WO1990007984A2

WO1990007984A2 - Apparatus for treating a pipe

Info

Publication number: WO1990007984A2
Application number: PCT/GB1990/000058
Authority: WO
Inventors: John Wallace Betteridge
Original assignee: GRAYSTON CENTRAL SERVICES Ltd
Current assignee: GRAYSTON CENTRAL SERVICES Ltd
Priority date: 1989-01-13
Filing date: 1990-01-15
Publication date: 1990-07-26
Anticipated expiration: 1991-07-13
Also published as: GB2228432A; GB8900718D0; WO1990007984A3

Abstract

A multi-role machine (10) is disclosed which includes an inductive coil (20), for circumferentially heating a pipe (30) in a number of modes and a spray head (42) for circumferentially spraying a pipe, in the region of a weld (33). The spray head (42) and inductive coil (20) are disposed so that heating and spraying can be conducted simultaneously.

Description

APPARATUS FOR TREATING A PIPE

This invention relates to apparatus for treating a pipe.

Pipelines, for example as used in the oil industry for transporting oil from a production platform to shore, are generally made up of pipe sections which are coated with a corrosion and damage resistant layer or layers during manufacture. As the pipe sections are welded together on site by, for example, a PASSO welding sysi.Hm. the pipe surface in the region of each end of the pipe section needs to be left clear of protective coating so that welding can take place.

There has been proposed, for example in US 4038942 and GB 2044135, apparatus for spraying a powder coating circumferentially around a pipe in the region of a weld, such apparatus including a powder sprayer mounted on a yoke which grips the circumference of the pipe and includes a driving mechanism which engages the surface of the pipe to drive the yoke around the circumference.

However, it is a disadvantage of this apparatus that it is necessary, separately, to heat the pipe prior to spraying so that the sprayed powder will then cure on contact with the pipe surface. It is a further disadvantage of such apparatus that the spraying technique does not take into account the physical characteristics of the weld.

According to the invention in a first aspect there is provided apparatus for treating a pipe comprising, an inductive coil for receiving a said pipe and spray means for spraying a circumferential coating on a said pipe, the spray means including a spray head disposed radially inwardly of the inductive coil.

According to the invention in a second aspect there is provided apparatus for spraying a pipe comprising a spray head, an arcuate track, and driving means for driving the spray head around the track.

According to the invention in a third aspect, there is provided a spray head for spraying a coating, the head comprising first and second nozzles, the field of spray of the nozzles having an overlapping region.

According to the invention in a fourth aspect, there is provided a spray head for spraying a coating, the head comprising at least one nozzle, the nozzle being disposed in a chamber having a re-entrant rim defining a spray opening and the nozzle including a first opening facing the spray opening and a second opening, facing a wall of the chamber.

According to the invention in a fifth aspect, there is provided apparatus for treating a pipe comprising a frame for receiving a pipe, a stationary inductive coil for heating a said pipe and spray means including a movable spray head for spraying a coating on the heated pipe, the inductive coil and spray means being coupled to the frame.

According to the invention in a sixth aspect, there is provided a multi-role machine comprising means for spraying a coating maLerial circumferentially around a pipe, means for heating a circumferential section of a said pipe, control means for controlling the heating means so as to heat the pipe in a first mode to a first temperature for a first length of time, for heat treating a joint between two pipe sections and in a second mode for heating a pipe to a second temperature for a second length of time while said spray means is spraying the pipe, for curing the coating material.

According to the invention in an seventh aspect, there is provided a method of spraying a pipe .comprising the steps of: heating an area of the pipe; spraying a coating material on the pipe, the spraying step being performed at least partially at the same time as the heating step is performed.

In addition to coating pipe welds in the manner described, it is also necessary, once welding has taken place and prior to coating, for the heat affected zone to be annealed so as to take out residual stresses. Apparatus for performing this function has been proposed which uses an inductive coil. However, it is a disadvantage of such apparatus that the characteristics of the coil are difficult to adjust and the apparatus is inflexible in that it can only be used for pipes of a specific diameter.

According to the invention in a eighth aspect there is provided an apparatus for heating a pipe comprising a frame, an inductive coil coupled to the frame, the coil forming at least one loop for receiving a said pipe and wherein the size of said at least one loop is adjustable,

According to the invention in a ninth aspect, there is provided a kit of parts comprising: a first set of inductive coil sections, a second set of inductive coil sections, at least one connector for connecting a said set of sections together and wherein the coil sections of the first set, when connected form a coil having a larger loop size than the connected sections of the second set.

