A system includes an adapter configured to provide an interface between a first fluid conduit and a second fluid conduit. The adapter has an inner wall and an outer wall. The adapter has a first end configured to fit against a first inside wall of the first fluid conduit. The adapter also has a second end configured to fit against a second inside wall of the second fluid conduit. The inner wall of the adapter has a first curvilinear transition from a first inside diameter at a first opening of the first end to an intermediate diameter between the first and second ends. The inner wall of the adapter has a second curvilinear transition from a second inside diameter at a second opening of the second end to the intermediate diameter.