Spiral wound gaskets are “semi-metallic” gaskets whose sealing element is a metal strip filled with graphite, PTFE, ceramic fibers and, non-asbestos fibers (filler materials). The metal component of the spiral wound gasket provides strength to the seal, whereas the added fibers enhance conformability and resilience. Inner and outer rings can be added to the core sealing element to facilitate the installation and enhance pressure rating. 

 

The dimensions of spiral wound gaskets range from a few mm up to 5.000 mm, and the typical thicknesses are 3.2, 4.5, 6.4, and 7.2 mm.

A Spiral wound gasket may be ordered with different shapes, such as oblong, rectangular, oval, pear and diamond. The round type is, of course, the standard shape for raised face (RF), male-and-female (M&F), and tongue-and-groove flanges (T&G) for petrochemical applications.

Flexitallic USA introduced spiral wound gaskets in the petrochemical market back in 1912 to cope with an increasing demand for leak-proof sealing solutions in applications with higher and higher (and fluctuating) temperatures and pressures. Spiral wound gaskets are designed to withstand the mechanical stress generated by severe service conditions of pipeline’s flanged joints with enhanced features than compressed fiber gaskets.

 

flexitallic

 

 

SPIRAL WOUND GASKET TYPES

Spiral wound gaskets are available in different designs depending on:

  • the number of rings (outer and inner)
  • the materials of the inner and the outer ring of the gasket

spiral wound gaskets types

  • Type 00: Spiral Wound Gasket without rings: they are used for tongue and groove, male and female flanges.
  • Type 01: Spiral Wound Gasket with inner ring: they are used for male and female or special flange types.
  • Type 10: Spiral Wound Gasket with outer ring: they are used for raised face flanges.
  • Type 101: Spiral Wound Gasket with inner and outer rings: they are used for raised face flanges.
  • Special Section: Spiral Wound Gasket with special rings: they are used for special flanges and special usage.

Each manufacturer, of course, has a specific way to code such configurations of spiral wound gaskets.

The image shows how the different available types of spiral wound gaskets fit a flanged connection:

types of SW gaskets

 

MATERIALS FOR SPIRAL WOUND GASKET

Section of spiral wound gasket

SPIRAL WOUND GASKET WINDING MATERIALS

The sealing element of a spiral wound gasket is produced by interleaving plies of alternating metal winding strip combined with a filler material. Such formed metal strip in the key sealing element of a spiral wound gasket. The filler material used for the metal strip is usually graphite, even if different materials such as PTFE, ceramic fibers, and non-asbestos materials may be used.

  • SS 304L
  • SS 316L
  • SS 321
  • Titanium
  • Nickel
  • Nickel alloys
  • Duplex

FILLER MATERIALS FOR SPIRAL WOUND GASKET

  • Graphite
  • PTFE
  • Ceramic fibers
  • Non-asbestos

MATERIALS FOR INNER AND OUTER RINGS

The inner and the outer rings of a spiral wound gasket may be the same material of the winding core or a different one. Solid inner rings are required by the ASME B16.20 specification for flanges with pressure rating 900# NPS 24 and larger, 1500# NPS 12 and larger, pressure class 2500#, NPS 4 and larger. The inner ring improves the pressure rating of the spiral wound gasket, as it provides additional compression to the flanged joint and provides a heat and corrosion barrier protecting the gasket windings and the flanges from erosion.

 

