PIG AND METHOD FOR CLEANING TUBES

• US 20010047811A1
• Filed: 09/24/1998
• Published: 12/06/2001
• Est. Priority Date: 09/24/1998
• Status: Active Grant

• Current Assignee: Orlande Sivacoe
• Original Assignee: On Streams Technologies Inc.
• Inventors: SIVACOE, ORLANDE
• Granted Patent: US 6,569,255 B2
• Time in Patent Office: Days
• US Class Current: 134/8
• CPC Class Codes: B08B 9/0553 Cylindrically shaped pigs
• CPC Class Codes: F28D 2021/0059 for petrochemical plants
• CPC Class Codes: F28G 1/12 Fluid-propelled scrapers, bullets, or like solid bodies

Abstract

A method of cleaning tubing in an operating heater, in which the tubing has an inlet and an outlet. While the heater is in operation, a hollow, metallic and/or tubular mesh pig is run through the tubing from the inlet to the outlet. Cleaning should be done before contaminant has hardened. An improved pipe pig, preferably hollow, metallic and/or made from tubular mesh, has scraping edges made from longitudinal edges of a wire. The tubular mesh may be a knit, weave or may be knotted. The pig is preferably radially expandable up to twice its fully compressed radius, and may have an expander to force it radially outward. The pipe pig is preferably made of a resilient wire having a polygonal cross-section.

Claims

1. A pig for cleaning tubes, comprising:

a hollow body having a circular cross-section in at least one plane perpendicular to an axis of the body, the body having an outer periphery; and

scraping edges forming the outer periphery of the body, wherein the scraping edges are longitudinal edges of a wire.

2. The pig of

claim 1

in which the body is formed of a helical wire and the scraping edges are edges of the helical wire.

3. The pig of

claim 1

in which the body is formed of a tubular mesh made of wire and the scraping edges are edges of the wire making the tubular mesh.

4. The pig of

claim 3

in which the tubular mesh is radially expandable.

5. The pig of

claim 4

further comprising an expander biased against the tubular mesh for urging the tubular mesh radially outward.

6. The pig of

claim 5

in which the expander is a spring.

7. The pig of

claim 6

in which the expander is a helical spring disposed inside the tubular mesh.

20. The pig of

claim 1

in which the scraping edges lie in planes which are substantially perpendicular to the axis of the body.

8. A pig for cleaning tubes, comprising:

a body having a circular cross-section in at least one plane perpendicular to an axis of the body, the body having an outer periphery;

scraping edges forming the outer periphery of the body, wherein the scraping edges are longitudinal edges of a tubular mesh made of wire.

9. The pig of

claim 8

in which the tubular mesh is radially expandable.

10. The pig of

claim 9

further comprising an expander biased against the tubular mesh for urging the tubular mesh radially outward.

11. The pig of

claim 10

in which the expander is a spring.

12. The pig of

claim 11

in which the expander is a helical spring disposed inside the tubular mesh.

13. The pig of

claim 9

in which the tubular mesh is radially expandable from a first radius to at least twice the first radius.

14. The pig of

claim 8

in which the tubular mesh is a knit.

15. The pig of

claim 8

in which the tubular mesh is a weave.

16. A pig for cleaning tubes, comprising:

a body made entirely from metal and having a circular cross-section in at least one plane perpendicular to an axis of the body, the body having an outer periphery; and

scraping edges forming the outer periphery of the body, wherein the scraping edges are longitudinal edges of a wire.

17. The pig of

claim 16

in which the pig is entirely made of metallic wire.

18. The pig of

claim 17

in which the metallic wire has a polygonal cross-section.

19. The pig of

claim 18

in which the wire has a square cross-section.

21. The pig of

claim 16

in which the body is radially expandable.

22. The pig of

claim 21

in which the body is radially expandable from a first radius to at least twice the first radius.

23. A pig for cleaning tubes, comprising:

a hollow metallic body having a circular cross-section in at least one plane perpendicular to an axis of the body, the body having an outer periphery; and

scraping elements formed on the outer periphery of the body for cleaning tubing, the scraping elements having scraping edges.

24. The pig of

claim 23

in which the scraping edges are edges of a wire.

25. The pig of

claim 24

in which the scraping edges are longitudinal edges of a wire.

28. The method of

claim 25

further comprising:

returning the tubular mesh pig to the inlet along return tubing, in parallel connection to the heater tubing.

29. The method of

claim 28

in which the method is carried out while the heater is in operation.

30. The method of

claim 29

in which the pig is run through the tubing after contaminant has formed on the inside of the tubing but before the contaminant has hardened.

31. The method of

claim 28

further comprising, before the tubular mesh pig is run through the tubing while the heater is in operation, thoroughly cleaning the tubing with a pig having a robust scraping action.

32. The method of

claim 31

in which the pig with a robust scraping action is a polymer pig with metallic scraping elements embedded in the polymer pig.

26. A method of cleaning tubing, in which the tubing has an inlet and an outlet, the method comprising the step of running a tubular mesh pig having a scraping action through the tubing from the inlet to the outlet, wherein the scraping action is caused by longitudinal edges of one or more wires on the outer periphery of the pig.

27. The method of

claim 26

in which the tubing is tubing in a heater and the step of running the pig through the tubing is carried out repeatedly.

33. A method of cleaning tubing, in which the tubing has an inlet and an outlet, the method comprising the step of running a pig having a scraping action through the tubing from the inlet to the outlet while the heater is in operation, wherein the scraping action is caused by longitudinal edges of one or more wires on the outer periphery of the pig.

34. The method of

claim 33

in which the pig is run through the tubing after contaminant has formed on the inside of the tubing but before the contaminant has hardened.

35. The method of

claim 33

comprising repeating the step of running the pig through the tubing after contaminant has formed on the inside of the tubing but before the contaminant has hardened.

36. The method of

claim 33

further comprising, before the pig is run through the tubing while the heater is in operation, thoroughly cleaning the tubing with a pig having a robust scraping action.

37. The method of

claim 36

in which the pig with a robust scraping action is a polymer pig with metallic scraping elements embedded in the polymer pig.

38. A method of cleaning tubing with a pig, in which the tubing has an inlet and an outlet, and the tubing has a first section with a first diameter and a second section with a second diameter and the pig is variably expandable for cleaning both the first and second sections, the method comprising the step of running a pig having a scraping action through the tubing from the inlet to the outlet through the first and second sections, wherein the scraping action is caused by longitudinal edges of one or more wires on the outer periphery of the pig.

39. The method of

claim 38

in which the method is carried out while the heater is in operation.

40. The method of

claim 39

in which the pig is run through the tubing after contaminant has formed on the inside of the tubing but before the contaminant has hardened.

41. The method of

claim 39

further comprising, before the pig is run through the tubing while the heater is in operation, thoroughly cleaning the tubing with a pig having a robust scraping action.

42. The method of

claim 41

in which the pig with a robust scraping action is a polymer pig with metallic scraping elements embedded in the polymer pig.