According to the invention in an tenth aspect there is provided an inductive coil comprising at least one loop formed from a plurality of coil sections connected together by connectors, the coil sections including par.uageways for liquid coolant and the coil further comprising a further passageway for connecting the passageways of two said coil sections, the passageways of the connected coil sections not being bridged by a said connector and wherein said further passageway comprises first and second bores formed in respective connectors and a link connecting said bores.

An embodiment of the invention will now be described, by way of example, with reference to the accompanying drawings in which:

Figure 1 is a block diagram of the major components of an embodiment of the invention;

Figure 2 is a side elevation of the embodiment of the invention, shown engaging a pipe;

Figure 3 is a sectional view taken in the direction of arrow 3 of figure 2; Figure 4 is a view, on an enlarged scale, of the inductive coil of figure 1;

Figure 5 is a sectional view across 5-5' of figure 4;

Figure 6 is a simplified plan view in the direction of the arrow 6 of figure 4 showing the contact arrangement of the inductive coil of figure 4;

Figure 7 is a plan view of the spray head of the embodiment of l.he invention; and

Figure 8 is a sectional view taken across 8-8' of figure 7.

Figure 9 is a view taken in the direction of arrow 9 of figure 2, showing the rotation mechanism for the powder spray head.

Figure 10 is a view taken in the direction of the arrow 10 of figure 9.

With reference to Figure l_r a block diagram of the major components of an embodiment of the invention is shown. The embodiment of the invention is a universal machine which can be used both for the heat treatment of girth welds between two pipe sections before and on completion of the welding operation and for girth weld powder spraying.

The machine, generally designated 10, is powered by an external power source 90 and comprises an inductive heating coil 20, defining a passage arranged to receive a steel pipe 30 which includes two pipe sections 31,32 connected by means of a girth weld 33. The inductive coil is used for pre-heating of the ends of the sections 31, 32 prior to welding, for stress relieving heat treatment of the weld 33 after welding and for heating the weld area during the subsequent application of a protective coating material. The coil 20 is connected to a known art coil controller 70 for controlling input power e.g. in the range 50-300kw at frequencies from 500Hz to lOKHz and pipe temperature, by means of a suitable sensor/control loop (not shown). The controller 70 also includes a timer, for controlling the power ON time as is described below and, preferably, a hard copy read out to record the treatment performed. Power to the coil controller 70 is provided via a known art matching unit 80 which matches the frequency and impedance of the power source to the inductive coil load.

The machine 10 further includes a powder spray mechanism 40 including a spray head 42, an arcuate, part annular track 44 and a motor 47 and transmission gearing 46 connecting the head 42 to the track 44 for driving the head 42 circumferentially around the pipe 30. The spray head 42 is connected to a known art fluidized bed 50 which provides powder in a pressurized airstream to the head 42, the fluidized bed 50 and the spray mechanism 40 being controlled by means of a known art spray controller 60, which interfaces, during a spraying operation, with the other controlled operations of the machine.

A liquid coolant circuit, to the inductive coil 20 and spray head 42 is also provided, although this is not shown. An openable frame, for mounting the active machine components on or relative to the pipe 30 is provided, generally designated by box 15 and all components shown within the box are mounted on the frame. Control means 65, for opening and closing the frame is also provided.

A general arrangement of the embodiment of the invention is shown in figure 2 and will now be described in detail.

The main frame 15 is manufactured from welded aluminium and is of a 'clam' type design including three substantially similar jaw mechanisms generally designated 106, 108. 109. Jaw mechanism 106 is shown in more detail in figure 3 and includes two jaws 111, 110 which each comprise two jaw members 112. 113; 114, 115.

Jaws 111, 110 are hingably mounted so as to be rotatable about a pivot 116 on which a twin-bladed yoke 118 is also mounted. The jaws 111, 110 are connected to the yoke 118 by means of pneumatic rams 120, 122 (one ram connected to each blade) and joints 124, 126; 128, 130. Operation of the rams will cause the jaws 111, 110 to open or close about the pivot 116.

The jaws, when closed, cause the whole frame 15 to engage the pipe 30 as shown in figs. 2 and 3 and when open, allow the machine to be removed from the pipe 30.

