Flowline flapper valve

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 flow passage having a set of internal threads adjacent the cavity and a downstream facing shoulder upstream from the internal threads;
• a seat having upstream and downstream sides, a central orifice therethrough, a circumference having a set of external threads that engage the internal threads in the upstream flow passage, the upstream side of the seat having a seal and abutting the downstream facing shoulder and the 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;
• an access bore intersecting the cavity, the access bore having an access bore axis that is perpendicular to the flow passage axis;
• a support shoulder formed in the access bore and facing upward, the support shoulder extending at least partly around an inner diameter of the access bore adjacent a junction of the access bore with the cavity;
• a holder insertable into the access bore, the holder being a disk with a central opening in communication with the cavity, the holder extending at least partially around the access bore and being supported on the support shoulder;
• a hinge block on the holder;
• an anti-rotation device in the access bore and on the holder that prevents rotation of the holder;
• and
• a flapper pivotally secured to the hinge block on the holder by a pin and located in the cavity for movement between an open position and a closed position blocking flow through the orifice of the seat.

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 counterbore that defines a downstream facing shoulder;
• the upstream flow passage having a set of internal threads;
• a seat having upstream and downstream sides, a central orifice therethrough, the upstream side a set of external threads that engage the internal threads in the upstream flow passage, and an external flange on the upstream side of the seat that is spaced apart from an upstream wall of the cavity by a gap and the upstream side of the seat having a seal and abutting the downstream facing shoulder of the body;
• an access bore intersecting the cavity, the access bore having an access bore axis that is perpendicular to then passage axis;
• a support shoulder formed around an inner diameter of the access bore, facing upward, and located in a plane perpendicular to the access bore axis;
• a fastener extending through a hole in the support shoulder into engagement with the flange of the seat to prevent the seat from rotation;
• a holder insertable into the access bore, the holder being a disk with a central opening, the holder being supported on the support shoulder;
• at least one hinge block on the holder;
• a straight edge portion extending downward from the support shoulder and engaged by the holder to prevent rotation of the holder;
• and
• a flapper pivotally secured to the at least one hinge block on the holder and a pin, and located in the cavity for movement between an open position and a closed position blocking flow through the orifice of the seat.