A Spiral wound gasket for flanges feature a metal sealing element filled with graphite, PTFE, ceramic fibers and, non-asbestos fibers (fillers). For this reason, spiral wound gaskets are classified as “semi-metallic” gaskets.
The metal component of the spiral wound gasket provides strength to the seal, whereas the fillers enhance the gasket’s conformability and resilience. Inner and outer rings can be added to the core sealing element to facilitate the installation and enhance the pressure rating. Spiral wound gaskets with graphite fillers are the most commonly sold type.
Flexitallic USA introduced spiral wound gaskets in the petrochemical industry back in 1912 to cope with an increasing demand for leak-proof seals in applications with higher and higher (and fluctuating) temperatures and pressures. Other reputable spiral wound gasket manufacturers are Garlock and Lamons.
Indeed, a spiral wound gasket is designed to withstand, better than other types of flange gaskets, the mechanical stress generated by high temperature and pressure applications. Spiral wound gasket application range, therefore, from oil and gas to power generation.
The diameter of a spiral wound gasket may range between a few mm up to 5.000 mm, and the spiral wound gasket thicknesses range from 3.2, 4.5, 6.4, to 7.2 mm.
A Spiral wound gasket may be ordered in different shapes, such as oblong, rectangular, oval, pear and diamond.
ASME B16.20 is the spiral wound gasket specification.
The round type is, of course, the standard shape for the raised face (RF), male-and-female (M&F), and tongue-and-groove flanges (T&G) for petrochemical applications.
Spiral Wound Gasket Types
A few different types of spiral wound gaskets exist, depending on:
The number of rings (outer and inner)
The materials of the inner and the outer ring of the gasket
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 specific codes to designate the different spiral wound gasket types, but the typical designs are recurring regardless of the producer.
The image shows how the different spiral wound gasket types used for flanged joints in piping applications:
Spiral Wound Gasket Materials
Spiral 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. The formed metal strip in the key sealing element of this type of semi-metallic gasket.
The most common winding materials are:
SS 304L
SS 316L
SS 321
Titanium
Nickel
Nickel alloys
Duplex
Filler Materials
Filler materials are used to enhance the conformability and the resilience of a spiral wound gasket. The most used filler material is graphite, however, other filler materials may be used depending on the application:
Graphite
PTFE
Ceramic fibers
Non-asbestos
Inner and Outer Rings Materials
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.
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 Colors
Spiral wound gaskets made with different windings and filler materials are easy to spot, as each combination is designated by the application of color codes (the main color designates the winding materials, the stripes indicate the type of filler):
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 Codes
Color Codes for Filler Materials
Polytetrafluoroethylene
PTFE
White stripe
Mica-graphite
Manufacturer’s designation
Pink stripe
Flexible graphite
F.G.
Gray stripe
Ceramic
CER
Light green stripe
Inconel 600
Inconel 600
Gold
Inconel 625
Inconel 625
Gold
Incoloy 800
Incoloy 800 H / HT
White
Incoloy 825
Incoloy 825
White
Spiral Wound Gasket Marking
The illustration shows the typical marking of spiral wound gaskets:
Spiral Wound Gaskets Dimensions
Class 150
Dimensions of class 150 spiral wound gaskets for ASME B16.5 (in mm.)
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
1¼
38.1
47.8
60.5
76.2
1½
44.5
54.1
69.9
85.9
2
55.6
69.9
85.9
104.9
2½
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.
Class 300
Dimensions of class 300 spiral wound gaskets for ASME B16.5 (in mm.)
Dimensions of spiral wound gaskets
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
1¼
38.1
47.8
60.5
82.6
1½
44.5
54.1
69.9
95.3
2
55.6
69.9
85.9
111.3
2½
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.
Class 400
Dimensions of class 400 spiral wound gaskets for ASME B16.5 (in mm.)
Dimensions of spiral wound gaskets
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
1¼
38.1
47.8
60.5
82.6
1½
44.5
54.1
69.9
95.3
2
55.6
69.9
85.9
111.3
2½
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.
Class 600
Dimensions of class 600 spiral wound gaskets for ASME B16.5 (in mm.)
Dimensions of spiral wound gaskets
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
1¼
38.1
47.8
60.5
82.6
1½
44.5
54.1
69.9
95.3
2
55.6
69.9
85.9
111.3
2½
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.
Class 900
Dimensions of class 900 spiral wound gaskets for ASME B16.5 (in mm.)
Dimensions of spiral wound gaskets
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
1¼
33.3
39.6
60.5
88.9
1½
41.4
47.8
69.9
98.6
2
52.3
58.7
85.9
143
2½
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.
Class 1500
Dimensions of class 1500 spiral wound gaskets for ASME B16.5 (in mm.)
Dimensions of spiral wound gaskets
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
1¼
33.3
39.6
60.5
88.9
1½
41.4
47.8
69.9
98.6
2
52.3
58.7
85.9
143
2½
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.
Class 2500
Dimensions of class 2500 spiral wound gaskets for ASME B16.5 (in mm.)
Dimensions of spiral wound gaskets
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
1¼
33.3
39.6
60.5
104.9
1½
41.4
47.8
69.9
117.6
2
52.3
58.7
85.9
146
2½
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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