May 4, 2026
Gasket selection decisions are prone to error if not carefully evaluated. The diversity of materials, face configurations, pressure ratings, and service conditions is such that a gasket proven reliable in one application may fail rapidly in another. In process piping, small leaks are easy to overlook until they turn into bigger problems. It often begins with a minor leak, a stain on the insulation, or a joint that requires more frequent retorquing than expected. Left unaddressed, these issues can escalate into increased maintenance costs, extended downtime, and elevated safety risks.
Understanding the main types of gaskets in piping systems is the foundation of reliable, long-term sealing. The right flange gasket for a given service is determined by the operating temperature, pressure class, process chemistry, and joint behavior under thermal cycling. Making the right gasket selection decision from the start reduces leak risk, lowers maintenance burden, and protects both personnel and production continuity.
At a glance, here’s how the main gasket types compare in common piping applications.
| Gasket Type | Typical flange face | Recommended for | Limits |
|---|---|---|---|
| Full face gasket | Flat face flanges | Lower-pressure service, water, HVAC, utilities, and brittle flange materials | Not ideal where higher seating stress is needed |
| Ring-type gasket | Raised face flanges | Most industrial process piping, including higher-pressure service | Must be centered properly; not suitable for flat face flanges |
| Rubber flange gasket | Usually flat face or lower-load applications | Moderate temperature and pressure services where conformability matters | Not suitable for high temperatures or aggressive chemicals |
| Compressed non-asbestos sheet gasket | Flat face or raised face, depending on the cut | General industrial service across a range of temperatures and pressures | Must be matched carefully to service conditions and gasket geometry |
Below, we take a closer look at the most common gasket types used in industrial piping, where each one belongs, and what factors should drive material selection.
Everything You Need to Know About Flange Gaskets
A flange gasket is the sealing element placed between two mating flange faces in a bolted joint. When the bolts are tightened, they compress the gasket against both flange surfaces, creating a barrier that prevents fluid or gas from migrating out of the system. The integrity of that barrier depends on three things working together: adequate bolt load, appropriate gasket material for the service conditions, and flange faces that are in acceptable condition.
Flange gaskets are the most common type of gasket found in industrial piping. They appear at virtually every connection point in a process plant: pipe-to-pipe joints, valves, heat exchangers, pumps, pressure vessels, and anywhere else that two flanged components meet. The sheer number of flanged connections in a single facility means that gasket selection decisions and the quality of gasket installation have a material effect on overall plant reliability.
Not all flange gaskets are the same. The correct choice depends on flange face type, pressure class, and service conditions. In most industrial piping applications, raised face and flat face flanges require different gasket geometry and seating approaches.
Durlon® 8400 compressed non-asbestos sheet is a practical option for a wide range of flanged piping applications, offering reliable sealing performance across varying temperatures and pressures.
Understanding Full Face Gaskets and Their Applications
A full face gasket extends across the entire face of the flange, from the pipe bore to the outer bolt circle edge, with bolt holes punched through the gasket itself. This geometry distributes the sealing contact across the full face of the flange rather than concentrating it in an annular ring at the raised face.
Full face gaskets are typically used with flat face flanges, particularly when one or both flanges in the joint are made from cast iron, fiberglass, or other brittle materials. The reason is mechanical. When a raised face gasket is used against a flat face flange made from a brittle material, the compressive bolt load concentrates at the raised face contact zone, creating a bending moment that can crack the outer flange face. A full face gasket spreads that load uniformly, eliminating the stress concentration.
Typical Service Environments for Full Face Gaskets
Full face gaskets are common in lower-pressure service conditions, including water treatment systems, HVAC piping, general utilities, and process lines handling non-aggressive fluids at moderate temperatures. They are also appropriate wherever the flanges themselves are cast iron or another brittle material, regardless of the pressure rating.
