My girlfriends boyfriend had a bench warrant issued for him (state of washington-kitsap county) but I couldn't tell what it was for--(he has had recent dom violence charges & also broke a restraining order--) then aprox 2 months later I see there's another bench warrant issued with a different case# but I still can't tell what its for--my girlfriend thinks the be warrant expires every 30 days--? Would they give it a new case# every time? I can see all his unsealed past criminal records and the case#'s on the warrants don't match any of those...

A bench warrant is normally for failure to appear. So most likely he was suppose to appear for a crime and did not appear.

No a bench warrant never expires on its own. If it is for some minor taffic issues, sometimes the local judges clear out old ones ( over a few years)
But no it will not expire in 30 days. So he can expect to be arrested 20 years from now on it, if it is not cleared up before then

I live in Oregon. I had a bench warrant for failure to appear in 2009. I had been real cautious for police. A police/ swat guy started at my job I got to know him pretty well. Got him to run my name the failure to appear is still their but no warrant. Not sure how it went away but it's gone.