SPIRAL WOUND GASKET MATERIALS MECHANICAL PROPERTIES

Spiral Wound Gasket Material
(Commercial Name)
DIN
SPECIFICATION
DIN
MATERIAL NR.
AISI &
UNS
B.S &
ASTM
HARDNESS
HV 10
TEMPERATURE RANGE in C° VOLUMETRIC MASS [G/CM3]
MIN. MAX.
Soft Iron (Armco) 1.1003 90 – 100 -60 500 7.85
Steel (LCS) RSt.37.2 1.0038 100 – 130 -40 500 7.85
Stainless Steel 304 X5CrNi 18 1.4301 304 304S15/16/31 130 – 180 -250 550 7,9
Stainless Steel 304 L X2CrNi 189 1.4306 304L 304S11 130 – 190 -250 550 7,9
Stainless Steel 309 X15CrNiMo 2012 1.4828 309 309S24 130 – 190 -100 1000 7,9
Stainless Steel 316 X5CrNiMo 1810 1.4401 316 316S31/33 130 – 180 -100 550 7,9
Stainless Steel 316 L X2CrNiMo 1810 1.4404 316L 316S11/13 130 – 190 -100 550 7,9
Stainless Steel 316 Ti X10CrNiMoTi 1810 1.4571 316Ti 320S31 130 – 190 -100 550 7,8
Stainless Steel 321 X10CrNiTi 189 1.4541 321 321S12/49/87 130 – 190 -250 550 7,9
Stainless Steel 347 X10CrNiNb 189 1.4550 347 347S31 130 – 190 -250 550 7,9
Nickel 200 Ni 99.2 2,4066 NO2200 3072-76 NA11 90 – 120 -250 600 8,9
Monel 400 NiCu 30 Fe 2.4360 NO4400 3072-76 NA13 110 – 150 -125 600 8,8
Inconel 600 NiCr 15 Fe 2.4816 NO6600 3072-76 NA14 120 – 180 -100 950 8,4
Incoloy 800 X10NiCrAITi 3220 1.4876 NO8800 3072-76 NA15 140 – 220 -100 850 8,4
Incoloy 825 NiCR 21 Mo 2.4858 NO8825 3072-76 NA 16 120 – 180 -100 450 8,14
Hastelloy B2 NMo 28 2.4617 N10665 170 – 230 -200 450 9,2
Hastelloy C276 ‘NiMo 16Cr15W 2.4819 N10276 170 – 230 -200 450 8.9
Titanium Ti 99,8 3.7025 110 – 140 -250 500 4,5

 

SPIRAL WOUND GASKET COLOR CODES

Spiral wound gaskets feature colored markings for the winding and the non-metallic fillers

Spiral Wound Gaskets Color Coding

  • Metallic winding materials: the metallic winding material is designated by a solid color identification around the outside edge of the centering, as shown in the image below
  • Non-metallic filler color coding: the gasket filler materials are designated by a number of stripes placed at equal distances around the edge of the centering ring

Spiral Wound Gasket Color Coding

 

WINDING MATERIALS COLOR CODING

Metallic Winding Material for Spiral Wound Gasket Abbreviated Winding
Material Name
Color Code
Carbon steel CRS Silver
304 SS 304 Yellow
304 L SS 304 L No color
309 SS 309 No color
316 L SS 316 L Green
347 SS 347 Blue
321 SS 321 Turquoise
Monel 400 MON Orange
Nickel 200 NI Red
Titanium TI Purple
Hastelloy B HAST B Brown
Hastelloy C HAST C Beige

 

FILLER MATERIALS COLOR CODING

Polytetrafluoroethylene PTFE White stripe
Mica-graphite Manufacturer’s designation Pink stripe
Flexible graphite F.G. Gray stripe
Ceramic CER Light green stripe

 

Inconel 600 INC 600 Gold
Inconel 625 INC 625 Gold
Incoloy 800 IN 800 White
Incoloy 825 IN 825 White

 

MARKINGS ON SPIRAL WOUND GASKET

The illustration shows the configuration of a typical spiral wound gaskets and the usual manufacturers’ markings:

Spiral wound gasket marking

 

 

SPIRAL WOUND GASKET DIMENSIONS (ASME B16.20 FOR ASME B16.5 FLANGES)

Spiral Wound Gasket Class 150 Dimensions

Spiral wound gaskets dimensions
Spiral wound gaskets dimensions
NPS Inner Ring Sealing Element Outer Ring
Inside Diameter (d1) Inside Diameter (d2) Outside Diameter(d3) Outside Diameter (d4)
1/2 14.2 19.1 31.8 47.8
3/4 20.6 25.4 39.6 57.2
1 26.9 31.8 47.8 66.8
38.1 47.8 60.5 76.2
44.5 54.1 69.9 85.9
2 55.6 69.9 85.9 104.9
66.5 82.6 98.6 124
3 81 101.6 120.7 136.7
4 106.4 127 149.4 174.8
5 131.8 155.7 177.8 196.9
6 157.2 182.6 209.6 222.3
8 215.9 233.4 263.7 279.4
10 268.2 287.3 317.5 339.9
12 317.5 339.9 374.7 409.7
14 349.3 371.6 406.4 450.9
16 400.1 422.4 463.6 514.4
18 449.3 474.7 527.1 549.4
20 500.1 525.5 577.9 606.6
24 603.3 628.7 685.8 717.6

