buroak,
I have no idea what the "risks" would be. There's a persistent myth that briar is highly porous and absorbs moisture. :nana: It does, I suppose, but very very slowly. I've seen pipes cut in half and the tars of well-smoked pipes barely got more than half a millimeter into the wood. I've done the same with an old pipe of mine and the briar inside was clean as a whistle. Anyhow, I guess if there were lots of tars or cake in either the bowl or the shank, the water could cause those to expand in a bad way. And yet, the cake and shank are going to get wet anytime you actually smoke the pipe. I would say the real "risk" is that you'd have wet cake in the bowl and damp tars in the shank.
When I clean an estate, unless it's really old and potentially fragile, I pretty much go down to the bare wood, so I don't see any risk there.
In any case, I've literally washed estate bowls in the faucet with warm water and a toothbrush (for the chamber) and you would never guess which pipes I had done that to.
Final thoughts, if the stem is already removed, a really wet shank will expand enough that the stem won't go back in properly without risking breakage. You'll have to let it dry. Otherwise, I've found plain water to be plenty safe.
