Pressure-balanced control valves
A valve assembly comprises a valve body comprising a plug chamber. A static seal is disposed adjacent an inner sidewall of the plug chamber, and a plug comprising a plug head is moveably positioned within the plug chamber, the plug head being configured to contact the static seal only when the plug is adjacent to a seat ring. Methods of using a valve and methods of forming a valve assembly are also disclosed.
1. A valve assembly, comprising:
a valve body including a plug chamber;
a static seal disposed adjacent an inner sidewall of the plug chamber; and
a plug slidably positioned within the plug chamber and comprising a plug head configured to contact the static seal only when the plug is adjacent to a seat ring, the static seal located proximate a top portion of the plug head when the plug is adjacent to the seat ring, wherein the static seal is compressed against a conical, radially-outermost surface of the top portion of the plug head when the plug is adjacent to the seat ring; and
a dynamic seal positioned adjacent to the conical, radially-outermost surface of the top portion of the plug head.
2. The valve assembly of claim 1 , wherein the static seal is positioned in an annular groove in the inner sidewall of the plug chamber.
3. The valve assembly of claim 1 , wherein the plug chamber comprises a sleeve structure.
4. The valve assembly of claim 1 , wherein the static seal comprises a double coil helical spring.
5. The valve assembly of claim 1 , wherein the static seal comprises heat treated elgiloy.
6. The valve assembly of claim 1 , wherein the static seal comprises fluoroloy material.
7. The valve assembly of claim 1 , wherein the plug chamber is defined by a pressure-balanced sleeve, a seat retainer, and the seat ring.
8. A method of operating a valve, comprising:
providing a plug head comprising a dynamic seal positioned to contact an outer diameter of the plug head and an inner sidewall of a plug chamber of a valve body to seal a volume therebetween;
positioning the plug head in the plug chamber and in contact with a seat ring and in contact with a static seal, the static seal positioned in the inner sidewall of the plug chamber and proximate a top portion of the plug head when the plug head is in contact with the seat ring, wherein the static seal is compressed against a conical, radially-outermost surface of the top portion of the plug head when the plug head is in contact with the seat ring; and
moving the plug head longitudinally within the plug chamber and out of contact with the seat ring and the static seal.
9. The method of claim 8 , wherein the dynamic seal is positioned adjacent the conical, radially-outermost surface of the top portion of the plug head.
10. The method of claim 8 , wherein the static seal is positioned in an annular groove in the inner sidewall of the plug chamber.
11. The method of claim 8 , wherein the plug chamber comprises a sleeve structure.
12. The method of claim 8 , wherein the static seal comprises a double coil helical spring.
13. The method of claim 8 , wherein the static seal comprises heat treated elgiloy.
14. The method of claim 8 , wherein the static seal comprises fluoroloy material.
15. The method of claim 8 , wherein the plug chamber is defined by a pressure-balanced sleeve, a seat retainer, and the seat ring.
16. A method of forming a valve assembly, comprising:
forming a valve body comprising an inlet, an outlet and a plug chamber;
positioning a dynamic seal adjacent to an outer diameter of a plug head of a plug;
positioning a static seal adjacent an inner sidewall of the plug chamber; and
positioning the plug into the plug chamber, the plug head being configured to contact the static seal only when the plug is positioned at least adjacent a seat ring, a top portion of the plug head located adjacent the static seal when the plug is positioned at least adjacent the seat ring, and the static seal being compressed against a conical, radially-outermost surface of the top portion of the plug head when the plug is positioned at least adjacent the seat ring.
17. The method of claim 16 , wherein the static seal is positioned in an annular groove in the inner sidewall of the plug chamber.
18. The method of claim 16 , wherein the plug chamber comprises a sleeve structure.
19. The method of claim 16 , wherein the static seal comprises a double coil helical spring.
20. The method of claim 16 , wherein the static seal comprises heat treated elgiloy.
21. The method of claim 16 , wherein the static seal comprises fluoroloy material.
22. The method of claim 16 , wherein the plug chamber is defined by a pressure-balanced sleeve, a seat retainer, and the seat ring.