Choke for a flow line

1. A choke element for reducing the velocity and pressure of a fluid flow in a flow line, the flow line having an inner diameter, the choke element comprising:

a body having an upstream end, a downstream end, and a sidewall that extends between the upstream end and the downstream end, the sidewall having a diameter that is sized to fit within the inner diameter of the flow line;

a fluid impact face at the upstream end of the body, the fluid impact face having a recessed central portion; and

a flow path in fluid communication between the downstream end and the upstream end of the body, the flow path comprising:

a flow restriction formed by an annular space defined by the sidewall of the body and the inner diameter of the flow line;

one or more radial passages that extend inward from the sidewall of the body at a point downstream of the flow restriction between the sidewall and the inner diameter of the flow line; and

an axial passage that intersects the one or more radial passages and is in fluid communication with the downstream end of the body;

wherein the flow restriction defines a point of greatest restriction of the flow path such that fluid traverses the point of greatest restriction as it flows in an axial direction, and wherein the flow restriction is in direct communication with the inner diameter of the flow line immediately upstream of the fluid impact face.

2. The choke element of claim 1 , wherein the recessed central portion is a conical surface that tapers continuously from the fluid impact face to a recessed apex.

3. The choke element of claim 1 , wherein the radial passages have a common point of intersection within the body.

4. The choke element of claim 1 , wherein the flow area of the axial passage at the downstream end of the body is greater than the flow area of the axial passage at the radial passages, the axial passage being defined by a conical surface that comprises a continuous taper between the one or more radial passages and the downstream end of the body.

5. The choke element of claim 1 , wherein the body comprises a threaded surface toward the downstream end that is sized to engage an inner threaded surface of the flow line.

6. The choke element of claim 1 , wherein the flow path has a flow area that increases progressively from the flow restriction to the downstream end of the body.

7. In combination:

a flow line having a sidewall having inner diameter; and

a choke element installed within the flow line, the choke element comprising:

a body having an upstream end, a downstream end, and a sidewall that extends between the upstream end and the downstream end;

a flow path in fluid communication between the downstream end and the upstream end of the body; and

a fluid impact face at the upstream end of the body, the fluid impact face having a recessed central portion, and the flow path being in direct communication with the inner diameter of the flow line immediately upstream of the fluid impact face;

the flow path comprising:

a flow restriction formed by an annular space defined by the sidewall of the body and the inner diameter of the flow line;

one or more radial passages that extend inward from the sidewall of the body at a point downstream of the flow restriction between the sidewall of the body and the inner diameter of the flow line; and

an axial passage that intersects the one or more radial passages and is in fluid communication with the downstream end of the body;

wherein the flow restriction defines a point of greatest restriction of the flow path such that fluid traverses the point of greatest restriction as it flows in an axial direction, and wherein the flow restriction is in direct communication with the inner diameter of the flow line immediately upstream of the fluid impact face.

8. The combination of claim 7 , wherein the recessed central portion is a concave surface that tapers continuously from the fluid impact face to a recessed apex.

9. The combination of claim 8 , wherein the concave surface is conical.

10. The combination of claim 7 , wherein the radial passages have a common point of intersection within the body.

11. The combination of claim 7 , wherein the flow area of the axial passage at the downstream end of the body is greater than the flow area of the axial passage at the radial passages, the axial passage being defined by a conical surface that comprises a continuous taper between the one or more radial passages and the downstream end of the body.

12. The combination of claim 7 , wherein the body of the choke element comprises an external threaded surface toward the downstream end and the flow line comprises an inner threaded surface of the flow line that engages the external threaded surface of the body.

13. The combination of claim 12 , wherein the internal and external threaded surfaces engages to form a seal.

14. The combination of claim 7 , wherein the flow path has a flow area that increases progressively from the flow restriction to the downstream end of the body.