The bean pot/plumber's lead melting pot is for three inch cast iron pipe. A retired master plumber friend of mine told me many years ago that the size of the pot, indicated in this case by the number 3, is in direct proportion to the amount of lead required to fill the cavity between the walls of the cast iron fitting and the cast iron pipe, poured in on top of the oakum that is packed in very tightly. The oakum is an oil impregnated ropelike fiber that insures that the connection is waterproof. The melted lead solidifies around the pipe to provide a very rigid joint.
