Why are LNG pipes curved?

The contraction of LNG pipeline which carries a condensed gas ,which caused by low temperature during operation, may impact the structure of pipeline, It is necessary to use compensation structure in the LNG pipeline to deal with the contraction of pipeline. This paper use bent pipe to compensate the amount of contraction of subsea LNG cryogenic pipeline. At the bends, the gas expands and thus maintain a constant volume while being carried from onshore to the processing plant.

Source: cedb.asce