element.Style CGI gaskets are suitable for use on raised and flat faced flanged connections and moderate to severe service conditions.
Style R – Is comprised of a sealing element, additional plies of metal are used at the start and termination of the winding process improving stability and sealing performance. Unlike other styles of spiral wound gasket compression of the sealing element is controlled by the use of the correct flange face configuration, style R gaskets are suitable for use on tongue and groove, male and female and flat to groove flanged connections.
Style RIR – Is comprised of a sealing element and inner metal ring. The inner ring functions as both a compression stop and creates a physical barrier between the sealing element and media stream. The inner ring is also designed to reduce turbulent flow, minimising flange erosion and prevents the build up debris in the annular space between the pipe bore and internal diameter of the gasket. Style RIR gaskets are suitable for use on male and female (spigot and recess) flanged connections.
Spiral Wound Gasket Color Codes
Flexitallic color coding meets the industry standard for metal and filler materials listed in ASME B16.20.
Application Areas
✅High-temperature steam, exhaust systems
✅Heat exchangers, chemical processing
✅Corrosive chemical environments
Metal Ring Joint Gaskets
Metal Ring Joint Gaskets (RTJ gaskets) are solid metal gaskets designed for high-pressure and high-temperature applications. They are commonly used in the oil and gas industry, particularly in offshore, refinery, and pipeline applications. These gaskets seal by plastic deformation when compressed between the groove of ring joint flanges, creating a very tight, metal-to-metal seal.
Octagonal vs. Oval Ring Designs
The oval ring joint gasket is designed with a smooth, rounded profile that fits precisely into the flange groove. When compressed, it creates a dependable metal-to-metal seal. Although widely used in traditional flange systems, it requires a fine surface finish and higher bolt load to ensure tight sealing.
The octagonal ring joint gasket features an eight-sided profile that delivers stronger sealing performance than the oval type. Its flat contact areas allow higher seating stress, making it suitable for demanding conditions such as high pressure and elevated temperatures. This shape is now the preferred choice in most modern flange applications.
Material Selection
•Carbon Steel: Suitable for many applications with temperatures up to 500°C.
•Stainless Steel (304, 304L, 316, 316L): Offers excellent corrosion resistance for chemical and marine environments.
•Special Alloys: Including 321 (0Cr18Ni10Ti) and 347 (0Cr18Ni11Nb) for high-temperature applications with improved resistance to sensitization and intergranular corrosion.
Application Areas
✅Flange connections
✅Pipe connections
✅Heat exchangers, valves, pumps, compressors
✅boilers and other types of industrial equipment
Metal Jacketed Gaskets
Among the various types of flange gaskets, metal jacketed gaskets stand out as a fundamental semi-metallic option. They combine the high-pressure suitability and blow-out resistance of metallic materials with the enhanced compressibility of soft non-metallic fillers. This design makes them an economical choice for applications with narrow sealing faces, such as heat exchangers. Available in diverse shapes and configurations, they offer adaptability across industries while maintaining reliability under demanding conditions.
Types of Metal Jacketed Gaskets
•Double Jacketed Gasket:Constructed of soft filler encapsulated by a metal jacket and insert. Designed for use on high temperature and pressure applications.
•Single Jacketed Gasket Constructed of soft filler covered by a metal jacket on both sides and one face. The gasket is ideal for narrow applications or moderate service conditions.
•Single Jacketed Gasket Totally Enclosed Constructed of soft filler completely enclosed in a single jacket for use in applications where the width does not permit the use of a double jacketed gasket.
•Single Jacketed Gasket Open on Outer Diameter Ideal for narrow applications where protection of the soft filler on the inner diameter is a requirement. Used in valve bonnets, sight glasses and vacuum Seals.
•Double Jacketed Corrugated (Soft Filler) The reduced contact area of the construction enhances compressive characteristics making it more suited to applications of lower bolt load or where flanges are uneven.
Material Selection
•Graphite + stainless steel shell: High temperature and corrosion resistant, suitable for petrochemical and high temperature pipelines.
•Ceramic fiber + carbon steel shell: Extremely high temperature resistant, suitable for boilers and heat treatment equipment.
•Mica + stainless steel shell: Insulating and heat resistant, commonly used in the electric power and metallurgical industries.
•Graphite + nickel-based alloy shell: Resistant to strong corrosion and high temperatures, suitable for chemical engineering and marine engineering.
Application Areas
Heat exchangers
Exhaust gases
Valve bonnet gaskets
Narrow flanges
Conclusion
There are many types of flange gaskets, and flange gaskets are an indispensable part of pipelines and industrial systems. Selecting the right type of flange gasket is crucial. By understanding the materials, application areas, advantages, and limitations of each type of gasket, you can make informed decisions to optimize system performance while ensuring safety and reliability.
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