NOTES: • All dimensions are in millimeters • Spiral Wound gasket with Inner – and Outer ring • d1 = Inside diameter Inner ring. • d2 = Inside diameter sealing element when no Inner ring is used. • d3 = Outside diameter of sealing element. • d4 = Outside diameter of an Outer ring

The thickness of inner and outer ring: 2.97 mm – 3.33 mm. • Thickness sealing element: 4.45 mm. • Tolerance Outside diameter for NPS 1/2 through NPS 8 is ± 0.8 mm; for NPS 10 through NPS 24 tolerance is + 1.5 mm – 0.8 mm. • There is no class 400 flanges NPS 1/2 thru NPS 3 (use Class 600), class 900 flanges NPS 1/2 thru NPS 2½ (use Class 1500), or class 2500 flanges NPS 14 or larger. 

 

Spiral Wound Gasket Class 300 Dimensions

spiral wound gasket dimensions

NPS Inner Ring Sealing Element Outer Ring
Inside Diameter (d1) Inside Diameter (d2) Outside Diameter (d3) Outside Diameter (d4)
1/2 14.2 19.1 31.8 54.1
3/4 20.6 25.4 39.6 66.8
1 26.9 31.8 47.8 73.2
38.1 47.8 60.5 82.6
44.5 54.1 69.9 95.3
2 55.6 69.9 85.9 111.3
66.5 82.6 98.6 130.3
3 81 101.6 120.7 149.4
4 106.4 127 149.4 181.1
5 131.8 155.7 177.8 215.9
6 157.2 182.6 209.6 251
8 215.9 233.4 263.7 308.1
10 268.2 287.3 317.5 362
12 317.5 339.9 374.7 422.4
14 349.3 371.6 406.4 485.9
16 400.1 422.4 463.6 539.8
18 449.3 474.7 527.1 596.9
20 500.1 525.6 577.9 654.1
24 603.3 628.7 685.8 774.7

NOTES: • All dimensions are in millimeters • Spiral Wound gasket with Inner – and Outer ring • d1 = Inside diameter Inner ring. • d2 = Inside diameter sealing element when no Inner ring is used. • d3 = Outside diameter of sealing element. • d4 = Outside diameter of an Outer ring

The thickness of inner and outer ring: 2.97 mm – 3.33 mm. • Thickness sealing element: 4.45 mm. • Tolerance Outside diameter for NPS 1/2 through NPS 8 is ± 0.8 mm; for NPS 10 through NPS 24 tolerance is + 1.5 mm – 0.8 mm. • There is no class 400 flanges NPS 1/2 thru NPS 3 (use Class 600), class 900 flanges NPS 1/2 thru NPS 2½ (use Class 1500), or class 2500 flanges NPS 14 or larger. 

 

Spiral Wound Gasket Class 400 Dimensions

spiral wound gasket dimensions

NPS Inner Ring Sealing Element Outer Ring
Inside Diameter (d1) Inside Diameter (d2) Outside Diameter (d3) Outside Diameter (d4)
1/2 14.2 19.1 31.8 54.1
3/4 20.6 25.4 39.6 66.8
1 26.9 31.8 47.8 73.2
38.1 47.8 60.5 82.6
44.5 54.1 69.9 95.3
2 55.6 69.9 85.9 111.3
66.5 82.6 98.6 130.3
3 81 101.6 120.7 149.4
4 102.6 120.7 149.4 177.8
5 128.3 147.6 177.8 212.9
6 154.9 174.8 209.6 247.7
8 205.7 225.6 263.7 304.8
10 255.3 274.6 317.5 358.9
12 307.3 327.2 374.7 419.1
14 342.9 362 406.4 482.6
16 389.9 412.8 463.6 536.7
18 438.2 469.9 527.1 593.9
20 489 520.7 577.9 647.7
24 590.6 628.7 685.8 768.4

