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Technical Notes




Flanges & Components > Technical Notes


ISO Flanges

ISO flanges (also called Large ISO) have a sexless design and are made from 304L stainless or aluminum.

The design principles of ISO and KF seals are identical. Each flange face is counter-bored or grooved to receive a metal centering ring with an elastomeric o-ring around its O.D. As with KF, the ISO centering ring both aligns the flanges and holds the o-ring in place. However, because the larger diameter ISO o-ring is more likely to "roll off," a spring-loaded retainer holds it externally. ISO flanges are limited (by the o-ring’s properties) to applications with temperatures between ~0° C and 120–180° C, and pressure from atmosphere to ~10-8 Torr or mbar. ISO flanges are universally sized by the nominal I.D. (in, mm) of the largest tube that can be welded to the flange. The standard sizes are: 63, 80, 100, 160, 200, 250, 320, 400, 500, and 630.

The ISO-K is convenient and has the smallest flange O.D. for any given tube I.D. The ISO-F offers greater strength when used as a structural element.

A variety of bolt/clamp options permit joints between mixed ISO-K and -F flanges. The illustrations (Figures 1-4) show various possible clamping arrangements.

ISO Double Clamp Nipple Assemble ISO Bolt Nipple Assembly ISO Single Clamp/Bolt Nipple Assembly ISO Bolt Ring Nipple Assembly

Figure 1: ISO Double Clamp Nipple Assembly

Figure 2: ISO Bolt Nipple
Assembly

Figure 3: ISO Single Clamp/Bolt Nipple Assembly

Figure 4: ISO Bolt Ring Nipple Assembly

Two flange "styles":

  • ISO-K flanges(Figure 5): use separate clamps placed around the flange’s periphery
  • ISO-F flanges(Figure 6): use conventional bolt holes and nuts/bolts

ISO100 K-Style Flange & Hardware ISO63 "F" & "K" Style Flanges

Figure 5: ISO100 K-Style Flange & Hardware

Figure 6: ISO63 "F" & "K" Style Flanges


Table 1: Centering Ring Dimensions

Size Lip O.D. in.(mm) Lip I.D. in.(mm) Thickness in.(mm)
ISO 63 2.756 (70) 2.63 (66.8) 0.154 (3.9)
ISO 80 3.268 (83) 3.14 (79.8) 0.154 (3.9)
ISO 100 4.016 (102) 3.89 (98.8) 0.154 (3.9)
ISO 160 6.024(153) 5.90 (149.9) 0.154 (3.9)
ISO 200 8.386 (213) 8.26 (209.8) 0.154 (3.9)
ISO 250 10.276 (261) 10.14 (257.6) 0.154 (3.9)
ISO 320 12.520 (318) 12.30 (312.4) 0.220 (5.6)
ISO 400 15.748 (400) 15.53 (394.5) 0.220 (5.6)
ISO 500 19.724 (501) 19.51 (495.6) 0.220 (5.6)
ISO 630 25.630 (651) 25.41 (645.4) 0.220 (5.6)

Table 2: ISO K-Style Flange Dimensions

Flange Size Tube O.D. (in.) Flange O.D. in.(mm) Flange Thickness in.(mm) Number of Clamps Assembly Diameter in.(mm)
Minimal Optimal
ISO 63 2 -1/2 3.74 (95) 0.47 (12) 3 4 5.00 (127)
ISO 80 3 4.33 (110) 0.47 (12) 4 8 5.59 (142)
ISO 100 4 5.12 (130) 0.47 (12) 4 8 6.38 (162)
ISO 160 6 7.09 (180) 0.47 (12) 4 8 8.35 (212)
ISO 200 8 9.45 (240) 0.47 (12) 6 12 10.71 (272)
ISO 250 10 11.42 (290) 0.47 (12) 6 12 12.68 (322)
ISO 320 12 -3/4 14.57 (370) 0.67 (17) 8 12 16.73 (425)
ISO 400 16 17.72 (450) 0.67 (17) 8 16 20.08 (510)
ISO 500 20 21.65 (550) 0.67 (17) 12 16 24.02 (610)
ISO 630 24 27.17 (690) 0.86 (22) 14 18 29.53 (750)

Table 3: ISO F-Style Flange Dimensions

Flange Size Tube O.D. (in.) Flange O.D. in.(mm) Flange Thickness in.(mm) No. of Bolts Holes Diameter in.(mm) BCD in.(mm)
ISO 63 2 -1/2 5.12 (130) 0.47 (12) 4 0.35 (9) 4.33 (110)
ISO 80 3 5.71 (145) 0.47 (12) 8 0.35 (9) 4.92 (125)
ISO 100 4 6.50 (165) 0.47 (12) 8 0.35 (9) 5.71 (145)
ISO 160 6 8.86 (225) 0.63 (16) 8 0.43 (11) 7.87 (200)
ISO 200 8 11.22 (285) 0.63 (16) 12 0.43 (11) 10.24 (260)
ISO 250 10 13.19 (335) 0.63 (16) 12 0.43 (11) 12.20 (310)
ISO 320 12 -3/4 16.73 (425) 0.79 (20) 12 0.55 (14) 15.55 (395)
ISO 400 16 20.08 (510) 0.79 (20) 16 0.55 (14) 18.90 (480)
ISO 500 20 24.02 (610) 0.79 (20) 16 0.55 (14) 22.83 (580)
ISO 630 24 29.53 (750) 0.95 (24) 20 0.55 (14) 28.35 (720)

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