Which method is commonly used to provide expansion in pipelines?

The commonly used method for providing expansion in pipelines is through expansion bends. Expansion bends are specifically designed to accommodate thermal expansion and contraction that occurs within a pipeline due to temperature variations. As the temperature of the fluid in the pipeline changes, the materials of the pipeline also expand or contract, which can create stress in the system.

By incorporating expansion bends, the pipeline is able to flex and adapt to these changes without causing damage or misalignment. This flexibility helps maintain the integrity and safety of the pipeline, preventing leaks or failures that might occur if the thermal expansions were unable to be accommodated.

In contrast, options like expansion tanks and expansion joints serve different purposes; expansion tanks are typically used in closed-loop systems to balance pressure changes, while expansion joints are flexible fittings that allow for movement but do not necessarily take the shape of a bend. Rigid supports, on the other hand, stabilize the pipeline but do not allow for the necessary flexibility to handle thermal expansion effectively. Thus, expansion bends are the most direct and effective method to manage expansions in pipelines.