They no longer expire (technically) but they can be revoked if there's no action for 12 months.
(read here: http://www.uscis.gov/sites/default/f...form/i-130.pdf )
(Which basically answers everything)
They no longer expire (technically) but they can be revoked if there's no action for 12 months.
(read here: http://www.uscis.gov/sites/default/f...form/i-130.pdf )
(Which basically answers everything)