Dims of Spiral Wound Gaskets ASME B16.20 used with Raised Face flanges ASME B16.5

Other Pressure Classes

NPS	Inner Ring	Sealing Element		Outer Ring
	d1	d2	d3	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

General notes:

• Dimensions are in millimeters unless otherwise indicated.
• Image shows a Spiral Wound gasket with Inner - and Outer ring.
• d1 = Inside diameter when Inner ring is used.
• d2 = Inside diameter sealing element when no Inner ring is used.
• d3 = Outside diameter of sealing element.
• d4 = Outside diameter of Outer ring.
• 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 trough NPS 24 tolerance is + 1.5 mm - 0.8 mm.
• ASME B16.20 does not covers class 400 flanges up to NPS 3 and class 900 flanges up to NPS 2½.
• There are 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.
• The inner ring inside diameters shown for NPS 1¼ thru 2½ in class 1500 and 2500 will produce inner ring widths of 0.12 inches, a practical minimum for production purposes.
• ASME B16.20 which covers spiral wound gaskets requires the use of solid metal inner rings in: Pressure Class 900, nominal pipe sizes 24 and larger, Pressure Class 1500 from nominal pipe sizes 12 and larger, Pressure Class 2500 from nominal pipe sizes 4 and larger and all PTFE filled gaskets.