Yes, STRIPE is a Scrabble word!

Letter values in Scrabble US: S 1, T 1, R 1, I 1, P 3, E 1.

Is it a valid word?

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

an adornment consisting of a strip of a contrasting color or material
a piece of braid, usually on the sleeve, indicating military rank or length of service
V-shaped sleeve badge indicating military rank and service
a kind or category
a narrow marking of a different color or texture from the background

Also: grade insignia.