ASME B16.20:1998 pdf download METALLIE GASKETS FOR PIPE FLANGES Ri n g-Joint, Spiral-Wound, and Jackeltd
2.7 Identification Number
Dimensional reference identification numbers are assigned to ring-joint gaskets and are shown in Tables3 through 8.
3 SPIRAL-WOUND GASKETS
3.1 Size and Class
Spiral-wound gaskets,including centering ring andinner ring (paras. 3.2.4 and 3.2.5),are identified byflange size (NPS)pressure class，and the appropriatcflange standard (ASMF B16.5 or ASME BI6.47).
3.2 Dimensions and Tolerances
3.2.1 General. Dimensions and tolerances for spi-ral-wound gaskets, centering rings, and inner rings shallbe in accordance with Tables 9 through Il and asspecified in this section.
3.2.2 Construction. Spiral-wound gaskets shall bcconstructed as alternate plies (circular layers countedas revolutions) of preformed metal windings and plaintfillers that are spirally wound. For the finished gaskel.the filler shall be essentially flush with, but not belowthe metal winding on both contact faces of the gasket.The metal strip in the winding shall be 0.006 in. to0.009 in. thick. The fller material thickness shall bedetermined by the manufacturer.
3.2.3 Metal Joining. The inner windings shallhave a minimum of three plies of preformed metalstrip without filler. The initial two plies shall be spot-welded circumferentially with a minimum of threewelds spaced at a maximum distance of 3 in.The outcr windings, which shall have a minimum of threeplies of preformed melal without filler, shall be spotwelded circumferentially with a minimum of threewelds. the last of which shall be the terminal weld.The distance of the first weld from the terminal weldshall be no greater than 1.5 in.Up to four additionalloosc preformed metal windings beyond the terminalweld may be used to retain the gasket into the centering ring.
3.2.4 Centering Ring. All spiral-wound gaskctsshall be furnished assembled into a centering ring. Thecentcring ring thickness shall be from 0.117 in. to0.131 in. and suitably grooved on the inside diarneterso as to rctain thc gaskcl.
3.2.5 Inner Ring. Inner rings shall be furnishedwith all spiral-wound gaskets having PTFE (polytetrafluoroethylene) filler material. t is recommended thatinncr rings bc specificd by the uscr for flcxiblc graphitcand other filler materials (if appropriate for flanges andbore sizes used), particularly where experience hasdemonstruted inward buckling of the gaskets to be aproblem. Inner rings shall be furnished in spiral-woundgaskets for flanges NPS 24 and larger in Class 900.NPS 12 and larger in Class 1500.and NPS 4 andlarger in Class 2500. Gaskets with inner rings shouldbe used only with socket welding, lapped, weldingneck. and integral fanges.
The inner-ring thickness shall be from 0.117 in. to0.131 in. Tables 12 through 14 show inner-ring insidediamcters that may extend a maximum of 0.06 in. intothe flange bore under the worst combination of flangebore. eccentric installation、and tolerance. ReferenceTable 15 for minimum pipe wall thickness for use withgaskets with inner rings. Reference Tables 16，17，and18 for maximum allowable borc for use with gasketswithout inner rings.
3.2.6 Gasket Compression.Spiral-wound gasketsNPS 人.NPS 7.and NPS I in Classes 150.300,and6() shall be designed so that a uniform bolt stress of25,000 psi.based on the nominal bolt root diameter.will compress the gasket to a thickness of 0.130 in:0.005 in.All other gasket sizes and classes shall bedesigned so that a uniform bolt stress of 30,000 psiwitl compress the gasket to a thickness of 0.130 in.+0.005 in.
ASME B16.20:1998 pdf download
PS:Thank you for your support!