In order to engage the surface of the pipe 30 accurately, jaw mechanism 106 is provided with four rollers 130. 132. 134. 136. rollers 130. 136 being connected via a yoke 138 to pivot 116 and rollers 132. 134 being connected to a respective jaw 111. 110. The rollers are radially adjustable to allow for different pipe sizes.

The jaw mechanisms 106, 108 are substantially identical and serve to mount the frame relative to the pipe. However, the jaw mechanism 110 is not provided with any rollers and thus the part of the frame between jaw mechanisms 108. 110 is cantilevered This enables the machine to clear a weld coated by the spray head 42, as is described below, without any rollers running over the newly applied coating.

All the left or right-hand jaws, are connected together by means of longitudinal lower support frames 140, 141, and upper support members 142, 143 to form two rigid hingably connected frame halves. The whole frame is supported from a girder 144 by means of cables 145 connected to connection points 151-156 on the support members 142, 143. The girder 144 is preferably suspended from a gantry crane to allow the machine to be raised or lowered.

In the closed position, as shown in figure 3. the jaw mechanisms do not close completely around the pipe but a gap 160 is left, so that an electrical circuit is not formed by the frame about the pipe, which would affect the operation of the inductive coil 20.

Jaw mechanisms 106, 109 further include stabilizing legs 170-173 for preventing rotation of the device about the pipe once engaged therewith, the stablizing legs 170-173 being adjustable in length so as just to engage the ground when the machine is in position.

The 'active' components of the machine, which are mounted on the frame 15, will now be described.

Induction Heating Coil

The coil 20 is designed and manufactured as a multi-turn coil split at top and bottom into two sections , each section being connected between jaws of adjacent jaw mechanisms 108, 109 of frame 15.

The coil 20 is shown in more detail in figures 4-6 and comprises a plurality of coil sections 210-219, formed from copper tubing and provided at each end with a nipple connector. The coil sections 210-219 are connected electrically in a helical pattern, following the number order of the coil sections. The coil sections 210-219 are connected to each other by upper 220-229 and lower 220'-229' contacts of which the upper contacts 220-229 is shown in figure 6. The contacts are connected to the respective coil section having the same reference numeral, less 10. Two further upper and lower contacts 230, 231; 230', 231' are further provided although these are redundant in the present embodiment.

The contacts can be notionally divided into four sets (left upper and lower, right upper and lower) and the sets are each connected to the frame 15 by a respective channel shaped aluminium extrusion 234, 235, 236. 237 in the same manner as now described with reference to the set Of contacts 220. 222, 224, 226, 228, 231,

Contacts 220/2/4/6/7/31 are mounted in a castellated block 232 of a non-conductive material, for example TUFNOL. The TUFNOL block 232 is received in the aluminium channel 234 with the channel 234, TUFNOL block 232 and contacts 220/2/4/6/8/31 being screwed together by means of bolts 240-245. The bolts 240-245 engage respective contacts 220/2/4/6/8/31 and draw the contacts against the TUFNOL block 232 via rubber pads (or other resilient members) 250-255, this providing some conformability when the contacts 220/2/4/6/8/31 are respectively engaged with contacts 230/221/3/5/7/9 as shown in fig. 6.

The engagement surfaces of the contacts have a modified keystone configuration including first and second parallel portions 260, 261 spaced one from the other and a diagonal interconnecting portion 262. This arrangement ensures self alignment of the contacts when the frame is closed.

Adjacent pairs of contacts (for example 221. 222 and 223, 224) have mirror image engagement surface configurations to assist engagement and alignment.

Four support members are provided for connecting the coil to the frame, two for each side, at each end of the inductive coil, these being designated 280-283 in figures 4 and 5.

The aluminium channel 234 includes end plates 270, 271 which are each tapped for receiving four bolts 272-275, to hold the channel between adjacent support members 280,282, a similar arrangement being provided for the other channels 235-7..

The support πiombers 280-283 are connected by means of bolts, to adjacent jaw mechanisms 108, 109, support member 280 being connected to one jaw of jaw mechanism 109, support member 281 being connected to the opposed jaw of jaw mechanism 109, support member 282 being connected to one jaw of jaw mechanism 108 and support member 283 being connected to the opposed jaw of support mechanism 108, as shown in figure 2.

The bolts for mounting the support members relative to the jaws are received in elongate slots 285 in the support members, this allowing a coarse adjustment of the relative position of the engaged contacts when the jaw mechanisms 108, 109 are closed (the rubber pads e.g. 250-255 providing a fine adjustment).