In these applications, the full face gasket must be soft enough to conform to the flange face and develop adequate sealing stress without requiring excessive bolt load. Compressed non-asbestos fiber materials and rubber-based sheet gaskets are frequently used in full face configurations because they offer the necessary conformability without overly stiff construction.
When specifying a full face gasket, the inner bore diameter, outer diameter, and bolt hole pattern must match the flange dimensions precisely. A misfitted gasket will create uneven compression and uneven sealing stress, both of which increase leak risk regardless of how carefully the joint is assembled.
Key Features and Uses of Ring-Type Gaskets
A ring-type gasket occupies only the raised face area of the flange. Unlike a full face gasket, it does not extend to the bolt holes, and the bolt circle falls entirely outside the gasket’s outer diameter. The bolt load bypasses the gasket entirely, compressing it indirectly through the flange faces rather than through the gasket material itself.
This geometry has two significant advantages. First, it concentrates sealing stress in a narrower annular area, which makes it easier to achieve the contact stress required to seal against higher pressures. Second, because bolt holes don’t need to be punched through the gasket, the ring-type gasket is simpler to manufacture in a wider range of materials.
Where Ring-Type Gaskets Are Most Effective
Ring-type gaskets are the standard choice for raised-face flanges in most industrial process piping applications. They are used across petroleum refining, petrochemical processing, power generation, and other services where ASME B16.5 or B16.47 flanges are the connection standard.
In services with moderate temperature and pressure, compressed non-asbestos ring gaskets are a common choice. For higher-pressure services or applications with significant thermal cycling, flexible graphite or spiral wound ring gaskets are more appropriate because they offer better creep resistance and recovery under load cycling. The ring-type gasket must be properly centered on the raised face before bolt-up. Even minor misalignment reduces the effective sealing area, creates stress concentrations, and can lead to early gasket failure.
How Rubber Flange Gaskets Provide Reliable Sealing
Rubber flange gaskets are manufactured from elastomeric compounds that provide excellent conformability and a reliable seal at moderate temperatures and pressures. Their ability to compress and deform under bolt load allows them to fill surface irregularities on flange faces more effectively than harder materials, which makes them useful in services where flange face conditions are inconsistent or difficult to maintain.
The most common elastomers used in rubber flange gaskets include nitrile (NBR), neoprene (CR), ethylene propylene diene monomer (EPDM), and styrene-butadiene rubber (SBR). Each compound offers a different combination of chemical resistance, temperature range, and mechanical properties. Matching the elastomer to the process chemistry and temperature profile is essential.
Matching Rubber Gasket Material to Service Conditions
- Nitrile (NBR) performs well in oil, fuel, and hydrocarbon services at moderate temperatures. It is a common choice in water treatment and utility systems handling petroleum-based fluids.
- Neoprene (CR) offers good resistance to weathering, ozone, and moderate chemical exposure. It is frequently used in HVAC, refrigeration piping, and general industrial water systems.
- EPDM is well-suited for steam, hot water, and dilute acid or base services. It performs poorly with petroleum products but handles many aqueous environments effectively.
- SBR is a general-purpose option for water and lower-pressure utilities but lacks the chemical resistance of specialty elastomers.
Rubber flange gaskets are not appropriate for high-temperature services, aggressive chemical environments, or applications where creep relaxation under sustained load would result in unacceptable bolt load loss over time. Their primary strengths are conformability, low cost, and reliable sealing performance within their rated service range.
Benefits and Applications of Raised Face Flange Gaskets
A raised face flange has a small, machined elevated contact surface at the center of the flange face, surrounded by a lower outer face. When two raised face flanges are bolted together, the bolt load concentrates entirely on the raised face area, which is where the gasket sits. This focused compression makes raised face flanges more effective at developing high contact stress than flat face alternatives.
Raised face flanges are by far the most common configuration in industrial process piping, and gaskets designed for raised face use, most commonly ring-type gaskets, are correspondingly the most widely used type of gasket in piping systems across refineries, chemical plants, and power generation facilities.
