Pipes can dent real easy. If they didn't they'd be too heavy for racing! It's not unusual to see people using old beat up pipes and winning races. Sometimes you can get one nasty knock and they cave in, then you wanna freeze it.
Remember, the more you work metal, the stronger it gets (notice how a ring pull gets tougher before it finally gets too brittle and breaks). So your pipe will probably a bit tougher for the battle scars.