GB2234570A

GB2234570A - Foamed jacket production

Info

Publication number: GB2234570A
Application number: GB8927400A
Authority: GB
Inventors: Harvey Davies
Original assignee: Individual
Current assignee: Individual
Priority date: 1989-02-14
Filing date: 1989-12-04
Publication date: 1991-02-06
Also published as: GB8927400D0; GB8903259D0

Abstract

Polymeric material is foamed in situ to produce a foamed jacket for a pipeline, for use, for example, in the petrochemical industry. The jacket is formed between a pipeline 1 or 31 and a coaxial sleeve 2 or 32 by injecting foam-forming ingredients into the space between the pipeline 1 or 31 and the sleeve 2 or 32, by means of at least one foaming head 17 or 44 which is driven progressively along the space between the pipeline and the sleeve as the foam-forming ingredients react to form a foam. The foaming head may comprise an annular jig 17 which can be retracted by a spool 12, a manifold 44 mounted externally of the sleeve on a jig 30 provided with a sleeve splitter 42 and welder 51 to allow insertion of the foam or a jig (60, Fig 7 not shown) provided with a guide (80) and welder (66) for applying foam and a wrap-around sleeve (64). <IMAGE>

Description

Foamed Jacket Production The present invention is concerned with the foaming of polymeric material in situ to produce a foamed jacket and particularly, but not exclusively, the production of insulating jacketing for elongate pipelines, for use, for example, in the petrochemical industry..

It is known to produce insulating jacketing by reacting appropriate prepolymers in such a way that a foam is formed in situ in the space between an elongate pipeline (typically of carbon steel) and an outer rigid sleeve (typically of polyethylene or the like). In this known method, the foam jacketing is typically formed in lengths of up to about 12 feet (about 4 metres) by injecting the prepolymers using lances of up to 12 feet in length, and withdrawing the lances as the foam jacket forms. The disadvantages of this method are that the foam jacket can only be formed in discrete lengths and, because the prepolymer materials are highly reactive, there is a danger that they might prematurely react to cause blockage of the respective lance.

We have now devised a method whereby such disadvantages can be at least alleviated.

According to the invention, therefore, there is provided a method of forming a jacket of foamed polymeric material between an elongate rigid body and a coaxial sleeve, which comprises: injecting foam-forming ingredients into the space between said elongate rigid body and said sleeve by means of at least one foaming head which is moved progressively along said space as said foam-forming ingredients react to form a foam.

The or each foaming head is generally provided with separate supplies of foam-forming ingredients (such as a polyol, a polyisocyanate and air when, as is preferred, the foam is a polyurethane), such that the ingredients only mix in the head(s) immediately prior to injection thereof into the space between the sleeve and the elongate body.

The elongate body to which the jacket is applied in the method according to the invention is typically a pipeline for use in transporting oil, gas or the like. The jacket may be formed in the method according to the invention either in a production factory or, preferably, on the site in which the jacketed body is to be employed.

The present invention further comprises apparatus for use in the method according to the invention, which comprises: (a) at least one foaming head arranged for mixing of respective foam-forming ingredients and injection thereof into the space between an elongate rigid body and a coaxial sleeve; (b) means for supply of said foaming head with each of said respective foam-forming ingredients; and (c) drive means for driving said foaming head longitudinally along said space.

In a first embodiment of the invention, both the foaming head(s) and the reactant supply means may both be driven along the space between the rigid body and the sleeve; in a second embodiment of the invention, the foaming head(s) may be moved along said space but with the supply means being provided external thereto. In this latter embodiment, the sleeve may be provided with a longitudinally extending slit, the edges of which are continuously separated as the foaming head(s) travel along the space between the rigid body and the sleeve; preferably the edges of the slit are sealed in advance of injection of the foam-forming ingredients into the space mentioned above.

In a third embodiment of the invention, the apparatus is provided with means for forming the sleeve from plastics sheet, said means preferably comprising a shaped external guide portion (connected to such foaming head) and arranged to deform said plastics sheet, as the apparatus moves relative thereto, such that said sleeve is formed with abutting or adjacent longitudinal edges, said forming means also comprising a sealing device arranged so as to subsequently seal the sleeve along the longitudinally abutting or adjacent edges in advance of injection of the foam forming ingredients into the space. In this embodiment it is preferred that the forming head(s) are moved along the space with the supply means being provided external thereto.

It is further preferred that in this embodiment the sealing device comprises an extrusion welder.

The present invention will be further described, by way of example only, with reference to the accompanying drawings, in which: Figure 1 is a schematic longitudinal section of a first embodiment of apparatus for use in the method according to the invention; Figure 2 is a plan view of the apparatus of Figure 1 in the direction of arrow A; Figure 3 is an end elevation of the apparatus of Figure 1, in the direction of arrow B; Figure 4 is a sectional view of the apparatus of Figure 1, along line C-C; Figure 5 is a partially cut-away view of a second embodiment of apparatus for use in the method according to the invention; Figure 6 is a partially cut-away view showing further details of the apparatus of Figure 5; and Figure 7 is a partially cut-away view of a third embodiment of apparatus for use in the method according to the invention.

