Spiral Wound Gasket Types: CGI, CG, RIR & R Type Explained
Industrial piping systems operate under demanding combinations of pressure, temperature, vibration, thermal cycling, and aggressive process media. Selecting the correct gasket construction is therefore essential for maintaining a reliable flange seal. Among semi-metallic sealing solutions, understanding the different Spiral Wound Gasket Types helps engineers, maintenance teams, EPC contractors, and industrial buyers select the right configuration for each flange connection.
A Spiral Wound Gasket is generally manufactured by spirally winding alternating layers of preformed metallic strip and a compressible filler. Depending on the configuration, the sealing element can be supplied alone or combined with inner and outer metal rings. The four commonly recognized configurations are CGI, CG, RIR, and R. Each Spiral Wound Gasket Type offers different positioning, compression-control, and winding-protection characteristics.
ITK Gasket Industries manufactures industrial sealing products for demanding applications across chemical, petrochemical, refinery, power generation, pharmaceutical, mining, pulp and paper, and other processing sectors.
What Are the Main Spiral Wound Gasket Types?
The primary Types of Spiral Wound Gaskets can be classified according to their basic construction and the presence of inner and/or outer rings:
| Type | Construction | Common Application |
|---|---|---|
| CGI | Winding + Inner Ring + Outer Centering Ring | Raised-face and demanding services |
| CG | Winding + Outer Centering Ring | General raised-face flange applications |
| RIR | Winding + Inner Ring | Male-and-female and specialized flange arrangements |
| R | Winding Element Only | Tongue-and-groove or male-and-female arrangements |
The choice between these Different Types of Spiral Wound Gaskets should be based on flange facing, pressure class, operating temperature, process fluid, gasket material, applicable standard, and service conditions.
1. CGI – Spiral Wound Gasket with Inner and Outer Rings
CGI is one of the most comprehensive Spiral Wound Gasket Types because it incorporates the spiral wound sealing element, an outer centering ring, and a solid inner ring.
The outer ring assists with accurate positioning between the flange bolts and provides external support. The inner ring supports the internal edge of the winding, helps protect it from direct process flow, and can reduce the possibility of inward buckling.
CGI gaskets are widely considered for demanding applications involving elevated pressure, temperature cycling, aggressive fluids, and critical process connections. They are commonly associated with raised-face flange connections in refinery, chemical, petrochemical, oil and gas, and power applications.
2. CG – Spiral Wound Gasket with Outer Centering Ring
The CG configuration consists of a wound sealing element combined with an external metal centering ring. This construction makes CG one of the widely used Spiral Wound Gasket Types and Applications for general industrial piping.
The outer ring helps locate the gasket correctly on the flange face and provides radial support to the sealing element. It also assists in controlling compression during bolt tightening.
CG gaskets are commonly selected for raised-face flanges where an inner ring is not required by the applicable specification or service conditions. Applications may include water systems, steam lines, process piping, utility services, chemical plants, and general industrial flange connections.
Material selection remains important. Depending on process conditions, winding materials may include stainless steel grades and other suitable alloys, while filler options can include flexible graphite or PTFE.
3. RIR – Spiral Wound Gasket with Inner Ring
RIR is another important configuration when discussing Spiral Wound Gasket Types and Uses. It consists of the wound sealing element together with a solid metallic inner ring but does not use an external centering ring.
The inner ring occupies part of the annular space between the gasket sealing element and flange bore. It provides internal support and can help minimize direct exposure of the winding to turbulent process flow.
RIR configurations may be considered for male-and-female flange arrangements and other applications where flange geometry provides external positioning.
Because there is no external centering ring, correct dimensional specification and installation are particularly important.
4. R Type – Basic Spiral Wound Sealing Element
Style R represents the basic spiral wound construction without separate inner or outer guide rings. The inner and outer edges of the winding are typically reinforced with additional metal plies to improve stability.
This Spiral Wound Gasket Type is commonly associated with flange arrangements where the flange geometry itself positions and confines the gasket, including tongue-and-groove and certain male-and-female connections.
Unlike CG and CGI configurations, an R gasket does not have an outer centering ring for alignment. Therefore, installers must ensure that the gasket dimensions correctly correspond with the flange recess and applicable design requirements.
Spiral Wound Gasket Types and Sizes – How Are They Selected?
Selecting a gasket requires more than simply deciding between CGI, CG, RIR, and R. Under ASME B16.20, spiral wound gaskets used with applicable ASME flanges are identified according to factors such as nominal pipe size (NPS), pressure class, and flange standard.
Important selection parameters include:
- Nominal pipe size and flange pressure class
- Flange facing and applicable dimensional standard
- Operating and design pressure
- Minimum and maximum temperature
- Process fluid and chemical compatibility
- Metal winding material
- Filler material
- Inner and outer ring requirements
- Required gasket dimensions and thickness
ASME B16.20 describes spiral wound construction using alternate plies of preformed metallic winding and pliant filler. The standard also provides requirements relating to dimensions, materials, marking, rings, and performance.
Materials Used in Different Spiral Wound Gasket Types
Performance depends heavily on material compatibility. Stainless steel grades such as SS304/304L and SS316/316L are frequently considered for metallic winding, while specialized alloys may be selected for more corrosive or high-temperature environments.
Flexible graphite is widely used where good thermal resistance is required, while PTFE can be considered where chemical compatibility is particularly important. Material selection should always be based on actual process temperature, pressure, fluid chemistry, flange design, and applicable engineering specifications.
Why Choose ITK Gasket Industries?
ITK Gasket Industries supplies industrial gasket and sealing solutions for a broad range of process industries. The company states that its operations are ISO 9001:2015 certified and that its gasket and sealing components are manufactured to meet stringent international standards.
Industrial buyers can work with ITK Gasket Industries to specify the appropriate gasket construction, dimensions, winding material, filler, and ring configuration according to application requirements.
FAQs About Spiral Wound Gasket Types
Which spiral wound gasket type is commonly used for raised-face flanges?
CG and CGI configurations are commonly associated with raised-face flange applications. CGI additionally incorporates an inner ring for internal support and winding protection.
What is the difference between CG and CGI?
CG contains the wound sealing element and an outer centering ring. CGI adds a solid inner ring, providing additional internal support and protection.
What is an R type spiral wound gasket?
R type is the basic wound sealing element without separate inner or outer rings. It is commonly considered for confined flange arrangements such as tongue-and-groove and certain male-and-female connections.
What does RIR mean?
RIR refers to a configuration incorporating a wound sealing element and a solid inner metal ring. The inner ring provides internal support and helps fill the space toward the flange bore.
Which filler materials are commonly available?
Flexible graphite and PTFE are common choices. The appropriate filler depends on operating temperature, chemical compatibility, pressure, and service requirements.
How do I select between the different gasket types?
Consider flange facing, NPS, pressure class, applicable standard, operating temperature, pressure, process medium, winding alloy, filler material, and whether inner or outer rings are required.
Get the Right Spiral Wound Gasket from ITK Gasket Industries
Understanding Spiral Wound Gasket Types is essential for choosing a sealing solution that matches the flange geometry and operating environment. CGI provides both inner and outer support, CG provides external centering, RIR provides an inner supporting ring, and R offers a basic confined winding element.
For industrial projects, maintenance requirements, OEM applications, or bulk procurement, contact ITK Gasket Industries with your flange size, pressure class, flange standard, operating conditions, material preference, and required quantity. A correctly specified Spiral Wound Gasket can contribute significantly to flange sealing reliability, equipment availability, and safer plant operation.
