Chapter 4.2 - Flange and Component Systems

Abstract

This chapter provides an introduction to various types of flanges and their component systems. One of the types of flanges—beaded-edge face-sealed flanges—is made up of two identical flanges, a gasket, and a male and a female nut. The nuts are installed before the flanges are welded into place. On the face of each flange is a raised bead of semicircular cross section. ConFlat® (CF) series of metal sealed flanges are introduced for ultrahigh vacuum applications. There are interchangeable flanges, often referred to as CF flanges. The flanges are commercially available in a variety of stainless steel alloys and aluminum. Aluminum flanges have a hard coating over the flange face and knife edge so that the knife edge is hard enough to penetrate the gasket without damage. The bolts in a CF joint should be the same alloy as the flanges to ensure uniform expansion during bakeout. American Standards Association (ASA) or American National Standards Institute (ANSI) flanges are one of the oldest flange systems used in building metal vacuum systems in the United States. ASA (ANSI) flanges remain an option on many types of high-vacuum pumps. These flanges are adapted to vacuum service from the 150-lb ASA (ANSI) flanges used with steam or compressed air. They are O-ring sealed, held together with bolts and are available for tubing sizes from 1.5 inches to 12 inches.