In use, when the jaw mechanisms 106,8.9 are opened, the inductive coil splits at the upper and lower contacts and, when engaged with the pipe, the contacts engage each other as shown in figures 5 and 6 to complete a helical electrical circuit between contacts 220 and 229. As contacts 230, 231 are not necessary for completion of the helical circuit, these can be used to connect power supply connections to the coil.

The connection of a power supply of a predetermined power and frequency, matching the impedance of the coil will, as will be apparent to one skilled in the art, generate an inductive field which will be concentrated within the bounds of the coil. If, as shown in figure 2, a pipe is introduced into the coil, this will be consequently heated in dependence upon the power provided to the coil. The coil can then be used for several pipe heating applications as is described below.

In addition to the coil electrical circuit, due to the high temperatures to which the coil is subjected, a liquid cooling circuit is provided. As the coil sections 210-219 are formed by copper tubes, these provide a convenient passageway for liquid coolant. However, it is impractical to provide liquid passageways across the electrical contacts and separate liquid passageways, which do not bridge engaged contacts are provided as shown in figures 4 and 5. The passageways are arranged to conduct the cooling liquid in two sub-circuits, the first being from inlet port 286, through passageway 287 in contact 228'. to coil section 218. to passageway 288 in contact 228, through connecting tube 289. to passageway 290 in contact 226 to coil section 216 and so on through the remaining passageways coil sections and connecting tubes, all of which are formed on one side of the inductive coil, shown on the left of figure 5,the cooling liquid exiting through outlet port 291. In order to prevent electrical connection between the contacts, the connecting tubes (e.g. 289) between the various contacts are formed from insulating material, for example reinforced rubber.

Thus, between inlet port 286 and outlet port 291, a continuous liquid circuit is formed. The outlet port 291 is then connected by means of a flexible reinforced rubber tube 292 to an inlet port 293 of the second sub circuit on the opposed side of the coil (the inlet port

293 being formed in contact 229). The arrangement of coil sections and passageways is then substantially the same as that previously described, with the outlet port

294 of the second sub circuit being formed in contact 230', thus forming a complete coolant circuit.

In order to adjust the axial coverage of the inductive coil, selected ones of the rubber connecting tubes 289 may be replaced by corresponding copper tubes which will then have the effect of shorting out the coil sections between the two thus connected contacts (for example in figure 4, if rubber connecting tube 289 as replaced by a corresponding copper tube this would provide a short between contacts 228 and 226, thus shorting out coil sections 217 and 216.

The sectional construction of the inductive coil as described above has particular advantages in that by replacement of the coil sections 210-219 and support members 280-283, the overall size of the inductive coil can be changed to suit the diameter of pipe being treated. For example, if it is desired to heat treat a smaller pipe, the coil 40 is unbolted from jaw mechanisms 108, 109. The support members 280-283 are then removed as are coil sections 210-219. The coil sections are then replaced by similar sections of reduced radius. New support members, to accomodate the reduced size coil are then attached to channel members 234-7. the support members then being rebolted to the jaw mechanisms 108. 110. No other replacement of parts is required. Such coil replacement, or adjustment of axial coverage; will alter the inductance of the coil as a whole and this will require some adjustment in the matching unit 80 so that efficiency of the coil is substantially maintained, as will be apparent to one skilled in the art.

Spray Mechanism

The spray mechanism 40 as shown generally in figure 1 and in more detail in figures 2, 7. 8, 9 and 10 comprises a spray head, generally designated 42 which is mounted, via a support 480, on an annular toothed track 44, the spray head 42 being provided with a motor 47 and transmission 46 for engaging the track, so that the spray head 40 can move around the circumference of the pipe 31.

The spray head 42 is shown in more detail in figures 7 and 8 and comprises two spray nozzles 410, 412 spaced longitudinally, in the axial direction of the pipe 31. In use, the pipe 30 is positioned so that the weld 33 lies midway between the nozzles 410, 412.