NOTES: • All dimensions are in millimeters • Spiral Wound gasket with Inner – and Outer ring • d1 = Inside diameter Inner ring. • d2 = Inside diameter sealing element when no Inner ring is used. • d3 = Outside diameter of sealing element. • d4 = Outside diameter of an Outer ring

The thickness of inner and outer ring: 2.97 mm – 3.33 mm. • Thickness sealing element: 4.45 mm. • Tolerance Outside diameter for NPS 1/2 through NPS 8 is ± 0.8 mm; for NPS 10 through NPS 24 tolerance is + 1.5 mm – 0.8 mm. • There is no class 400 flanges NPS 1/2 thru NPS 3 (use Class 600), class 900 flanges NPS 1/2 thru NPS 2½ (use Class 1500), or class 2500 flanges NPS 14 or larger. 

 

Spiral Wound Gasket Class 600 Dimensions

spiral wound gasket dimensions

NPS Inner Ring Sealing Element Outer Ring
Inside Diameter (d1) Inside Diameter (d2) Outside Diameter (d3) Outside Diameter (d4)
1/2 14.2 19.1 31.8 54.1
3/4 20.6 25.4 39.6 66.8
1 26.9 31.8 47.8 73.2
38.1 47.8 60.5 82.6
44.5 54.1 69.9 95.3
2 55.6 69.9 85.9 111.3
66.5 82.6 98.6 130.3
3 78.7 101.6 120.7 149.4
4 102.6 120.7 149.4 193.8
5 128.3 147.6 177.8 241.3
6 154.9 174.8 209.6 266.7
8 205.7 225.6 263.7 320.8
10 255.3 274.6 317.5 400.1
12 307.3 327.2 374.7 457.2
14 342.9 362 406.4 492.3
16 389.9 412.8 463.6 565.2
18 438.2 469.9 527.1 612.9
20 489 520.7 577.9 682.8
24 590.6 628.7 685.8 790.7

NOTES: • All dimensions are in millimeters • Spiral Wound gasket with Inner – and Outer ring • d1 = Inside diameter Inner ring. • d2 = Inside diameter sealing element when no Inner ring is used. • d3 = Outside diameter of sealing element. • d4 = Outside diameter of an Outer ring

The thickness of inner and outer ring: 2.97 mm – 3.33 mm. • Thickness sealing element: 4.45 mm. • Tolerance Outside diameter for NPS 1/2 through NPS 8 is ± 0.8 mm; for NPS 10 through NPS 24 tolerance is + 1.5 mm – 0.8 mm. • There is no class 400 flanges NPS 1/2 thru NPS 3 (use Class 600), class 900 flanges NPS 1/2 thru NPS 2½ (use Class 1500), or class 2500 flanges NPS 14 or larger. 

 

Spiral Wound Gasket Class 900 Dimensions

spiral wound gasket dimensions

NPS Inner Ring Sealing Element Outer Ring
Inside Diameter (d1)  Inside Diameter (d2)  Outside Diameter(d3)  Outside Diameter (d4)
1/2 14.2 19.1 31.8 63.5
3/4 20.6 25.4 39.6 69.9
1 26.9 31.8 47.8 79.5
33.3 39.6 60.5 88.9
41.4 47.8 69.9 98.6
2 52.3 58.7 85.9 143
63.5 69.9 98.6 165.1
3 78.7 95.3 120.7 168.4
4 102.6 120.7 149.4 206.5
5 128.3 147.6 177.8 247.7
6 154.9 174.8 209.6 289.1
8 196.9 222.3 257.3 358.9
10 246.1 276.4 311.2 435.1
12 292.1 323.9 368.3 498.6
14 320.8 355.6 400.1 520.7
16 374.7 412.8 457.2 574.8
18 425.5 463.6 520.7 638.3
20 482.6 520.7 571.5 698.5
24 590.6 628.7 679.5 838.2

NOTES: • All dimensions are in millimeters • Spiral Wound gasket with Inner – and Outer ring • d1 = Inside diameter Inner ring. • d2 = Inside diameter sealing element when no Inner ring is used. • d3 = Outside diameter of sealing element. • d4 = Outside diameter of an Outer ring

The thickness of inner and outer ring: 2.97 mm – 3.33 mm. • Thickness sealing element: 4.45 mm. • Tolerance Outside diameter for NPS 1/2 through NPS 8 is ± 0.8 mm; for NPS 10 through NPS 24 tolerance is + 1.5 mm – 0.8 mm. • There is no class 400 flanges NPS 1/2 thru NPS 3 (use Class 600), class 900 flanges NPS 1/2 thru NPS 2½ (use Class 1500), or class 2500 flanges NPS 14 or larger. 

