Y- strainers are available in a wide variety of end types. iron and bronze are almost always supplied with threaded or flanged end connections. Carbon steel and stainless are also furnished in these end connection types. In all cases, flanges are designed to ANSI specifications. Special flanges such as ring joint type and others are also available. Y-strainers can be made to U.S. Navy flange dimensions, that are different from commercial standards.
In addition to flanged and threaded connections, carbon and stainless steel Y-strainers are also available with socket weld and butt weld end connections. These are used mostly for higher pressure applications, 600 psi and above.  Socket weld strainers above the 3 inch size are not often encountered.