Fluid flow control device having a seat ring retainer

A method for assembling a control valve having a body defining an inlet, an outlet, and a fluid flow path extending from the inlet to the outlet, a valve seat ring defining an orifice, a throttling element configured to engage the valve seat ring to prevent fluid flow through the orifice, and a valve seat ring retainer, the method comprising:

• providing the valve body with internal threads;
• providing the valve seat ring with an outwardly extending annular flange;
• providing the valve seat retainer with an inwardly extending annular ring and external threads sized to engage the internal threads of the valve body, a plurality of threaded holes extending through the inwardly extending annular ring;
• inserting the valve seat ring into a bore of the valve body along the fluid flow path;
• threading the retainer into the valve body and positioning the inwardly extending annular ring over the outwardly extending annular flange of the valve seat ring such that a lowermost surface of the retainer is spaced apart from the valve seat ring and does not contact another element of the control valve;
• and
• screwing a plurality of bolts, each extending entirely through a corresponding one of the threaded holes in the inwardly extending annular ring of the retainer and into engagement with the valve seat ring to force a surface of the valve seat ring into engagement with a corresponding surface of the valve body to form a seal between the surface of the valve seat ring and the corresponding surface of the valve body to prevent flow past the valve seat ring external to the valve seat ring orifice.

A control valve comprising:

• a body defining an inlet, an outlet, and a fluid flow path extending from the inlet to the outlet;
• a valve seat ring disposed within the valve body and defining an orifice, the valve seat ring having a radially outwardly extending flange;
• a valve cage disposed within the valve body, the valve cage having a lower portion engaging the valve seat ring and an interior bore, the valve cage having a plurality of fluid flow passages;
• a fluid flow path defined at least in part by the orifice and the fluid flow passages;
• a throttling element sized to fit in the interior bore of the valve cage and configured to engage the valve seat ring to prevent fluid flow through the orifice when the throttling element is disposed in a closed position closing the fluid flow path, and movable between an open position opening the fluid flow path and the closed position;
• and
• a threaded retainer ring threadably secured to the valve body radially outward of the valve seat ring and radially outward of the lower portion of the valve cage, the retainer ring including an inwardly extending annular ring having a plurality of spaced threaded holes;
• and
• a bolt disposed in each of the threaded holes, each bolt extending entirely through the respective threaded hole and positioned to apply a compressive force directly against the radially outwardly extending flange of the valve seat ring and forcing the valve seat ring away from the retainer ring.