Fittings must also be compatible with the material of the vessel (tube, pipe, or hose) they are attached to. Often this means that the fitting material matches the material used for the vessel, ...

Wrench-tightened—Wrench-tightened fittings must be tightened with a wrench. They can be used for applications such as swaging (fixing a fitting to a tube permanently). Ferrules are often manufactured ...