Yes, SIEVING is a Scrabble word!

Letter values in Scrabble US: S 1, I 1, E 1, V 4, I 1, N 1, G 2.

Is it a valid word?

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

examine in order to test suitability
check and sort carefully
separate by passing through a sieve or other straining device to separate out coarser elements
distinguish and separate out

Also: screen out.