Yes, VALVES is a Scrabble word!

Letter values in Scrabble US: V 4, A 1, L 1, V 4, E 1, S 1.

Is it a valid word?

VALVES is a valid word in the official Scrabble dictionary (US), the UK Scrabble Dictionary and Words with Friends (ENABLE).

a structure in a hollow organ (like the heart) with a flap to insure one-way flow of fluid through it
device in a brass wind instrument for varying the length of the air column to alter the pitch of a tone
control consisting of a mechanical device for controlling the flow of a fluid
the entire one-piece shell of a snail and certain other molluscs
one of the paired hinged shells of certain molluscs and of brachiopods