Nozzle 410 is shown in figure 8 and it will be understood that nozzle 412 is identical save that it is disposed at a different position. Nozzle 410 comprises a hollow cylindrical barrel, provided with a knurled head 422. The barrel 420 is screwed into a corresponding opening 424 in a. spray head housing 414, the barrel 420 and housing 414 being provided with complementary threaded portions for engagement. Once engaged in the housing, a nozzle head 430 is press fitted (with an interference fit) onto the barrel 420 as shown in figure 8. The barrel 420 is provided with a circular lateral opening 440 which communicates with a cylindrical passageway 442 formed in the housing 414. The passageway 442 provides an inlet for the fluidized powder, from the fluidized bed 50. A similar cylindrical passageway 444 is provided for head 412, as shown.

The end of the barrel 420 adjacent to the nozzle head 430 is provided with four openings 450, 452, 454, 456. Openings 454, 456 are longitudinally arranged with, openings 450, 452, being perpendicular to openings 454, 456. The openings 450-456 discharge fluidized powder substantially perpendicular to the weld, into a recessed swirl chamber 460 (an interconnecting swirl chamber 462 being provided for nozzle 412). The swirl chambers 4.60, 462 have a reentrant lip 464 which acts to deflect the fluidized powder from openings 450,2,4,6 in the manner shown by the arrow A in figure 8. Powder discharged in this manner is forced up against the sides of the weld, so that powder is applied to the weld from several directions.

Openings 454, 456 are made larger than openings 450, 452, in dependence upon the shape of the swirl chamber so that the distribution in the swirl chamber 460 of fluidized powder which is forced through these openings is substantially uniform.

Nozzle head 430 is provided with a venturi shaped direct spray opening 458, which in use faces the pipe 30. The diameter of the opening at its narrowest point regulates the flow of powder from the nozzle directly onto the weld. The angle of the frusto conical section 459 of opening 458 defines the width of spray through this opening. This is chosen, in combination with the distance D between the centres of the two nozzles 410, 412, so that a substantial overlap, (25%) between the direct spray regions of both heads is provided.

As the nozzle head 430 is a push fit onto barrel 420, replacement of the nozzle head, with one with a large sized opening 458 or a different spray angle is a simple measure, so that the spray characteristics of the nozzle can be easily adjusted. As shown in figure 2, the spray head 40 is disposed between the inductive coil 20 and the pipe 30. This allows both heating and spraying to be performed simultaneously thus improving the quality of the coating, particularly if coating is taking place in cold climates. The spray head 40 is formed from TUFNOL, or another suitable non-conductive material so that it will not affect the performance of the coil 20.

In order to cool the head 42, a liquid coolant circuit comprising interconnecting bores 470, 472, 474 is provided, the bores being stopped at their distal ends 476 to provide a single circuit. In order to provide further cooling, air may be continually purged through the fluid powder bores, when spraying is not taking place.

The spray head 40 is connected to the drive mechanism 46 via an extruded aluminium support 480 which, in use, lies outside the line of the inductive coil 20, the support 480 including four bores corresponding respectively to the two fluid powder bores 440. 444 and liquid coolant circuit bores 470, 474.

The fluid powder supply, liquid coolant connections and power supply and control for the head moving mechanism 47 are supplied through a single control umbilical connecting with the fluidized bed and spray control modules 50, 60.

The driving mechanism for the spray head 42 is shown in figures 9 and 10.

The aluminium support member 480, to which spray head 42 is attached, is welded, at one end, to a radially disposed arm 481. The arm 481 is connected to a part-annular runner 484 by means of bolts 483. The runner 484 is arranged to slide in the track 44. The track 44 is also of part annular construction, extending for 180° circumferential angle and has a channel shaped cross section, the base of the channel being indicated by phanthom line 485. A spacer 487 is provided between runner 484 and arm 481. so that the arm 481 clears the side of annular track 44.

The runner 484 is provided on its radially outward facing surface with a toothed rack 489. The rack 489 meshes with cogs 490,491 which are connected by respective drive belts 492, 493, pulleys 494,495 and a drive shaft 496 to motor 47, so that rotation of motor 47 will cause cogs 490,491 to rotate thus forcing rack 489, runner 484 and spray head 42 to orbit pipe 30.

It should be noted that rack 289 of runner 284 extends for a circumferential angle of 285°. Cogs 490,491 are 85° apart. As the sum of these angles exceeds 360° it will be apparent that as the runner 484 rotates about pipe 30, the rack 489 will always be in engagement with one or both of the cogs 290. 291, so that the runner 484 will continue to be driven through all angles of rotation. If half angle rotation is all that is required, the angular sum need only exceed 180°.

