Spiral-wound gaskets are metallic gaskets consisting of an outer centering ring (also known as OCR, or an outer guide ring), metallic windings with a soft filler material, and a solid inner ring, or any combination of the three. These gaskets are manufactured to meet specifications as outlined in ASME B16.20 (previously covered by API 601). Spiral-wound gaskets can handle more harsh and varied operating conditions than non-asbestos sheet gaskets in general. They are available in multiple materials and configurations.
TYPES OF SPIRAL-WOUNDS:
The Teadit Metalflex Style 913 Spiral-Wound Gasket (equivalent to a CG or WR gasket) consists of an outer centering ring and windings with a soft filler material. The outer centering ring (OCR) is a solid ring. It’s main purpose is to resist the pressure exerted on the windings by the process fluid. During installation, it aids in proper alignment of the gasket by fitting inside of the bolt circle of the flange. The windings are the sealing element of a spiral wound gasket. They are constructed of a metal strip wound multiple times around the inner bore of the gasket. In between each layer of winding, a soft filler material is present to aid in sealing against the irregularities of the flange faces.
The Teadit Metalflex Style 913M Spiral-Wound Gasket (equivalent to a CGI or WRI) utilizes the same outer centering ring, windings and soft filler as the Style 913 gasket, but has the added benefit of a solid inner ring. The inner ring prevents the inward buckling of the windings which can occur in a spiral-wound which does not utilize an inner ring. The inner ring also limits turbulence in the process stream by filling the gap between the flanges, and protects the windings from corrosion and/or erosion due to the process fluid. Lastly, the inner ring limits compression of the sealing element. This type of gasket is also available in a Style 913M-LSLE for extreme low-emissions, and a Style 913M-XHR for high operating temperatures.
The Teadit Style 911 spiral-wound gasket is the simplest form. It consists of only the windings with a soft filler material. Style 911 gaskets are mainly used in tongue and groove or male and female flanges. They are also used in equipment with space and weight limitations.
The Teadit Style 911M Spiral-Wound Gasket consists of the windings with soft filler, and a solid inner ring to avoid turbulence in the flow, protect against erosion and corrosion, and limit compression of the sealing element.
The Teadit Style 911T Spiral-Wound Gasket contain double jacketed bars welded into the winding. They are used in shell and tube heat exchangers with multiple passes. The bars are manufactured of the same material as the windings. The thickness of the bars are normally slightly smaller than the winding to reduce the sealing force of the gasket. A specially machined groove in the faces is needed with an appropriate compression stop is needed.
Mica Graphite 450 F Pink Flexible Graphite 842 F Gray PTFE 500 F White
Colored stripes on the outer edge of the outer ring denote the filler material.
METAL WINDING MATERIALS
Carbon Steel Economic material commonly used in metallic gaskets. Low corrosion resistance. 900 F 160 HB Silver 304 Stainless Steel 18-8 stainless steel. Relatively low-cost and excellent corrosion resistance. 790 F 160 HB Yellow 316L Stainless Steel 316 stainless steel with a Carbon content limited to a maximum of 0.03%. Because of the lower Carbon content it has less intergranular Carbon, and therefore, less intergranular corrosion. 1400 F 160 HB Green 321 Stainless Steel Austenitic stainless steel with 18% Cr and 10% Ni stabilized with Ti, which reduces intergranular Carbon precipitation and intergranular corrosion. 1500 F 160 HB Turquoise 347 Stainless Steel Similar to 304 stainless. Stabilized with Cb and Ta to reduce carbonate precipitation and intergranular corrosion. It is subject to stress corrosion. Good performance in high-temperature, corrosive service. 1500 F 160 HB Blue Monel 67% Ni and 30% Cu. It offers excellent resistance to the majority of acids and alkalis, except to extremely oxidant acids. It is subject to stress corrosion and therefore should not used in the presence of fluorine-silicon acid and mercury. In combination with PTFE, it is commonly used in severely corrosive services. 1500 F 95 HB Orange Nickel 200 99% Ni. Great corrosion resistance against caustic solutions. 1400 F 110 HB Red Inconel 77% Ni, 15% Cr and 7% Fe. Excellent corrosion resistance in temperatures ranging from cryogenic to elevated temperatures. 2000 F 150 HB Gold
The solid color on the outer edge of the outer ring denotes the winding material.
All dimensions are in inches.
ORDERING SPIRAL-WOUND GASKETS
When ordering spiral wound gaskets, the following information is needed:
- Nominal Pipe Diameter in Inches
- Flange Rating in Pounds
- Materials of Construction
- Outer Ring (or specify no outer ring)
- Filler Material
- Inner Ring (or specify no inner ring)
ALSO KNOWN AS…
Spiral wound gaskets go by many names. Many of which are related to a specific manufacturer.
Some other terms used to call out spiral-wound gaskets include:
- Semi-Metallic Gasket – Spiral wounds, because of their construction are sometimes referred to as semi-metallic gaskets.
- Ring Gasket – Because of the ring-type design, spiral wound gaskets are sometimes simply called ring gaskets. Ring gasket can also refer to a ring-type gasket, cut from flat non-asbestos, PTFE, or rubber sheet.
- Flexitallic Gasket – Broad term sometimes used to describe nearly any type of spiral wound gasket. Flexitallic is actually a manufacturer of spiral wound gaskets.
- CG Gasket – A style of Flexitallic gasket. Describes a spiral wound gasket with an outer ring, but no inner ring, i.e. Teadit Style 913.
- CGI Gasket- A style of Flexitallic gasket. Describes a spiral wound gasket with both an outer ring, and an inner ring, i.e. Teadit Style 913M.
- WR Gasket – A style of Lamons gasket. Describes a spiral wound gasket with an outer ring, but no inner ring, i.e. Teadit Style 913.
- WRI Gasket – A style of Lamons gasket. Describes a spiral wound gasket with both an outer ring, and an inner ring, i.e. Teadit Style 913M.
Sources: Teadit North America Technical Engineering Catalog, ASME B16.20
Note: All material included on this page is informational only, and should not be used as one’s sole source for design purposes. STS Industrial, Inc. and its affiliates do not guarantee the accuracy of the information on this site, and retain no liability for the use or misuse of the information contained on this site.