Hard to tell by pic but the best design is where the pipes from the tank go into one section then water is forced to go through the filter socks to enter in the next section. Like Masterbuilder said that allows you to remove a dirty sock with out having to deal with a pipe inside the sock.
And yes there is an easy way to "un weld" the seam its called a saw or dremel....you are't going to just just "un weld" the seam.