In order to accomodate various pipe sizes, for example those designated by 30'.30'*, the arm 481 is provided with two elongate slots 482 which bolts 483 engage, to allow radial adjustment of the position of the spray head 42.

The track 44 is connected, via spacers 486, to one jaw. labelled 488. of jaw mechanism 109. as as not to inhibit opening of the frame.

Preferably, the spray controller includes a 'null' setting which adjusts the position of the runner so that opening 497 between the ends of the runner is at the lowermost position, to allow the machine to be upwardly removed from the pipe.

The track and movement mechanism as described above is of a generally similar character to that of a pipe bevel cutter manufactured by H & M Pipe Bevel Cutting Company. Fluidized Bed and Control Modules

The longitudinal lower support frames 140, 141 are provided with laterally extending grooves 180 which are arranged to receive runners 190 connected to the base of machinery modules, e.g. the fluidized bed 50, spray controller 60. frame controller 65, coil controller 70 and matching unit 80, as shown, so that these units can be racked into the frame for connection to the coil/spray head mechanism.

The fluidized bed is of a known art design and is preferably of a split tank construction so that the machine may be used, for example, to spray either Fusion Bonded Epoxy (FBE) or sintered polyethylene (PE) coating materials separately or in a layered coat, for example that of the Mannesman MAPEC System, if required

The spray controller 60 includes powder flow control valves for controlling the flow to respective nozzles 410, 412, and air pressure regulators, controlling the pressure to the power flow control valves.

The spray controller also controls the position of powder spraying and specifically controls the motor 47 to drive the spray head 42 around the pipe. Preferably, the spray head 42 is driven for one revolution in one direction, followed by a revolution in the reverse direction, this being repeated until the required coating is obtained. Alternatively the spray head 42 may be driven in alternate half revolutions.

The induction coil controller 70 and matching unit are also of known art design. The controller 70 includes timers and remote sensors (e.g. optical pyrometers) for performing weld heating for different times and at different temperatures depending upon the task undertaken. For example, for a 12 inch pipe having 3/4 inch wall thickness:

1) If it is desired to pre-heat the ends of pipes prior to welding, inter-pass heating to 100°C for 60 sees, is performed.

2) Tf the coil 20 is to be used for stress relieving on completion of a weld, heating at a temperature between 600-700°C for 3 minutes is performed.

3) If heating whilst spray coating is performed, a temperature of 240°C for 90 sees, is required. Preferably, the induction heating commences up to 30 seconds before spraying commences, with the heating continuing for at least five seconds after spraying commences, using suitable timers incorporated in the coil and spray controllers, for example a "heating" timer, for controlling the heating time, a "spray" timer for controlling the spray time and a "gap" timer for controlling the time after starting of the heating timer, before the spray timer starts.

The frame controller 65 includes an air compressor for operating the hydraulic rams, with suitable control electronics.

The machine described above is suitable for use with pipe sections which already have a thin protective coating applied to their surface (apart from the weld area). If it is desired to coat weight coated pipe (i.e. a pipe composed of sections coated, except for the weld area, with a concrete jacket), the machine can be modified by removing modules 50-80 and dismantling the components of the longitudinal frame/support members 140-143 between jaw mechanisms 106,108 and connecting the jaw mechanisms 106, 108 to one another, thus shortening the overall length of the frame. This will allow the machine to be located on the weld area at which the concrete jacket is cut back. The racked in items in this case are then supplied as free standing modules. In use, the machine is placed on a pipeline laying barge which performs the operations of welding the pipe sections together, heat treating them, coating the welded area and then paying out the completed pipeline over the stern of the barge and directly into the sea. Thus, in use, several machines as described could be used on such a barge, one providing inter-pass heating of the end of pipes prior to welding, the second providing stress relieving heating on completion of a weld and a third providing the weld coating. All machines are preferably secured to the barge, so that the machine moves with the barge, with the pipe effectively remaining stationery and moving past the various machine workstations. However, if it is desired to use the machine on land, the frame can be motorized so as to move along a static pipe performing the various operations described above.

The interchangability of the induction coils allows the machine to be used for a range of pipe sizes. However, advantageously, three sizes of general machine frame are provided for dealing with pipe sizes in three ranges, namely 76-457 millimetre, 457-914 millimetre and 914-1422 millimetre.

In some applications, the contact sets nearest the jaw mechanism pivot may be dispensed with, the coil sections then flexibly accommodating the hinged movement of the jaw mechanism.

