For connecting cast iron pipes that are to be embedded in the ground, a common joint used is the "hub and spigot" joint. This joint is also known as the "bell and spigot" joint.
In a hub and spigot joint, one end of the cast iron pipe has a bell-shaped (or hub) opening, while the other end has a corresponding spigot (or plain) end. When joining two cast iron pipes together, the spigot end of one pipe is inserted into the bell end of the other pipe, creating a sealed connection. The joint is typically sealed using a flexible material like rubber or neoprene gaskets and sometimes also using cement or grout to ensure a water-tight fit.
The hub and spigot joint is widely used in underground sewer and drainage systems where the pipes need to be connected securely to withstand the pressure and prevent leaks.