Brass pipe fittings are used within the plumbing business as a means to connect pipes,either in a straight line or at an angle to each other.They can be used for certain other functions, such as controlling water pressure and preventing water from exiting a pipe's end.They can also be used to regulate the flow of liquid through the pipe system.There are many different types of brass pipe fittings and it's necessary to know which does what if a successful system of pipes is to be constructed.