In many hydraulic systems, inflexible or rigid pipes or tubes are used to transfer energy-generating liquid between different components to form a complete hydraulic circuit. Pipes and tubes can be rigid in order to bridge small amounts of space in a controlled manner. For instance, in a hydraulic circuit contained within a small casing, there is no extra room for piping, so the connections must be rigid and contained within the casing. Some hydraulic circuits have much more liberal space accommodations or even require connection flexibility to facilitate faster replacement or range of motion operations. For example, many construction machines have external, flexible hydraulic hose connections so the tools are free to move.
A number of standards exist for hydraulic hose production and use. Standards govern industry connection specifications and hose material, as well as guide installation operations.