If you beat on your metal bellows Expansion Joints with a sledge hammer in order to try and knock the material inside loose, the metal bellows become ineffective and may as well not be there. Also, this particular metal bellows has a flow-liner (or shield) inside, so the person who hit it probably didn't even unplug the pipe like they'd hoped to.

If you beat on your metal bellows Expansion Joints with a sledge hammer in order to try and knock the material inside loose, the metal bellows become ineffective and may as well not be there. Also, this particular metal bellows has a flow-liner (or shield) inside, so the person who hit it probably didn’t even unplug the pipe like they’d hoped to.