How Many Main Categories Are Gaskets Divided Into
author: www.qishine.com
2026-03-11
What is a Gasket?
A gasket is a fundamental component of static sealing. It is compressed between two flanges or connecting parts, utilizing its own elastic deformation to fill the microscopic irregularities of the flange sealing surfaces, thereby preventing the leakage of fluids (liquids or gases).
A gasket is a fundamental component of static sealing. It is compressed between two flanges or connecting parts, utilizing its own elastic deformation to fill the microscopic irregularities of the flange sealing surfaces, thereby preventing the leakage of fluids (liquids or gases).
In industries such as petroleum, chemical, power generation, marine, and machinery manufacturing, the performance of a gasket directly impacts the safe operation of equipment and environmental protection. Based on their material composition and structural characteristics, gaskets are typically divided into three main categories: Non-Metallic Gaskets, Semi-Metallic Gaskets, and Metallic Gaskets.
II. The Three Main Categories of Gaskets
1. Non-Metallic Gaskets
Non-metallic gaskets are usually soft, possess good compressibility and conformability, making them suitable for low-pressure, medium-temperature, or corrosive environments. They are often used as full-face gaskets or on raised face flanges.
1. Non-Metallic Gaskets
Non-metallic gaskets are usually soft, possess good compressibility and conformability, making them suitable for low-pressure, medium-temperature, or corrosive environments. They are often used as full-face gaskets or on raised face flanges.
Non-Metallic Gaskets: Rubber gasket, klinger c4430 gasket, klinger C4400 gasket, PTFE gasket, Gylon 3500 gasket
Rubber Gaskets
Made by cutting from rubber sheets or molding. Common materials include Nitrile (NBR, oil-resistant), EPDM (weather/acid/alkali resistant), Fluoroelastomer (FKM, high-temperature/strong chemical resistant), and Silicone.
Applications: Widely used for water, oils, mild acids, and alkalis. Commonly found in water piping, hydraulic systems, and low-pressure chemical pipelines.
Made by cutting from rubber sheets or molding. Common materials include Nitrile (NBR, oil-resistant), EPDM (weather/acid/alkali resistant), Fluoroelastomer (FKM, high-temperature/strong chemical resistant), and Silicone.
Applications: Widely used for water, oils, mild acids, and alkalis. Commonly found in water piping, hydraulic systems, and low-pressure chemical pipelines.
Non-Asbestos Gaskets
With increasing environmental requirements, asbestos gaskets are being phased out. Non-asbestos gaskets are made from materials like aramid fiber, carbon fiber, and rubber binders compressed together. Brands like Klingersil C4430, C4400 are internationally known non-asbestos sheets with excellent mechanical strength and high-temperature resistance.
With increasing environmental requirements, asbestos gaskets are being phased out. Non-asbestos gaskets are made from materials like aramid fiber, carbon fiber, and rubber binders compressed together. Brands like Klingersil C4430, C4400 are internationally known non-asbestos sheets with excellent mechanical strength and high-temperature resistance.
Applications: Suitable for oils, hydrocarbons, medium-strength acids/bases, and saturated steam. Widely used in petrochemical, marine, and power plant piping flanges, valves, and pump covers.
PTFE Gaskets (Polytetrafluoroethylene)
Possesses excellent chemical resistance, being virtually unaffected by most strong acids and bases. It also has a low friction coefficient and is non-stick.
Applications: Widely used in environments with highly corrosive media, such as sulfuric acid and hydrochloric acid transfer lines, as well as in food and pharmaceutical industries requiring clean conditions.
Possesses excellent chemical resistance, being virtually unaffected by most strong acids and bases. It also has a low friction coefficient and is non-stick.
Applications: Widely used in environments with highly corrosive media, such as sulfuric acid and hydrochloric acid transfer lines, as well as in food and pharmaceutical industries requiring clean conditions.
