Small animals tend to live shorter lives than larger animals. There are a few theories as to why that is, but the one I believe is most popular is: small animals tend to live shorter lives anyway (because of threats from predators), so there are fewer opportunities to evolve to be long-lived.
The American National Standards Institute (ANSI) Class 150 is a system of dimensional standards for weld neck, threaded, slip-on, lap joint, socket weld and blind flanges. Dimensions for facing, bolts and studs are also included in ANSI Class 150. ANSI Class 150 establishes measures for pipe sizes.
How well do you know your pipe flanges? Remember that flanges come in a variety of shapes and sizes to suit different applications. A flange is usually in the shape of a disc and is used to connect two tubes together or to connect a pipe to a valve, tee, choke or other component. Providing support and strength, two flanges are typically attached to pipe ends with a gasket in between.