ISO HV Flanges Technical Notes

ISO HV 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 HV 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 HV 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.

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

Figure 5:
ISO100 K-Style Flange & Hardware

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

Table 1: Centering Ring Dimensions

Table 2: ISO K-Style Flange Dimensions

Table 3: ISO F-Style Flange Dimensions