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Website: www.qishine.com
Email: qishine@qishine.com
Tel: 0592-5225595
WhatsApp: +86 15960259563
+86 15985833169
Modified PTFE Gaskets
To address the drawbacks of pure PTFE, such as cold flow and creep relaxation, modification is done through fillers or special processes. Materials like Gylon 3500 are modified to maintain corrosion resistance while significantly improving creep resistance and recovery rates, and reducing permeability.
To address the drawbacks of pure PTFE, such as cold flow and creep relaxation, modification is done through fillers or special processes. Materials like Gylon 3500 are modified to maintain corrosion resistance while significantly improving creep resistance and recovery rates, and reducing permeability.
Applications: Suitable for glass-lined equipment, piping, and corrosive media applications requiring high sealing loads. It solves the problem of traditional PTFE leaking easily due to pressure fluctuations.
2. Semi-Metallic Gaskets
Semi-metallic gaskets combine the strength of metal with the flexibility of non-metals. The metal provides structural support and resilience, while the non-metallic filler ensures sealing. These gaskets are suitable for high-temperature, high-pressure, or pressure-fluctuating conditions.
Semi-metallic gaskets combine the strength of metal with the flexibility of non-metals. The metal provides structural support and resilience, while the non-metallic filler ensures sealing. These gaskets are suitable for high-temperature, high-pressure, or pressure-fluctuating conditions.
Semi-Metallic Gasket: spiral wound gasket, kammprofile gasket, metal jackected gasket
Spiral Wound Gaskets
Made by alternately winding a V-shaped or W-shaped metal strip (typically stainless steel like 304, 316L) with a non-metallic filler strip (such as graphite, PTFE, non-asbestos paper).
Made by alternately winding a V-shaped or W-shaped metal strip (typically stainless steel like 304, 316L) with a non-metallic filler strip (such as graphite, PTFE, non-asbestos paper).
Depending on the flange face, they can have inner and outer rings (centering/strength rings).
Applications: One of the most common gaskets for high-temperature and high-pressure services. Widely used in heat exchangers, valves, and pipe flanges, especially in petrochemical refineries and main steam lines in thermal power plants.
Applications: One of the most common gaskets for high-temperature and high-pressure services. Widely used in heat exchangers, valves, and pipe flanges, especially in petrochemical refineries and main steam lines in thermal power plants.
Kammprofile / Grooved Gaskets
Features multiple concentric triangular grooves machined onto the sealing surfaces of a flat metal core. A layer of flexible material like graphite or PTFE is then bonded or applied to the grooved surfaces. This combines the high sealing stress of a serrated metal core with the conformability of a flexible facing material.
Features multiple concentric triangular grooves machined onto the sealing surfaces of a flat metal core. A layer of flexible material like graphite or PTFE is then bonded or applied to the grooved surfaces. This combines the high sealing stress of a serrated metal core with the conformability of a flexible facing material.
Applications: Suitable for high-pressure heat exchangers, high-pressure pipelines, and critical valves. Sealing performance is superior to plain metal gaskets, often requiring lower bolt preload.
Metal Jacketed Gaskets
Consists of a soft filler material (e.g., ceramic fiber, flexible graphite) encased in a metal jacket (e.g., copper, aluminum, stainless steel). They can be fully jacketed or have various jacket designs.
Consists of a soft filler material (e.g., ceramic fiber, flexible graphite) encased in a metal jacket (e.g., copper, aluminum, stainless steel). They can be fully jacketed or have various jacket designs.
Applications: Commonly used in large-diameter equipment flanges like heat exchangers and reactors. The filler provides resilience, while the metal jacket protects the filler from direct contact with the process fluid and erosion.
3. Metallic Gaskets
Metallic gaskets are made from a single metal and rely on the material's yield and plastic deformation to seal the flange faces. They withstand extreme temperatures and pressures but require high bolt preloads and demand high hardness and precision from the flanges.
Metallic gaskets are made from a single metal and rely on the material's yield and plastic deformation to seal the flange faces. They withstand extreme temperatures and pressures but require high bolt preloads and demand high hardness and precision from the flanges.
