Dimensions of Spiral Wound Gaskets for Rating 2500# as per ASME B16.20 used with Raised Face flanges ASME B16.5

Class 2500 NPS 1/2″ – 24″
NPS	Inner Ring	Sealing Element		Outer Ring
	Inside (d1)	Inside (d2)	Outside (d3)	Outside (d4)
	Dia.	Dia.mm	Dia.mm	Dia.mm
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
1-1/4	33.3	39.6	60.5	104.9
1-1/2	41.4	47.8	69.9	117.6
2	52.3	58.7	85.9	146.0
2-1/2	63.5	69.9	98.6	168.4
3	78.7	92.2	120.7	196.9
4	97.8	117.6	149.4	235.0
5	124.5	143.0	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	270.0	311.2	476.3
12	292.1	317.5	368.3	549.4

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General notes:

1. Dimensions are in millimeters unless otherwise indicated.
2. Image shows a Spiral Wound gasket with Inner – and Outer ring.
3. d1 = Inside diameter when Inner ring is used.
4. d2 = Inside diameter sealing element when no Inner ring is used.
5. d3 = Outside diameter of sealing element.
6. d4 = Outside diameter of Outer ring.
7. Thickness of inner and outer ring: 2.97 mm – 3.33 mm.
8. Thickness sealing element: 4.45 mm.
9. 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.
10. ASME B16.20 does not covers class 400 flanges up to NPS 3 and class 900 flanges up to NPS 2½.
11. 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.
12. 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.
13. 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.

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