Claims

CLAIMS :

1. Apparatus for treating a pipe comprising a frame for receiving a pipe, a stationary inductive coil for heating the pipe and spray means including a movable spray head for spraying a coating on the heated pipe, the inductive coil and spray means being coupled to the frame.

2 . Apparatus as claimed in claim 1 wherein the frame includes guiding means for guiding a said pipe therethrough.

3. Apparatus as claimed in claim 2 wherein the guiding means comprises at least one plurality of rollers for engaging the pipe.

4. Apparatus as claimed in claim 2 or claim 3 wherein the inductive coil and spray means are disposed on a cantilevered portion of the frame.

5. Apparatus as claimed in any one of claims 1 to 4 wherein the frame comprises at least one jaw mechanism for engaging a said pipe, the mechanism comprising first and second pivotably connected jaws.

6. Apparatus as claimed in claim 5 further comprising means for opening and closing the jaws.

7. Apparatus as claimed in any one of claims 1 to 6 wherein the frame includes at least one bay for receiving an equipment module.

8. Apparatus as claimed in claim 4 wherein the or each bay includes plurality of guides for receiving respective runners provided on a said module.

9. Apparatus as claimed in any one of claims 1 to 8 wherein the frame is suspended from a support.

10. Apparatus as claimed in claim 9 wherein the frame includes a plurality of stabilizers.

11. Apparatus as claimed in any one of claims 1 to 10 further comprising a plurality of equipment modules for use with the inductive coil and/or spray means.

12. Apparatus as claimed in claim 11 wherein said equipment modules include a powder fluidizing bed of said spray means.

13. Apparatus as claimed in claim 12 wherein the bed includes first and second coating material resevoirs and valve means for selecting a said coating material reservoir.

14. Apparatus as claimed in claim 13 wherein the coating materials comprise at least one of Fusion Bonded Epoxy and Polyethylene.

15. Apparatus as claimed in any one of claims 11 to 14 wherein the modules include an induction heating coil controller.

16. Apparatus as claimed in claim 15 wherein the induction heating coil controller includes means for controlling the heating time and/or heating temperature of the coil.

17. Apparatus as claimed in any one of claims 11 to 16 wherein the modules comprise a matching unit for matching the characteristics of a power supply to those of the coil.

18. Apparatus as claimed in any one of claims 11 to 17 wherein the modules include a spray controller.

19. Apparatus as claimed in claim 18 as dependent on claim 15 wherein the spray and coil control modules include a heating timer for controlling the heating time, a coating timer for controlling the coating time. - and a gap timer, the gap timer being started when the heating timer is started and the coating timer not being started until the gap timer has timed out.

20. Apparatus as claimed in any of the preceding claims wherein the spray means is arranged to spray a circumferential coating on the said pipe and the spray head is disposed radially inwardly of the inductive coil.

21. Apparatus as claimed in any one of the preceding claims wherein the spray head comprises at least one nozzle, the or each nozzle being disposed in a chamber having a re-entrant rim defining a spray opening and a nozzle including a first opening facing the spray opening and a second opening, facing a wall of the chamber.

22. Apparatus as claimed in any one of claims 1 to 20, wherein the head comprises first and second nozzles, the field of the spray of the nozzles having an overlapping region.

23. Apparatus as claimed in any one of the preceding claims wherein the coil forms at least one loop for receiving a said pipe and wherein the size of said at least one loop is adjustable.

24. Apparatus as claimed in claim 23 wherein the coil comprises a plurality of coil sections connected together to form said at least one loop.

25. Apparatus as claimed in claim 24 wherein the frame is openable and further comprising at least one connector coupled to the frame, the or each connector disconnecting the or each loop of the coil when the frame is opened.

26. Apparatus as claimed in claim 25 wherein the position of the or each connector relative to the frame is adjustable.

27. Apparatus as claimed in claim 25 or claim 26 comprising first and second said connectors, the coil sections being disposed between said connectors.

28. Apparatus as claimed in claim 27 wherein the connectors are diametrically opposed.

29. Apparatus as claimed in claim 27 or claim 28 wherein the coil sections are removably connected to the or each connector.

30. Apparatus as claimed in any one of claims 24 to 29 wherein the coil sections include respective passageways - for liquid coolant.

