The ASME SB462 Alloy 20Cb-3 Socket Weld Flanges are welded for the pipes. They have a socket piece welded on to them which retains the pipes in spot for ease of welding and for added power. The Alloy twenty RTJ Flange https://bushragoki327365.mpeblog.com/53297451/hastelloy-b2-sheets-and-plates-an-overview