Swivel joint or Ball and socket joint I believe its a compression type fitting. Similar to a compression coupling fitting for 4" cast iron. Matt Looked kind of like this w/o the clamps? Click to Enlarge 27.01 KB From Piping Handbook, 7th Edition For river crossings, submarine lines, or other places where great flexibility is necessary, ductile cast-iron pipe can be obtained with ball-and-socket joints of the mechanical- gland types, as shown in Fig. A2.31. Provision is made for longitudinal expansion and contraction, and a positive stop against disengagement of the joint is a feature of the design. As much as 15o angular deflection can be accommodated without leakage. This pipe is heavy enough to remain underwater where laid without requiring river clamps or anchorage devices. Click to Enlarge 27.01 KB