A typical circulator pump has flanged inlet and outlet connections, requiring the user to purchase and install a flange kit with outlets corresponding to the type and size of the piping used. These flanges are available in cast iron (threaded), stainless steel (threaded) and bronze (threaded and sweat) options and come complete with nut and bolts to make a proper connection to the pump. The ANSI Class rating of a flange is defined as the maximum amount of pressure that the flange can withstand at increasing temperatures. There are seven primary pressure classes for flanges. They are 150, 300, 400, 600, 900, 1500, and 2500.