Applications of Expansion and Contraction

Expansion and contraction have desirable and destructive effects. The following are examples of precautions usually taken to avoid or minimize the damaging effects.

(a)Steel bridges:Some bridges are supported on rollers to enable them move freely as they expand or contract. In other designs, expansion gaps are provided to absorb the increase in length during hot seasons.

(b)Railway lines: Expansion gaps are provided between rails. Without these gaps, bending easily occurs during expansion and this has been a major cause of train accidents in the past. The modern ways of preventing bending of rails due to expansion, however, involve overlapping and welding of rails.

(c)Steam pipe: A steam pipe is looped at some points along its length to allow for expansion and contraction. This prevents the pipe from bursting due to expansion.