These ISO-LF DN 400 weld-on, tapped M12 x 1.75, 304 stainless steel bulkhead flanges are designed to be welded directly to the side of a stainless steel vacuum chamber wall with a port cut out diameter equal to the inside diameter of the flange (see dimensions below). The flange is welded to the chamber on the inside port which makes a perfect vacuum seal.

These bulkhead flanges have threaded through holes. Once the flange is welded to the chamber wall, the chamber wall becomes the thread bottom. So, the flange's through holes become blind holes with a thread depth equal to the flange's thickness.

These flanges can be used with ISO-F bolted and ISO-K claw clamped flanges of the same ISO size. To connect ISO-K bolted flanges or fittings, use silver plated bulkhead bolts to prevent galling or seizing of the bolts and to make them easier to loosen, especially if they will be heated to bakeout temperatures (part number P1013041). To connect ISO-K type flanges or fittings, use single claw clamps (part number P1012717) with anti seize thread lubricant. Either connection type requires a centering ring with O-ring seal (part number P1012723).

Bulkhead flanges offer the highest possible conductance by minimizing the port length which preserves maximum vacuum throughput and pumping speed. 3D CAD models are available in the download section.