Method and device for applying protective sheeting of polymer material to a pipeline

Abstract

A method of applying protective sheeting of polymer material to a pipeline extending along a longitudinal axis and having a cutback bounded at opposite axial ends by two end portions of respective protective coatings of polymer material, the method including directly heating the free faces of the end portions; extruding and simultaneously winding about the pipeline a protective sheeting wide enough to cover the cutback and the end portions; and compressing the protective sheeting against the pipeline, the end portions included.

Claims

1. A pipeline protective sheeting application device comprising: a carriage rotatable about a pipeline extending along a longitudinal axis and including a cutback bounded at opposite axial ends by two end portions of respective protective coatings of a polymer material; an extrusion die mounted on the carriage, wherein in use, the extrusion die simultaneously winds about the pipeline and extrudes a protective sheeting of polymer material wide enough to cover the cutback and the end portions; a heat treating unit mounted on the carriage and including at least two heaters, wherein the at least two heaters are located between the extrusion die and the pipeline, and in use, said heat treating unit directs and confines heat onto the end portions to directly heat free faces of the end portions; and a roller configured to compress the protective sheeting against the pipeline including the end portions.

2. The pipeline protective sheeting application device of claim 1, wherein in use, the at least two heaters soften, by directly heating, a surface layer of each end portion before the protective sheeting, not completely hardened, is applied onto the softened surface layers.

3. The pipeline protective sheeting application device of claim 2, wherein in use, the at least two heaters direct and confine at least one of hot air, radiation and a flame onto the free faces of the end portions.

4. The pipeline protective sheeting application device of claim 1, wherein the heat treating unit includes at least one heat source selected from: an infrared lamp, an electric resistor, a gas emitter, and a gas burner.

5. The pipeline protective sheeting application device of claim 4, wherein the heat treating unit includes: a fan which, in use, generates a hot airflow which intercepts the at least one heat source; and a heater which, in use, directs and confines the hot airflow onto the free faces of the end portions.

6. The pipeline protective sheeting application device of claim 4, wherein the heat treating unit includes at least two heat sources which, operation, generate and direct flames onto respective end portions.

7. The pipeline protective sheeting application device of claim 4, wherein the heat treating unit includes at least two heat sources which, in use, generate and direct an electromagnetic radiation onto the end portions.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Certain embodiments of the present disclosure will be described by way of example with reference to the attached drawings, in which:

(2) FIG. 1 shows a partly exploded, partly sectioned schematic, with parts removed for clarity, of one step in the method according to the present disclosure;

(3) FIG. 2 shows a larger-scale, partly sectioned, lateral elevation, with parts removed for clarity, of the device configured to apply protective sheeting to a pipeline in accordance with a first embodiment of the present disclosure;

(4) FIG. 3 shows a larger-scale, partly sectioned, lateral elevation, with parts removed for clarity, of the device configured to apply protective sheeting to a pipeline in accordance with a second embodiment of the present disclosure; and

(5) FIG. 4 shows a larger-scale, partly sectioned, lateral elevation, with parts removed for clarity, of the device configured to apply protective sheeting to a pipeline in accordance with a third embodiment of the present disclosure.

DETAILED DESCRIPTION

(6) Referring now to the example embodiments of the present disclosure illustrated in FIGS. 1 to 4, number 1 in FIG. 1 indicates a pipeline composed of two pipes 2 joined by a weld, of which is shown an annular weld bead 3. Each pipe 2 comprises a metal cylinder 4; and a coating 5 of polymer material, normally polyethylene or polypropylene, for corrosion-proofing metal cylinder 4.

(7) Each pipe 2 has two opposite free ends 6 (only one shown in FIG. 1) with no coatings 5. Each coating 5 has a bevel 7 at each free end 6. Two pipes 2 welded together form a cutback 8, which extends along a longitudinal axis A1, between two successive bevels 7.

(8) In addition to welding metal cylinders 4, joining pipes 2 also comprises coating cutback 8. This comprises applying protective sheeting 9 of polymer material to pipeline 1, at cutback 8.

(9) In the example shown, protective sheeting 9 is configured to wind around cutback 8, is wider than cutback 8 (measured along longitudinal axis A1) so as to overlap coatings 5 and relative bevels 7 of the two joined pipes 2, and is long enough to wind completely around the perimeter of cutback 8. In other words, protective sheeting 9 is superimposed on two end portions 10 of respective coatings 5. Each end portion 10 comprises a bevel 7 and a cylindrical part of coating 5. In certain embodiments, the amount by which protective sheeting 9 overlaps the two pre-existing coatings 5 ranges between 50 and 100 mm measured parallel to longitudinal axis A1, which means the width of each end portion ranges between 50 and 100 mm.

(10) In certain embodiments, protective sheeting 9 is extruded and wound simultaneously about pipeline 1, and is compressed onto pipeline 1 by a roller 11.

(11) The newly extruded protective sheeting 9 is soft, in the sense that the polymer material has first been plastified to extrude the protective sheeting, and has not yet hardened. So the protective sheeting is highly flexible and adapts to the irregular shape of the part of pipeline 1 to which the protective sheeting is applied. Roller 11 ensures protective sheeting 9 adheres to the surface of pipeline 1 to which the protective sheeting is applied, and prevents the formation of air bubbles, without altering the thickness of protective sheeting 9.

