Flexible lance for machining or inspecting a tubesheet of a boiler

Abstract

The invention relates to a flexible lance for machining or inspecting a tubesheet of a boiler, having a first strip made of a flexible, metallic material and a second strip made of a flexible, metallic material, wherein the second strip is arranged on the first strip in the longitudinal direction, and wherein at least the second strip has a shaped portion extending in the longitudinal direction for receiving a supply line for a machining or inspection head arranged at the free end of the flexible lance, and wherein the first strip is connected to the second strip such that an open side of the shaped portion is covered by the first strip so as to form a guide channel, and wherein at least one edge region of the flexible lance, extending in the longitudinal direction, is formed only by the first strip or the second strip.

Claims

1. A flexible lance for machining or inspecting a tubesheet of a boiler, having a first strip comprised of a flexible, metallic material, and a second strip comprised of the flexible, metallic material, wherein the second strip in a longitudinal direction is disposed on the first strip, and wherein at least the second strip is formed so as to comprise a recess, extending in the longitudinal direction, for receiving a supply line for a machining or inspecting head that is disposed on a free end of the flexible lance, and wherein the first strip is connected to the second strip in such a manner that an open side of the recess is covered by the first strip so as to form a guide duct, and wherein at least a peripheral region of the flexible lance, extending in the longitudinal direction, is formed only by the first strip or the second strip, and wherein the first strip and the second strip have dissimilar widths, a width being defined perpendicularly to the longitudinal direction.

2. The flexible lance as claimed in claim 1, wherein the first strip has two mutually opposite flat sides.

3. The flexible lance as claimed in claim 1, wherein the second strip in the longitudinal direction is disposed on the first strip so as to be symmetrical about a central longitudinal axis of the first strip.

4. The flexible lance as claimed in claim 1, further comprising openings disposed in the longitudinal direction in the peripheral region of said flexible lance.

5. The flexible lance as claimed in claim 1, wherein the first strip and the second strip are connected one to another by spot welding at connection locations.

6. The flexible lance as claimed in claim 1, wherein at least the second strip has gaps which are disposed sequentially in the longitudinal direction and extend perpendicularly to the longitudinal direction.

7. The flexible lance as claimed in claim 6, wherein the gaps at least partially extend beyond the recess.

8. The flexible lance as claimed in claim 6, wherein the gaps are configured as slots.

9. The flexible lance as claimed in claim 6, wherein the gaps comprise first gaps which respectively extend on opposite sides of the second strip and completely beyond the recess, and terminate at a spacing short of the periphery of the second strip.

10. The flexible lance as claimed in claim 9, wherein the gaps comprise second gaps which respectively extend from a periphery of the second strip toward the recess.

11. The flexible lance as claimed in claim 10, wherein the first and the second gaps are disposed respectively in an alternating manner in the longitudinal direction.

12. The flexible lance as claimed in claim 10, wherein a peripheral portion of the second strip has a rounded shape and is respectively disposed between two second gaps.

13. The flexible lance as claimed in claim 1, wherein the first strip and the second strip have different flexural strengths.

14. The flexible lance as claimed in claim 1, wherein the first strip and the second strip have different thicknesses.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The invention, also in terms of further features and advantages, will be explained in more detail hereunder by means of the description of exemplary embodiments and with reference to the appended drawings. In each case in a schematic diagram:

(2) FIG. 1 shows a fragment of a flexible lance in a perspective illustration;

(3) FIG. 2 shows a longitudinal view of the first strip of the flexible lance from FIG. 1, prior to said flexible lance being connected, in a longitudinal view;

(4) FIG. 3 shows a longitudinal view of the second strip of the flexible lance from FIG. 1, prior to said flexible lance being connected, in a longitudinal view; and

(5) FIG. 4 shows a schematic illustration of the flexible lance being employed during the machining or inspecting of a tubesheet of a boiler.

DETAILED DESCRIPTION

(6) FIG. 1 shows a flexible lance 2 for machining or inspecting a tubesheet of a boiler. The flexible lance 2 is assembled from a flexible, metallic first strip 4, and from a flexible, metallic second strip 6. The two strips 4, 6 are composed of spring steel, for example chromium nickel steel, and have a thickness, or wall thickness, respectively, of approximately 0.1 to 0.3 mm. The width B.sub.1 of the first strip 4 is approximately 40 mm, the width B.sub.2 of the second strip 6 being approximately 24 mm. The second strip 6 thus has a smaller width than the first strip 4. The second strip 6 in the longitudinal direction L is disposed on the first strip 4 and has a shaped feature 8, or a receptacle for receiving three supply lines 10, respectively, that extends in the longitudinal direction L, said supply lines 10 being connected to a machining or inspecting head (not illustrated in FIG. 1 for reasons of clarity) that is disposed on the free end 12 of the flexible lance 2. The shaped feature 8 has a profile that in the cross-section is U-shaped, and is elongate in the longitudinal direction L of the lance.

(7) The first strip 4 and the second strip 6 have mutually dissimilar flexural strengths. To this end, the first and the second strip 4, 6 can be of dissimilar thicknesses.

(8) The first strip 4 and the second strip 6 are interconnected by spot welding at connection locations 14 which lie in a peripheral portion 34 of the second strip 6 (cf. FIG. 3). The first strip 4 has two mutually opposite flat sides 16. The shaped feature 8 present in the second strip 6 and a flat side 16 of the first strip 4 that faces the second strip 6 therebetween configure a guide duct 18 in which the supply lines 10 are guided. An open side of the shaped feature 8 herein is covered by the first strip 4 such that the guide duct 18 is closed toward all sides, the supply lines 10 thus being protected from damage. The guide duct 18, like the shaped feature 8, extends in the longitudinal direction L of the flexible lance 2.