Metallic Gaskets: Corrugated gasket, serrated gasket, ring joint gasket
Corrugated Metal Gaskets
Features concentric corrugations formed on a flat metal core. The elastic deformation of these corrugations provides the sealing force.
Features concentric corrugations formed on a flat metal core. The elastic deformation of these corrugations provides the sealing force.
Applications: Suitable for situations with lower pressure but requiring some elastic compensation, such as vacuum systems or large-diameter low-pressure flanges.
Serrated Metal Gaskets
Has multiple concentric triangular serrations machined onto both surfaces of a flat metal core. Under bolt preload, the serration tips deform plastically, creating highly effective "line contact" seals.
Has multiple concentric triangular serrations machined onto both surfaces of a flat metal core. Under bolt preload, the serration tips deform plastically, creating highly effective "line contact" seals.
Applications: Commonly used in high-pressure, high-temperature applications like hydrocracking units and high-pressure steam lines. They typically require the use of high-temperature anti-seize compounds during installation.
Oval Ring / Octagonal Ring Gaskets (Ring Joint Gaskets)
Solid metal rings designed specifically for Ring-Type Joint (RTJ) flanges. Sealing is achieved through plastic deformation and elastic recovery when the ring is compressed into the groove of the flange.
Solid metal rings designed specifically for Ring-Type Joint (RTJ) flanges. Sealing is achieved through plastic deformation and elastic recovery when the ring is compressed into the groove of the flange.
Applications: Recognized as one of the gasket types with the best sealing performance. Suitable for extreme high-pressure (e.g., wellhead equipment) and high-temperature applications (e.g., high-pressure high-temperature steam).
Flat Metal Gaskets
The simplest type, cut from metal sheet. Materials can include soft iron, carbon steel, stainless steel, copper, aluminum, etc.
Applications: Used for rough flanges in low-pressure or specific applications, or as sealing gaskets in some heat exchangers.
III. Selection Summary
When selecting a gasket, the following factors typically need to be considered:
When selecting a gasket, the following factors typically need to be considered:
1. Medium Characteristics: Strong corrosives -> PTFE/Modified PTFE; Oils -> Non-asbestos or Spiral Wound; High-temperature oxidizing media -> Use graphite with caution.
2. Operating Temperature: Low temperatures -> Rubber or PTFE; Medium temperatures -> Non-asbestos or Spiral Wound; High temperatures (>500°C / >932°F) -> Must use Metallic gaskets (e.g., Serrated, Ring Joint) or special high-temperature graphite wound gaskets.
3. Operating Pressure: Low pressure -> Non-metallic; Medium to High pressure -> Spiral Wound, Kammprofile; Ultra-high pressure -> Metallic Ring Joint.
4. Flange Type and Facing:
Flat Face (FF): Non-metallic flat gaskets.
Raised Face (RF): Spiral Wound, Kammprofile gaskets.
Male-Female Face (MFM): Spiral Wound gaskets with inner rings.
Tongue & Groove Face (TG): Spiral Wound, Flat Metal, or Serrated Metal gaskets.
Ring-Type Joint (RJ): Must use Oval or Octagonal Ring gaskets.
Flat Face (FF): Non-metallic flat gaskets.
Raised Face (RF): Spiral Wound, Kammprofile gaskets.
Male-Female Face (MFM): Spiral Wound gaskets with inner rings.
Tongue & Groove Face (TG): Spiral Wound, Flat Metal, or Serrated Metal gaskets.
Ring-Type Joint (RJ): Must use Oval or Octagonal Ring gaskets.
In summary, understanding the classification and characteristics of gaskets is the first step towards achieving "zero leakage" operation in industrial piping and equipment. As modern industry trends towards higher temperatures, pressures, and corrosiveness, gasket technology continues to evolve, but the foundational framework of the "Three Main Categories" remains essential for understanding and applying gasket solutions.
Website: www.qishine.com
Email: qishine@qishine.com
Tel: 0592-5225595
WhatsApp: +86 15960259563
+86 15985833169
Email: qishine@qishine.com
Tel: 0592-5225595
WhatsApp: +86 15960259563
+86 15985833169
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