Add a Circle and set the desired vertices number. Extrude a circle upward (E,Z) to make a cylinder. Add the edge loops in the middle of it (Ctrl+R), then scale them to make the cylinder look more like a barrel. Add the edge loops to the cylinder's upper and lower edges.
Enable the edge selection (Ctrl+Tab-->Edge). Select one vertical edge and press Shift+G-->Select Similiar-->Face Angles. Now press Ctrl+B and change the Segments number to 3. Then press Ctrl+- to reduce the selection and delete remained faces.
Add the Solidify (increase the Thickness value) and Subsurf (increase the subdivisions level) modifiers