Referring to Figures 1 to 4 of the drawings, there is shown an elongate pipe 1 having an outer rigid sleeve 2, both the pipe and the sleeve being of discrete lengths sealingly joined end to end.

Beyond the end of the last length of the sleeve 2, and mounted on a protruding length of the pipe 1, is a demountable installation 3 for supply of#hoselines to the space between the sleeve 2 and the pipe 1.

The installation 3 is provided with: (a) a first hose reel 4, which in use is supplied with a first prepolymer (such as a polyol) via first supply conduit 5, the conduit being connected to hoseline 6 wound around the periphery of reel 4; (b) a second hose reel 7 (transversely spaced from the first hose reel 4), the second reel 7 being supplied with a second prepolymer (such as a polyisocyanate) via second supply conduit 8 connected to hoseline 9 wound around the periphery of reel 7; (c) an airhose reel 10 located coaxially between reels 4 and 7, reel 10 having airhose 11 wound thereon; (d) a pair of laterally spaced cable spools 12 each having cable 13 wound thereon, spools 12 and reels 4,7 and 10 all being mounted coaxially within the housing 14 of installation 3, at right angles to the axis of pipe 1; and (e) a motor 15 arranged to wind up spool 12 and also reels 4,7 and 10.

Unwound from spool 12 is a pair of cables 13 which pass around pulleys 28 and then parallel to the axis of pipe 1 along the space between pipe 1 and sleeve 2; unwound from reels 4 and 7 are respectively lengths of hoselines 6,9 and 11 which also pass along the space between pipe 1 and sleeve 2. The trailing end of each cable 13 is secured to a respective fixture 16 provided parallel to the axis of a jig 17, which jig is arranged to be pulled along the pipe as the cable 13 is wound in on spool 12 (when the latter is driven by motor 15).

Housing 14 is secured to ground or other fixed body by securing means 29.

The jig 17 comprises a pair of generally hemicylindrical segments 18, connected by hinge 19, at one edge thereof. There may in some embodiments be more than two segments around the periphery of the pipe; it is particularly preferred to have more than two segments when it is desirable to allow for bends or other irregularies in the pipe 1 and sleeve 2.

In the illustrated embodiment, the two hemicylindrical segments are secured together by locking mechanism 20, diametrically opposed to hinge 19.

Equispaced around the internal cylindrical face of jig 17 are a series of ball races 21 (three thereof being shown in the illustrated embodiment) such that the jig is permitted to move lengthwise of the pipe 1, with rolling contact of the ball races 21 along the outer face 22 thereof.

A corresponding series of ball races 23 are arranged equispaced around the outer periphery 24 of the jig, such that the latter can slide lengthwise of the sleeve 2 with rolling contact with the inner face 25 thereof. The ball races are preferably sprung-loaded, such that they are effectively self-adjusting to provide tolerance for irregularities in either the pipe or the sleeve.

Also equispaced around the jig are a series of injection heads 26 (again three being shown in the illustrated embodiment) for injection of the foam-forming ingredients into the space between the pipe 1 and the sleeve 2. Injection heads 26 are each connected via a suitable mixing head (not shown) to each of hoselines 6,9 and 10 such that the foam-forming ingredients can be supplied from a remote source (not shown) to the respective injection head.

The mixing head (which controls mixing of the prepolymers and air prior to injection of the mixed ingredients into the space between pipe 1 and sleeve 2) is typically of a conventional type known for spraying or injection of polyurethane foam.

Cable 13 is connected to jig 17 by means of the fixture 16 parallel to the axis of the jig 17 (and also along the axis of the pipe 1), such that reeling in of cable 13 about its spool 12 causes translational movement of the jig 17 along the length of the pipe 1; the reeling in of the cable is effected by driving motor 15. The latter is typically a constant torque, variable speed motor, in order to enable the speed of movement of the jig 17 along the pipe 1 to be controlled.

In use, for an initial injection of foam into the space between the pipe 1 and the sleeve 2, a demountable end cap (not shown) is preferably provided initially so as to seal that space. Once a cured annular foam jacket has been formed in the annular space, the cap can be removed as the foam jacket progressively increases in length.

The apparatus described above and illustrated in the accompanying drawings is particularly useful for applying an insulating jacket to an elongate pipeline (typically of carbon steel), the outer sleeve (typically of polyethylene) serving as mechanical protection for the in situ foamed polymer jacket. In use, the pipe and the sleeve are preferably supported above the ground, by fixed supports, rollers or the like, during foam injection, such supports being removed after injection of a discrete length of foam jacket.

Reference will now be made to Figures 5 and 6, which illustrate an alternative embodiment of apparatus according to the invention.

In the arrangement shown in Figures 5 and 6, a jig 30 travels lengthwise along the outside of a pipe 31 and plastics sleeve 32. The jig 30 is supported by a pair of bogies 33 having wheels 33a which travel along rails 34 as the pipe 31 and sleeve 32 are supported by rigid supports 35, each of which has a series of rollers 36 on which the sleeve 32 can rest and slide. Jig 30 is drawn along the outside of the sleeve 32 by a pair of diametrically spaced cables 37 which are driven from respective spools 38 around pulleys 39, by means of a motor (not shown), in housing 40.