(12) Roller 11 rotates idly, or is powered to rotate, about an axis of rotation A2, and is pushed onto pipeline 1 by a supporting mechanism 12, of which only two supporting arms 13 are shown in FIG. 1.

(13) Roller 11 varies in elasticity along axis A2, and more specifically is of greater elasticity at the ends than at the center. At the center, roller 11 has a groove 14 configured to align with annular weld bead 3.

(14) Number 15 in FIG. 1 indicates a number or quantity of heaters which, in the example shown, define respective hot-air conductor outlets facing and positioned a short distance from end portions 10.

(15) The main purpose of each heater 15 is to heat, and soften a thin surface layer of the free surface of a respective end portion 10.

(16) More specifically, concentrating heat on the free faces of end portions 10 softens the polymer material of coatings 5 along thin surface layers of respective end portions 10, so as to seal end portions 10 to protective sheeting 9, which is wound around pipeline 1 before protective sheeting is completely hardened.

(17) Number 16 in FIG. 2 indicates as a whole a device configured to apply protective sheeting 9 to pipeline 1.

(18) Device 16 comprises a carriage 17 which runs along an annular path around pipeline 1; an extrusion die 18 configured to extrude protective sheeting 9; roller 11 configured to compress protective sheeting 9 onto pipeline 1; and a heat treating unit 19 configured to effectively seal end portions 10 to protective sheeting 9.

(19) Extrusion die 18 comprises an extrusion outlet 20 from which protective sheeting 9 comes out, and is mounted on carriage 17 to pivot about an axis A3 to enable actuators (not shown in the drawings) to adjust the tilt of extrusion die 18 and the distance between extrusion outlet 20 and pipeline 1.

(20) Roller 11 is connected to carriage 17 by arms 13 and is adjustable by actuators (not shown).

(21) Heat treating unit 19 is mounted on carriage 17, such as pivotably mounted about an axis A4 and adjustably by actuators (not shown in the drawings), and comprises a heat source 21, two fans 22 (only one shown in FIG. 2), heaters 15 (only one shown in FIG. 2), and conduits 23 (only one shown in FIG. 2) configured to connect heat source 21, fans 22, and heaters 15. Heat source 21 is selected on the basis of energy demand and other contingencies. The types of heat sources 21 comprise: infrared lamps, gas burners, and electric resistors.

(22) In actual use, carriage 17 is run in direction D1 in FIG. 2. And, as carriage 17 runs along, heat treating unit 19 heats end portions 10, substantially by convection, to soften surface layers of end portions 10; extrusion die 18 extrudes protective sheeting 9 close to pipeline 1, so that protective sheeting 9 is deposited, still partly softened, onto pipeline 1, and in particular onto end portions 10; and roller 11 compresses protective sheeting 9 onto pipeline 1, and in particular onto end portions 10, so that surface layers of the still-soft protective sheeting 9 adhere firmly to the soft surface layers of end portions 10.

(23) Once the whole length of protective sheeting 9 is wound about pipeline 1, extrusion is stopped, extrusion die 18 and heaters 15 may be withdrawn from pipeline 1, but roller 11 continues to exert pressure on pipeline 1.

(24) Next, carriage 17 is run in the opposite direction to direction D1 to perform a rolling operation (i.e., with roller 11 still exerting pressure to compress protective sheeting 9 as protective sheeting hardens).

(25) In the example shown, heaters 15 concentrate the hot airflow within circumscribed areas.

(26) In the FIG. 3 embodiment, the heat treating unit 24 comprises two heaters 25 (only one shown in FIG. 3); and two heat sources 26 (only one shown in FIG. 3) inside respective heaters 25 which, in the example shown, are outlets facing end portions 10 and configured to house respective heat sources 26.

(27) In the example shown, each heat source 26 is defined by a gas burner configured to generate and direct a flame onto a respective end portion 10. More specifically, each heat source 26in the example shown, each burnercomprises an arc-shaped diffuser 27 which, in use, is positioned facing and close to a respective end portion 10.

(28) Heat treating unit 24 also comprises a flame sensor 28 and an ignition device 29, both located inside heater 25.

(29) Heat treating unit 24 comprises a fan 30; a mixer valve 31; a conduit 32 configured to conduct air and the air/gas mixture to diffuser 27; and a conduit 33 configured to feed gas to mixer valve 31.

(30) In actual use, heat treating unit 24 provides for igniting the heat source 26 and moving carriage 17. The flame is evenly distributed along diffuser 27, sweeps the outer face of a respective end portion 10, and softens a thin surface layer of end portion 10 to join end portion more effectively to protective sheeting 9.

(31) Number 34 in FIG. 4 indicates as a whole a heat treating unit comprising a heater 35; and a radiant heat source 36, (e.g., infrared lamps, electric resistors, or a gas emitter).

(32) Heat source 36 is housed inside heater 35, which serves to concentrate radiation along a respective end portion 10.

(33) Clearly, changes may be made to the embodiments of the present disclosure described with reference to the attached drawings without, however, departing from the protective scope of the accompanying Claims. For example, the free faces of the end portions may be heated directly by conduction, using heated rollers configured to roll along the end portions, or other heated elements configured to slide along the end portions. Accordingly, various changes and modifications to the presently disclosed embodiments will be apparent to those skilled in the art. Such changes and modifications can be made without departing from the spirit and scope of the present subject matter and without diminishing its intended advantages. It is therefore intended that such changes and modifications be covered by the appended claims.