Why is this - thermal expansion?? 10 points?

Q: In a particular hospital, steam at high pressure and at 120 degrees celcius is produced in the boiler house and sent through a steel pipe to a steam steriliser, or autoclave, which is in another building 150m away. Calculate the change in length of the pipe if the temperature varies from 15 degrees celcius when cold to a maximum of 120 degrees celcius.

I HAVE DONE THIS CALCULATION, PLEASE DO NOT DO IT. I ONLY WANT TO SHOW Q.

My question is one following it. It says that pipes that carry steam have horseshoe bends at regular intervals. It asks what would happen if the bends were not included in the design?

My answer would that the change in length would be lower, which is mathmatically correct.

But in the book it says that the pipes would bend or fracture. Why?????

I would think that the pipe shrinks as the heat from the steam escapes. But why would it have horseshoe bends at regular intervals in the first place?

Any help is greatly appreciated. Thanks in advance.