 

Spiral Wound Gasket Class 1500 Dimensions

spiral wound gasket dimensions

NPS Inner Ring Sealing Element Outer Ring
Inside Diameter (d1)   Inside Diameter (d2)  Outside Diameter(d3)  Outside Diameter (d4)
1/2 14.2 19.1 31.8 63.5
3/4 20.6 25.4 39.6 69.9
1 26.9 31.8 47.8 79.5
33.3 39.6 60.5 88.9
41.4 47.8 69.9 98.6
2 52.3 58.7 85.9 143
63.5 69.9 98.6 165.1
3 78.7 92.2 120.7 174.8
4 97.8 117.6 149.4 209.6
5 124.5 143 177.8 254
6 147.3 171.5 209.6 282.7
8 196.9 215.9 257.3 352.6
10 246.1 266.7 311.2 435.1
12 292.1 323.9 368.3 520.7
14 320.8 362 400.1 577.9
16 374.7 406.4 457.2 641.4
18 425.5 463.6 520.7 704.9
20 476.3 514.4 571.5 755.7
24 577.9 616 679.5 901.7
NOTES: • All dimensions are in millimeters • Spiral Wound gasket with Inner – and Outer ring • d1 = Inside diameter Inner ring. • d2 = Inside diameter sealing element when no Inner ring is used. • d3 = Outside diameter of sealing element. • d4 = Outside diameter of an Outer ring

The thickness of inner and outer ring: 2.97 mm – 3.33 mm. • Thickness sealing element: 4.45 mm. • Tolerance Outside diameter for NPS 1/2 through NPS 8 is ± 0.8 mm; for NPS 10 through NPS 24 tolerance is + 1.5 mm – 0.8 mm. • There is no class 400 flanges NPS 1/2 thru NPS 3 (use Class 600), class 900 flanges NPS 1/2 thru NPS 2½ (use Class 1500), or class 2500 flanges NPS 14 or larger. 

 

Spiral Wound Gasket Class 2500 Dimensions

spiral wound gasket dimensions

NPS Inner Ring Sealing Element Outer Ring
 Inside Diameter (d1)  Inside Diameter (d2)  Outside Diameter(d3)  Outside Diameter (d4)
1/2 14.2 19.1 31.8 69.9
3/4 20.6 25.4 39.6 76.2
1 26.9 31.8 47.8 85.9
33.3 39.6 60.5 104.9
41.4 47.8 69.9 117.6
2 52.3 58.7 85.9 146
63.5 69.9 98.6 168.4
3 78.7 92.2 120.7 196.9
4 97.8 117.6 149.4 235
5 124.5 143 177.8 279.4
6 147.3 171.5 209.6 317.5
8 196.9 215.9 257.3 387.4
10 246.1 270 311.2 476.3
12 292.1 317.5 368.3 549.4

NOTES: • All dimensions are in millimeters • Spiral Wound gasket with Inner – and Outer ring • d1 = Inside diameter Inner ring. • d2 = Inside diameter sealing element when no Inner ring is used. • d3 = Outside diameter of sealing element. • d4 = Outside diameter of an Outer ring

The thickness of inner and outer ring: 2.97 mm – 3.33 mm. • Thickness sealing element: 4.45 mm. • Tolerance Outside diameter for NPS 1/2 through NPS 8 is ± 0.8 mm; for NPS 10 through NPS 24 tolerance is + 1.5 mm – 0.8 mm. • There is no class 400 flanges NPS 1/2 thru NPS 3 (use Class 600), class 900 flanges NPS 1/2 thru NPS 2½ (use Class 1500), or class 2500 flanges NPS 14 or larger. 

 

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