Abstract: A removable valve seat has a peripheral annular flange retained between an annular shoulder in a flow passage and a pair of retainer pins slidably received in bores defined in the valve body. The pins are not threadedly or otherwise engaged in the bores but instead extend beyond the bore termini toward the valve access opening and are prevented from substantial axial displacement by a collar projecting into the access opening from a bonnet. The collar also precludes clapper mounting pins from being dislodged from open hanger recesses disposed in a hanger surface. Removal of the valve seat and other components are readily effected via the access opening by removing the cover, lifting the clapper out from the hanger recess, sliding the retainer pins out from their respective bores and then withdrawing the valve seat out of its flow passage.