As a general rule, 2-piece ball valves are not intended to be disassembled. 3-piece, ball valves, on the other hand, ARE designed to be disassembled without having to remove them from the piping system. All that said, I circulate a very hot solution of PBW and Oxy Clean for a minimum of 1 hour after each brew and it must be working. After my home brewery was up and running for one year (about 14 brews) I took apart my pump and a selection of fittings. I was amazed how clean they were.
Also, before each brew, I circulate a hot solution of Star-San through my pump, plate cooler and cold side. All good, never any issues.