Yes, LIMBERS is a Scrabble word!

Letter values in Scrabble US: L 1, I 1, M 3, B 3, E 1, R 1, S 1.

Is it a valid word?

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

a channel or gutter on either side of a ship's keelson; carries bilge water into the pump well
a two-wheeled horse-drawn vehicle used to pull a field gun or caisson

Also: limber up.