Performance Advantages of Raised Face Configuration
The raised face geometry offers several sealing advantages. By limiting the seating area, it requires less total bolt load to achieve the contact stress needed to seal against a given fluid pressure. That efficiency allows raised face flanges to seal higher pressures more reliably than flat face designs with equivalent bolt loads.
In demanding services, raised face flanges are routinely paired with flexible graphite ring gaskets, spiral wound gaskets, or Durlon® 8400 compressed non-asbestos sheet cut to ring dimensions. Each of these materials offers the creep resistance and thermal stability necessary to maintain sealing contact through the temperature cycling typical of industrial process environments.
Gasket selection for raised face applications should account for the ASME seating stress requirements for the specific material. Under-stressed gaskets in raised face configurations are a common root cause of early flange leakage. Torque calculations should be verified against the gasket manufacturer’s minimum seating stress values before installation.
Exploring Flat Face Flange Gaskets and Their Uses
Flat face flanges present an entirely flat sealing surface, without the raised central contact area of the raised face design. When two flat face flanges are mated, the full face of each flange contacts the gasket uniformly. This geometry distributes bolt load across the full face area rather than concentrating it at a central ring.
Flat face flanges are commonly found in lower-pressure applications, cast iron and ductile iron piping systems, plastic-lined pipe, fiberglass reinforced pipe (FRP), and other systems where the brittle or non-metallic construction of the flange makes concentrated stress at a raised face contact zone problematic.
Gasket Selection for Flat Face Applications
Full face gaskets are the correct choice for flat face flanges in most industrial applications. A ring-type gasket used against a flat face flange creates an unbalanced load condition. The bolt load concentrates at the gasket ring, generating a bending moment on the outer flange face. In cast iron or FRP flanges, this bending moment is sufficient to crack the flange, even at relatively modest bolt torques.
In flat face piping systems handling water, utilities, or non-aggressive process fluids at lower pressures, rubber full face gaskets are frequently the right choice. They offer the conformability to develop adequate sealing stress without requiring excessive bolt load, and their softer construction reduces the risk of flange damage in cast iron or brittle material systems.
Where higher temperature or chemical resistance is needed in flat face applications, compressed non-asbestos sheet gaskets cut to full face dimensions offer better thermal stability than elastomeric options. The key is ensuring the material is soft enough to achieve proper seating stress at the bolt loads that the flange design can safely accommodate.
Matching the Right Gasket Type to Each Piping System
No single gasket type covers every service condition in industrial piping. Raised face flanges in high-pressure refinery or petrochemical service need ring-type gaskets with strong creep resistance and thermal stability. Flat face flanges in cast iron utility systems need full face gaskets soft enough to seal without stressing brittle flanges. Rubber flange gaskets are reliable within their rated range but require careful material matching to the process chemistry and temperature profile.
The cost of getting this decision wrong is not just the price of replacement gaskets. It’s the unplanned downtime, leak detection and repair obligations, safety risk, and cumulative maintenance labor that build up when sealing systems are specified without fully accounting for the operating conditions at the joint.
Facilities that reduce leak rates consistently do it by building gasket selection decisions on accurate service condition data rather than habit or availability. That means knowing the operating temperature range, pressure class, process chemistry, cycling frequency, and flange face type for each critical joint before specifying a gasket. It also means revisiting those specifications when service conditions change, not just when a gasket fails.
Durlon® 8400 is a compressed non-asbestos sheet gasket material designed to meet the demands of industrial piping applications across a broad range of service conditions.
Not Sure Which Gasket Type Fits Your Application?
Gasket selection can get complicated, especially across mixed flange types, aggressive process chemistry, or services that weren’t well-documented to begin with. The gasket materials and applications page is a good place to start, but for application-specific guidance, it helps to talk through the details with the Durlon team.
Whether you’re working on one critical joint or looking at sealing performance across an entire system in petroleum refining, chemical processing, power generation, or another tough industrial environment, we are always happy to help.