Patent ID: 8261771

Claim:
A check valve assembly, comprising: a body having a central cavity intersected by upstream and downstream flow passages, the flow passages having a common flow passage axis, the upstream passage having a couterbore that defines a downstream facing shoulder; a seat having a central orifice therethrough and secured by a threaded engagement into the upstream flow passage, a downstream side of the seat having a larger diameter than an upstream side of the seat, defining a flange having an upstream facing shoulder that is spaced apart from an upstream wall of the cavity by a gap and an upstream end of the seat abutting the downstream facing shoulder of the body, the upstream side of the seat having a seal that abuts and seals against the downstream facing shoulder of the body; an access bore intersecting the cavity, the access bore having an access bore axis that is transverse to the flow passage axis; a support shoulder formed in the access bore; a holder insertable into the access bore, the holder extending at least partially around the access bore and landed on the support shoulder; and a flapper pivotally secured to the holder and located in the cavity for movement between an open position and a closed position blocking flow through the orifice of the seat.