U-bend 
noun
A section of a pipe, in particular of a waste pipe, shaped like a U.It can't go down to pass through a U-bend in the hose....
- The microelectrodes were calibrated as described previously using a modified glass funnel that incorporated a U-bend.
- It's a clever and convincing argument but with one immovable blockage lodged firmly in the U-bend, water provided by the local utility is cleansed and service provider connectivity is not.