31. Apparatus as claimed in claim 30 further comprising at least one further liquid passageway connecting the passageways of two said coil sections.

32. Apparatus as claimed in claim 31 wherein the connected passageways of the coil sections are not bridged by a said connector.

33. An assembly as claimed in claim 32 wherein said further passageway comprises first and second passageways formed in respective connector components and a link connecting said passageways.

34. Apparatus as claimed in claim 33 wherein the link is formed from non-electrically conductive material.

35. Apparatus as claimed in claim 34 wherein the link is selectively replaceable with a corresponding link formed from conductive material whereby the power of the inductive coil is adjustable.

36. Apparatus as claimed in any one of the preceding claims wherein the spray means further comprises an arcuate track, and driving means for driving the spray head relative to the track.

37. Apparatus as claimed in claim 36 wherein the spray head is connected to an arcuate support, the support running on the track.

38. Apparatus as claimed in claim 37 wherein the driving means includes first and second circumferentially spaced rotational members arranged to engage the support and impart movement thereto.

39. Apparatus as claimed in claim 38 wherein the rotational members comprise cogs and the support is provided with a rack for engagement with the cogs.

40. Apparatus as claimed in any one of claims 37 to 39 wherein the circumferential angle by which the rotational members are spaced and the circumferential angular extent of the support together exceed an angular value of at least 180°.

41. Apparatus as claimed in claim 40 wherein said angular value exceeds 360°.

42. Apparatus as claimed in any one of claims 36 to 41 wherein the arcuate track describes a circumferential angle of substantially 180°.

43. Apparatus as claimed in any one of claims 36 to 42 where dependent directly or indirectly upon claim 5 wherein the arcuate track is connected to only one of the pivotably connected jaws of a said jaw mechanism.

44. Apparatus as claimed in claim 36 further comprising control means for controlling the driving means to drive the spray head in sequentially contra rotating revolutions or part revolutions.

45. Apparatus as claimed in any one of the preceding claims wherein the position of the spray head is radially adjustable.

46. An apparatus for heating a pipe comprising a frame, an inductive coil coupled to the frame, the coil forming at least one loop for receiving a said pipe and wherein the size of said at least one loop is adjustable.

47. A kit of parts comprising: a first set of inductive coil sections, a second set of inductive coil sections, at least one connector for connecting a said set of sections together and wherein the coil sections of the first set, when connected form a coil having a larger loop size than the connected sections of the second set.

48. An inductive coil comprising at least one loop formed from a plurality of coil sections connected together by connectors, the coil sections including passageways or liquid coolant and further comprising further passageway for connecting the passageways of two said coil sections, the connected coil sections not being bridged by a said connector and wherein said further passageway comprises first and second bores formed in respective connectors and a link connecting said bores.

49. Apparatus as claimed in claim 48 wherein the link is formed from non-electrically conductive material.

50. Apparatus as claimed in claim 49 wherein the link is selectively replacable with a corresponding link formed from conductive material whereby the coverage of the inductive coil is adjustable.

51. Apparatus for spraying a pipe comprising a spray head, an arcuate track; and driving means for driving the spray head around the track.

52. A spray head for spraying a coating, the head comprising first and second nozzles, the field of spray of the nozzles having an overlapping region.

53. A spray head for spraying a coating, the head comprising at least one nozzle, the nozzle being disposed in a chamber having a re-entrant rim defining a spray opening and the nozzle including a first opening facing the spray opening and a second opening, facing a wall of the chamber.

54. Apparatus for treating a pipe comprising, an inductive coil for receiving a said pipe and spray means for spraying a circumferential coating on a said pipe, the spray means including a spray head disposed radially inwardly of the inductive coil.

55. A multi-role machine comprising means for spraying a coating material ci cumferentially around a pipe, means for heating a circumferential section of a said pipe, control means for controlling the heating means so as to heat the pipe in a first mode to a first temperature for a first length of time, for heat treating a joint between two pipe sections and in a second mode for heating a pipe to a second temperature for a second length of time while said spray means is spraying the pipe, for curing the coating material.

56. A method of spraying a pipe comprising the steps of: heating an area of the pipe; spraying a coating material on the pipe, the spraying step being performed at least partially at the same time as the heating step is performed.

57. Apparatus for treating a pipe substantially as hereinbefore described with reference to any one of the accompanying drawings.

58. A method of treating a pipe substantially as hereinbefore described with reference to any of the accompanying drawings.