The 100762450 Bored Bolted Flange is used for internal welding of 20 inch outside diameter vacuum tube or pipe to a size NW500 ISO-BF bolted vacuum flange. Series 76 ISO-BF components feature a vacuum flanging system for 63 mm to 630 mm fittings with flange dimensions meeting the requirements established by the International Standards Organization (ISO). They function as modular building blocks in vacuum piping systems and are compatible with ISO compliant components from other manufacturers. ISO-BF flanges are “sexless” with the seal on a symmetrical centering ring that interfaces with two identical size ISO flanges. ISO-BF flanges are more compact than ASA flanges, which were designed for pressure and are unnecessarily massive for vacuum use. The Series 76 ISO-BF flanges can be joined to ISO-MF flanges by using a rotatable bolt ring on the ISO-MF flange or to other ISO-BF flanges by simply bolting together. Applications ISO universal components include roughing and foreline plumbing, high-vacuum, high-conductance interconnections, modular systems needing frequent modifications, and research laboratories.