Spiral Wound Gaskets

Spiral Wound Gaskets

Spiral wound gaskets made by alternating a formed metal strip and a soft filler material to which form a gasket that produces a very effective seal when compressed between two flanges. The V-shaped windings of the metal strip acts as a spring, giving the gaskets greater resiliency under varying conditions.

The metal strip and filler materials of spiral wound gaskets can be changed, accommodating for different chemical compatibility requirements and fire safety is assured with selecting flexible graphite as the filler material.

Spiral wound gaskets may include a centering ring, an inner ring,or both. Spiral wound gaskets' outer centering ring ensures the gasket is centered within the flange and acts as a compression limiter. Spiral wound gasket inner rings provide additional radial strength, also reducing flange erosion while protecting the sealing element. The strength and resiliency of spiral wound gaskets make them the ideal choice in a variety of conditions and applications, and are used widely throughout refineries and chemical processing plants, also being very effective for power generation, pulp and paper, aerospace, and a variety of valve and specialty applications.

Spiral wound gaskets are manufactured to a number of specifications most notably being ASME B16.20. AIGI Environmental Inc. manufacture in accordance with the guidelines set forth in the ASME B16.20 specifications plus many others to meet industry demands.Spiral Wound Gasket Identification
Identification as Required by ASME B16.2

Gasket DimensionsSpiral Wound Gasket Types

Spiral Wound Gasket Specifications
Temperature Limits of Common Metals

Material	Minimum ^oC	Maximum ^oC	Abbreviation	Guide Ring Colour Code per ASME B16.20
304 SS	- 195	760	304	Yellow
304L SS	- 195	760	304L	No Colour
316 SS	- 100	760	316	Green
316L SS	- 100	760	316L	Maroon
321 SS	- 195	760	321	Turquoise
Carbon Steel	- 40	540	CRS	Silver
INCOLOY® 800	- 100	870	IN 800	White
INCOLOY® 825	- 100	870	IN825	White
INCONEL® 600	- 100	1,090	INC 600	Gold
INCONEL® 625	- 100	1,090	INC 625	Gold
INCONEL® X750	- 100	1,090	INX	No Colour
MONEL® 400	- 130	820	MON	Orange
Nickel 200	- 195	760	NI	Red
Titanium	- 195	2,000	TI	Purple

Temperature Limits of Filler Material

Material	Minimum ^oC	Maximum ^oC	Abbreviation	Guide Ring Colour Code per ASME B16.20
Flexible Graphite	- 212	510	F.G.	Gray
PTFE	- 240	260	PTFE	White

Available Thickness Standard Tolerances for Windings

Nominal Thickness	Compressed Thickness	Gasket Diameter	ID	OD
3.2 mm	2.4/2.6 mm	≤ 25 mm	+0.4 mm, -0	+0, - 0.8 mm
4.5 mm	3.2/3.45 mm	25 – 610 mm	+0.8 mm, -0	+0, - 0.8 mm
7.3 mm	5.0/5.25 mm	610 – 915 mm	+1.2 mm, -0	+0, - 1.6 mm
		915 – 1525 mm	+1.6 mm, -0	+0, - 1.6 mm
		1525 mm and above	+2.4 mm, -0	+0, - 2.4 mm

Gaskets in accordance with ASME B 16.20,
flanges according ASME B 16.5, measurements in inch
Gasket Type CG/CGI
*For Style CGI - see Table 3 for Inner Ring dimensions.
Gasket sizes 1/4” to 3” Class 300, 400 & 600 as well as sizes 1/2” to 2-1/2” Class 900 & 1500 are identical within their respective nominal pipe sizes therefore inventories need not be duplicated

In accordance with ASME B16.20, Inner Rings are mandatory for the following flange designations (see Table 3).
Class 900 - NPS 24 to 48
Class 1500 - NPS 12 to NPS 24
Class 2500 - NPS 4 to NPS 12
ASME B16.20 does not include dimensions for NPS 1/4, 3-1/2, or 4-1/2, or Class 400 Flanges up to NPS 3 and Class 900 Flanges up to NPS 2-1/2.

Gaskets suitable for flanges in accordance with DIN and BS4504, measurements in mm

Gaskets suitable for flanges in accordance with BS10, measurements in inch

Gaskets suitable for flanges in accordance with JIS standard, measurements in mm

Ordering Information

When ordering spiral wound gaskets please specify the following:

Gasket standard
Gasket style
Nominal pipe size and pressure rating or specific gasket dimensions if other than standard
Winding and filler materials
Outer or centering ring and /or inner ring material
Thickness of gasket if other than standard

AIGI Environmental Inc. manufactures spiral wound gaskets in accordance with all relevant international and CHinese gasket standards and non standard gaskets up to 4 meters in diameter to suit but not limited to the following flange designations:
ASME B16.5
BS 1560
BS 10
ASME B16.47 SERIES B (API 605)
ASME B16.47 SERIES A (MSS-SP 44)
BSEN 1092 (BS 4504)
DIN FLANGES
JIS FLANGES
FRENCH NF STANDARD

Please consult with AIGI Environmental Inc. for all your standard and non standard gasket requirements.
Spiral Wound Gasket Principle

The spiral wound gasket function is based on the metal strip winding / filler relatioinship and the flange surfaces. Flange surface roughness should be approximately Ra 3.2 um. Spiral wound gaskets can be used with flanges having a larger surface roughness, but the bolt loads should

be increased to ensure proper function of the gasket. As the gasket is compressed during mounting the soft filler material "flows" into the irregularities of the flange face. The metal winding strip enclosed the filler and, at the same time, ensures the strength and elasticity of the gasket. If the gasket has a PTFE filler it must have an inner ring since PTFE permits no further compression. The inner ring it prevents the gasket from springing open and penetration of the flowing PTFE into the pipeline. The larger the surface roughness on the flange face, the larger the surface load required permitting a flow of the PTFE.

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