(9) Since the second strip 6 is of a lesser thickness than the first strip 4, in the case of a centric, or symmetrical, respectively, disposal of the second strip 6 about a central longitudinal axis M of the first strip 4, peripheral regions 20, 22 of the flexible lance 2 that extend in the longitudinal direction are formed only by the first strip 4. Openings 28 for engaging an advancing installation (not explicitly illustrated) are present in the peripheral regions 20, 22

(10) FIG. 2 shows a fragment of a longitudinal view of the first strip 4 of the flexible lance 2 from FIG. 1 prior to the latter being connected, in a longitudinal view. The connection locations 14 are indicated by dashed lines. The flexible lance 2, or the first strip 4, respectively, in the two peripheral regions 20, 22, thus externally, has in each case one row 24, 26 of openings 28 which in the longitudinal direction are disposed sequentially and at an equidistant mutual spacing A. The width of the openings 28 is approximately 2 mm, the length being approximately 2.5 mm. The openings 28 in the longitudinal direction have in each case a mutual spacing A of approximately 5 mm. On account of only the first strip 4 having to have the openings 28 required for advancing, the production is simplified and jamming of the lance 2 with the gear wheels of the advancing installation is reliably prevented in particular in the case of small curvature radii.

(11) A fragment of a longitudinal view of the second strip 6 of the flexible lance 2 from FIG. 1 is illustrated in FIG. 3 in a longitudinal view, prior to said second strip 6 being connected to the first strip 4. The second strip 6 has a shaped feature 8 that in the case of the completed lance 2 is U-shaped, wherein the regions 8 configure the legs of the shaped feature. The second strip 6 has clearances 30, 32 which are disposed sequentially in the longitudinal direction L and which extend perpendicularly to the longitudinal direction L, thus in a transverse direction Q, and so as to be mutually parallel. The clearances 30, 32 in part extend beyond the shaped feature 8, thus are present in a region of the shaped feature 8, or of the guide duct 18 that in part is formed by the shaped feature 8. In other words, the second strip 6, or the shaped feature 8, respectively, is interrupted by clearances which in the present case are slot-shaped. On account thereof, it is avoided that the flexible lance 2 as a result of the shaped feature 8 is rendered too rigid for some applications, curving of the flexible lance 2 up to a curvature radius that is capable of being set by way of the size of the clearances 30, 32, or slots, respectively, being possible. The clearances are typically a few tenths of a centimeter wide and laser cut, and the mutual spacing B of the clearances 30, 32 in the longitudinal direction L is approximately 1 mm.

(12) According to FIG. 3, the second strip 6 has two dissimilarly shaped clearances 30, 32. A first shape of the clearances, hereunder the first clearances 30, is in each case designed so as to be slot-shaped, and extends on both sides and completely beyond the shaped feature 8. The first clearances 30 terminate in each case at a spacing C short of the periphery of the second strip 6. The first shaped features 30 have a length L.sub.1 of approximately 20 mm.

(13) A second shape of the clearances, hereunder referred to as the second clearances 32, extends in each case from a periphery of the second strip 6 to the shaped feature 8 and in part beyond the latter. The second shaped features 32 are likewise slot-shaped and have a length L2 of approximately 10 mm. A peripheral portion 34 of the second strip 6 that is in each case disposed between two second clearances 32 that are adjacent in the longitudinal direction L has a rounded shape.

(14) The first clearances 30 and the second clearances 32 are sequential so as to respectively alternate in the longitudinal direction L, thus being disposed in an alternating order.

(15) The use of the flexible lance 2 for machining or inspecting a tubesheet 50 of a boiler 52 is shown in FIG. 4, wherein only a fragment of the boiler 52 is illustrated, the tubes 54 thereof being illustrated in the cross section. The tubes 54 are disposed on both sides of a tube passage 56 which is accessible from the outside by way of an inspection port 58 in a wall 60 of the boiler 52. A manipulator 62 which in FIG. 4 is indicated only in a schematic manner is introduced into the tube passage 56 and is movable in a reciprocating manner in the direction 58. The manipulator 62 comprises a drive roller 64 by way of which the flexible lance 2 is introduced between the tubes 54. A machining or inspecting head 66 is disposed at the free end 12 of the flexible lance 2. With the aid of the manipulator 62, or of the drive roller 64, respectively, the machining or inspecting head 66 is guided between the tubes 54 to the position to be checked or machined by moving the flexible lance 2 in the direction 70. The flexible lance 2 can be deflected to both sides for machining and inspecting, wherein it is however advantageous for the first strip 4 when deflected to be on the inside, to have two flat sides 16 and thus is largely planar.

(16) TABLE-US-00001 List of reference signs 2 Flexible lance 64 Drive roller 4 First strip 66 Machining or 6 Second strip inspecting head 8 Shaped feature 68 Direction 10 Supply line 70 Direction 12 Free end of the flexible lance B.sub.1 Width of the first strip 14 Connection locations B.sub.2 Width of the second strip 16 Flat side of the first L.sub.1 Length of first shaped strip feature 18 Guide duct L.sub.2 Length of second shaped 20, 22 Peripheral region feature 24, 26 Row L Longitudinal direction 28 Opening A Spacing of openings 28 30, 32 Clearance B Spacing of peripheral 34 Peripheral portion portion 34 C Spacing of clearances 30, 50 Tubesheet 32 52 Boiler M Central longitudinal axis 54 Tube 56 Tube passage 58 Inspection port 60 Wall 62 Manipulator