Shutoff seal assemblies and related valve assemblies and methods

1. A valve assembly, comprising:

a valve body including a seat-retainer chamber;

a floating seat ring disposed in the seat-retainer chamber, the floating seat ring configured to contact a first portion of a plug head at a single annular location prior to a second portion of the plug head contacting a valve seat during a closing stroke of the plug head, the floating seat ring being axially spaced from the valve seat and configured to move axially toward the valve seat after being contacted by the plug head at an end of the closing stroke;

a sleeve at least partially defining an inner sidewall in the seat-retainer chamber;

a static seal located radially between the floating seat ring and the inner sidewall defined by the sleeve; and

a seat retainer retaining the floating seat ring in the seat-retainer chamber, wherein the static seal is located axially between the floating seat ring and the seat retainer.

2. The valve assembly of claim 1 , wherein the floating seat ring comprises an annular extension extending axially along the static seal.

3. The valve assembly of claim 2 , wherein the annular extension of the floating seat ring partially encloses the static seal in a cavity defined between the sleeve, the seat retainer, and the floating seat ring.

4. The valve assembly of claim 3 , wherein the floating seat ring is bordered by at least a portion of the sleeve and at least a portion of the seat retainer.

5. The valve assembly of claim 2 , wherein the annular extension of the floating seat ring overlaps with at least a portion of the seat retainer along a radial direction.

6. The valve assembly of claim 1 , wherein the static seal is disposed in a cavity located radially between an axially extending portion of the floating seat ring and the sleeve and located longitudinally between the floating seat ring and the seat retainer.

7. The valve assembly of claim 1 , wherein the static seal comprises a coil spring.

8. A sealing assembly for use with a valve assembly, comprising:

a floating seat ring comprising an annular extension and configured to be disposed and move within a seat-retainer chamber of the valve assembly, the floating seat ring configured to contact a first portion of a plug head of the valve assembly at a single annular location prior to a second portion of the plug head contacting a valve seat during a closing stroke of the plug head;

a seat retainer configured to retain the floating seat ring in the seat-retainer chamber; and

a static seal located radially adjacent to the annular extension of the floating seat ring and axially between a body portion of the floating seat ring and the seat retainer, the static seal configured to bias the floating seat ring in an initial position spaced from the seat retainer.

9. The sealing assembly of claim 8 , further comprising a sleeve configured to at least partially radially encompass the floating seat ring and define an inner sidewall in the seat-retainer chamber.

10. The sealing assembly of claim 9 , wherein the static seal is contained within a chamber defined by the floating seat ring, the seat retainer, and the sleeve.

11. The sealing assembly of claim 10 , wherein the annular extension of the floating seat ring overlaps with at least a portion of the seat retainer along a radial direction of the sealing assembly.

12. The sealing assembly of claim 11 , wherein the seat retainer comprises an annular notch configured to receive a portion of the annular extension of the floating seat ring.

13. The sealing assembly of claim 10 , wherein a majority of the static seal is contained within a chamber defined between the floating seat ring and the seat retainer.

14. The sealing assembly of claim 10 , wherein the floating seat ring is configured to move in substantially only in an axial direction after being contacted by the plug head during the closing stroke of the plug head.

15. A method of forming a seal in a valve assembly, comprising:

disposing a movable floating seat ring within a seat-retainer chamber of the valve assembly;

biasing the floating seat ring in an initial position with a static seal;

defining a seal with a first portion of a plug head of the valve assembly with the floating seat ring at a single annular location prior to a second portion of the plug head contacting a valve seat during a closing stroke of the plug head;

retaining the floating seat ring in the seat-retainer chamber with a seat retainer; and

compressing Hail the static seal with the floating seat ring during the closing stroke of the plug head, the static seal located axially between the floating seat ring and the seat retainer.

16. The method of claim 15 , further comprising radially enclosing at least a portion of the static seal with an annular extension of the floating seat ring.

17. The method of claim 16 , further comprising radially overlapping a portion of the annular extension of the floating seat ring along the seat retainer.

18. The method of claim 15 , further comprising moving the floating seat ring in an axial direction while at least a portion of the static seal remains fixed in the axial direction.

19. The method of claim 15 , further comprising radially encompassing the static seal and the floating seat ring with a sleeve.

20. The method of claim 19 , further comprising enclosing the static seal with the floating seat ring, the seat retainer, and the sleeve.