Abstract： ASME B16.20:2012 pdf download.Metallic Gaskets for Pipe Flanges. The distance of the first weld from the terminal weld shall be no greater than 38 mm (1.5 in.). Up to four additional loose preformed metal windings beyond the terminal weld m...

ASME B16.20:2012 pdf download.Metallic Gaskets for Pipe Flanges.

The distance of the first weld from the terminal weld shall be no greater than 38 mm (1.5 in.). Up to four additional loose

preformed metal windings beyond the terminal weld may be used to retain the gasket into the centering ring.

3.2.4 .ntering Ring. All spiral-wound gaskets shall he furnished assembled into a centering ring. The centering ring thickness

shall be from 2.97mm (0.117 in.) to 3.33 mm (0131 in.) and suitably grooved on the inside diameter so as to retain the gasket.

32.5 Inner Ring. Inward buckling of spiral.wound gaskets has been identified as a potential problem. Inner rings shall be furnished with all spiral-wound gaskets having PTFE (polytetrafluoroelhylene) filler material. Inner rings for flexible graphite-filled,

spiral-wound gaskets shall be furnished unless the purchaser specifies otherwise.

For all filler materials, inner rings shall be furnished in spiral-wound gaskets for

(a) NPS 24 and larger in Class 9(X)

(b) NI’S 12 and larger in Class 1500

(c) NI’S 4 arid larger In Class 2500

Inner rings are required [or these gaskets due to high available bolt loads, which may result in outer ring damage.

The inner ring thickness shall be from 197 mm to 3.33 mm (0.117 in. to 0.131 in.).

Tables 12 through 14 (Tables 1-7 through 1-9 of Mandatory Appendix I) show inner ring inside diameters that may extend a maximum of 1.5 mm (0. in.) into the flange bore under the worst combination of flange bore, eccentric installation, and tolerance.

Gaskets with inner rings should be used only with socket welding. lapped, welding neck, and integral flanges. Reference Table 15

for minimum pipe wall thickness for use with gaskets with inner rings. Reference Tables 16 through 18 (Tables 1-10 and I-il of

Mandatory Appendix I) for maximum allowable bow for use with gaskets without inner rings.

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