Jig 30 has, at its leading edge 41, a wedge element 42, such that as the jig is drawn along the sleeve 32, a split 43 in the latter is separated longitudinally, such that foam-forming ingredients can be injected through the split.

Jig 30 also has a manifold 44 supplied from remote sources (not shown), via hoselines 45,46,47,48, with foam-forming ingredients (such as a polyol and polyisocyanate as described above, and air). The hoselines 45,46,47,48 are themselves supplied from a spool 49 which is coaxial with spools 38, and driven by the same motor. Manifold 44 is connected to foaming heads 50 located in the space between pipe 31 and sleeve 32.

The jig 30 also has a welding head 51 to weld the two parts of the split together along a weld line 53 (see Figure 6); the welding head 51 and the foaming heads are so arranged and operated that the foam-forming ingredients are injected beyond the junction between the weld line 53 and split 43 so that the advancing foam follows the advancing weld line, as the jig 30 travels along the sleeve, to cause production of a foamed jacket 52.

Rails 34 may be provided on a hydraulic platform or the like, such that the pipe may be adjustably raised upstream of the foam injection, so that the pipe may be at an angle of up to 40 (typically about 7 to 10w) to the horizontal, during injection of the foam. The rails may, as illustrated, be toothed to mate with complementary teeth on the wheels 33a on bogie 33.

In the arrangement shown in Figure 7, a jig generally designated 60 comprises an annular cross-sectioned inner guide 70 partially connected along its length to a semi-annular cross-sectioned outer guide 80. The jig 60 travels lengthwise along the outside of a pipe 61 and may be supported on wheeled bogies and rollers as described in the arrangement above and shown in Figures 5 and 6. The semi-annular cross-section of the outer guide 80 serves to deform a plastics (such as HDPE) sheet to form a cylindrical sleeve 64, having longitudinally abutting or adjacent edges 81a and 81b, around the inner ring guide 70. The jig also has a manifold 62 supplied from remote sources (not shown) with foam-forming ingredients via respective hoselines 63 in the manner described in the arrangement above.

The jig also has a preheater 65, to aid deformation of the plastics sheet, and an extrusion welder 66 positioned adjacent the longitudinally abutting or adjacent edges 81a and 81b for joining the edges along a weld line as the jig 60 moves longitudinally relative to the pipe 61.

Four foaming heads 68 are connected to respective elongate feed lines 69, which are fed with the foaming ingredients via passages (not shown) in the inner guide 70 from the hoselines 63 entering the manifold 62. The foaming ingredients can thus be injected into the space between the pipe 61 and sleeve 64 such that the advancing foam follows the advancing weld line as the jig 60 travels longitudinally relative to the pipe 61.

The whole of the apparatus illustrated in Figures 1 to 4, Figures 5 and 6, or Figure 7, is particularly suitable for mobile operation, in that it can all be transported on the back of a suitable vehicle.

Claims

CLAIMS:

1. A method of forming a jacket of foamed polymeric material between an elongate rigid body and a coaxial sleeve, which comprises injecting foam-forming ingredients into the space between said elongate rigid body and said sleeve by means of at least one foaming head which is moved progressively along said space as said foam-forming ingredients react to form a foam.

2. A method as claimed in claim 1, wherein the or each foaming head is provided with separate supplies of foam-forming ingredients.

3. A method as claimed in claim 1 or claim 2 wherein the foam formed is a polyurethane.

4. A method as claimed in any preceding claim, wherein the foam forming ingredients include a polyol, a polyisocyanate and air.

5. A method as claimed in any preceding claim, wherein the ingredients only mix in the head(s) immediately prior to injection thereof into the space between the sleeve and the elongate body.

6. A method as claimed in any preceding claim, wherein the jacket is formed on the site in which the jacketed body is to be employed.

7. A method as claimed in any preceding claim, wherein a longitudinally extending slit is formed in the sleeve, the edges of which slit are continuously separated as the foaming head(s) move progressively along said space.

8. A method as claimed in claim 7, wherein the e#dges of the slit are sealed in advance of injection of the foam-forming ingredients into said space.

9. A method of forming a jacket of foamed polymeric material, substantially as described herein with reference to the accompanying drawings.

10. Apparatus for use in the method according to any preceding claim, which apparatus comprises: (a) at least one foaming head arranged for mixing of respective foam forming ingredients and injection thereof into the space between an elongate rigid body and a coaxial sleeve; (b) means for supply of said foaming head with each of said respective foam forming ingredients; and (c) drive means for driving said foaming head longitudinally along said space.

11. Apparatus as claimed in claim 10, wherein the foaming head(s) and the means for supply of foam forming ingredients are both driven along the space between the rigid body and the sleeve.

12. Apparatus as claimed in claim 10, wherein the foaming head(s) are movable along said space with the supply means being provided external thereto.

13. Apparatus as claimed in claim 10, for use in the method of claim 8, wherein means is provided for sealing the edge of the slit.

14. Apparatus for use in a method of forming a jacket of foamed polymeric material, substantially as described herein with reference to the accompanying drawings.