PIPE COATING APPARATUS

Abstract: Pipes (15, 15') of the type used in subterranean or submerged pipelines for the recovery of oil, gas, slurries or like pipe transportable materials from a subterranean well are coated sequentially in a flood coating station booth (20) including a catchment tray (40) for collecting excess coating for recycling, and pipe handling means adapted to contact a pipe at predetermined times and in a predetermined manner permitting the pipe to be progressively advanced through the coating booth without the need for pipe supports passing under the flood coating which avoids the integrity of the applied coating becoming compromised by the pipe handling means and minimises the risk of the handling apparatus becoming fouled by coating spillage.

Description: Pipe Coating Apparatus This invention is concerned with the coating of pipes of the type used in subterranean or submerged pipelines for the recovery of oil, gas, slurries or like pipeable materials from a subterranean well. In particular, though not exclusively, it is concerned with pipes in which a steel pipe section is covered with a bituminous-type anti- corrosion coating. In a typical coating method uniform lengths of steel pipe are accumulated for coating and each in turn is lifted, e.g. by overhead crane, on to conveyor means for individual coating treatment. The conveyor means causes each pipe to rotate about its longitudinal axis while it is passed longitudinally past different treatment stations. Typically the pipes are pre-heated to remove all moisture before being shot blast cleaned to remove all dirt and foreign matter in order to ensure an optimum coating-to-pipe bond. A primer is then applied by a measured spray. Thereafter a bituminous-type coating, usually asphalt or coal tar, is poured as a flood coat over the rotating pipe. A glass fibre inner wrap followed by an asbestos felt, glass fibre or glass cloth outer wrap can be simultaneously wound on to the pipe during the coating process. Finally whitewash or a similar solar protection agent is then applied to the coated pipe to prevent adhesion between adjacent pipes and to minimise the effects of direct sunlight upon the integrity of the coating. A standard inspection is then carried out to check the dielectric strength, bonding and thickness of the coating. Pipes coated thus and reinforced with the necessary glass fibre inner wraps and felt or glass outer wraps provide adequate protection for normal in line temperatures of up to 80°C (coal tar) or 70°C (asphalt) maximum for oil, gas or water lines. The known flood coating method is wasteful and causes excessive mess due to the spillage around the pipe of the bituminous type coating. The handling of the pipe during the coating step is also difficult to automate satisfactorily. Furthermore the pipe handling apparatus such as support buggies become fouled with the coating during the passage thereof beneath the coating applicator. An object of the present invention is to provide improvements in the coating of such pipes, and generally obviate or mitigate the aforesaid difficulties of the known coating processes. Thus according to the present invention there is provided apparatus for the coating of pipes sequentially in a flood coating booth which solves the aforesaid problems by firstly including a catchment tray for collecting excess coating for recycling, and secondly providing unique pipe handling means adapted to contact the pipe at predetermined times and in a predetermined manner permitting the pipe to be progressively advanced through the coating booth without the need for pipe supports passing under the flood coating which avoids the integrity of the applied coating becoming compromised by the pipe handling means and minimises the risk of the handling apparatus becoming fouled by coating spillage. SUBSTTTUTESHEET(RULE26) According to the invention said handling means includes a pipe feed mechanism for introducing a pipe lengthwise in the direction of its longitudinal axis to the coating booth whilst simultaneously applying an appropriate degree of rotation about that longitudinal axis, which mechanism has a pipe hold-down feature whereby the leading end of the pipe is permitted to project freely into the booth whilst another part of the pipe is restrained to avoid the pipe toppling into the booth due to lack of support at the leading end, and said handling means further includes at least first and second pipe end supports for picking up the coated pipe as it exits the coating booth. . The first and second pipe end supports are provided on remote controlled vehicles which are preferably rail guided, and independently operable to convey respectively the leading and trailing ends of the pipe as it emerges from the coating booth. Thus it will be recognised that the pipe enters the booth as an unsupported overhang which is readily flood or curtain coated since no support mechanism can interfere with the application of the coating. The remote or trailing end of the pipe which has not yet entered the booth is subject to a "hold down" to stabilise the pipe delivery for coating purposes. As the pipe emerges from the coating booth a first end support device is activated to contact the leading end of the pipe and convey it on a remotely .controlled vehicle away from the booth. After a suitable time delay (calculated to be about the time the trailing end of the pipe emerges from the coating booth) , a second support device is activated to contact the trailing end of the pipe and convey it on a second vehicle away from the coating booth. It will be understood that the operation of the first and second vehicles is synchronised such that they operate in tandem and contact the pipe surface only near the ends of the pipe so that again there is minimum risk of contact or interference with the applied coating. Conveniently the said vehicles are shuttled back and forth in a repeatable cycle which can be appropriately timed and coordinated with downstream pipe conveying or offloading devices to permit both vehicles to be returned for pipe end pick up whilst the next pipe in turn is entering the booth and undergoing coating. The invention permits an essentially continual and generally uninterrupted coating operation to be operated. The remotely operable support devices may include arms which may be rapidly deployed from a stand off position to a pipe contacting position by pivoting, swinging, sliding or like action. Therefore according to a first aspect of the present invention there is provided apparatus for the coating of pipes e.g. with a bituminous material, comprising a coating station, a pipe conveyor arranged in proximity to said coating station, means provided external to the coating station for holding at least a portion of one pipe on a support as it is conveyed into the coating station, means for rotating the conveyed pipe about its longitudinal axis, a plurality of mobile pipe carriers, and control means for synchronising the movement of the carriers with the conveyed pipe relative to said coating station. According to one embodiment of the invention there is provided a pipe conveyor whose final point of delivery is just short of a flood or curtain coating device provided within a coating station. A pair of parallel rails extends away from coating station to a pipe offloading area. Mobile carriers, positioned on the .rails adjacent to the coating station, stand ready to receive a coated pipe emerging from the coating station. Once coated, the pipe is conveyed away from the coating station firstly by one such carrier engaging the leading end of the emerging coated pipe and subsequently on other carrier cooperating in tandem with the first to support the trailing end of the pipe. The pipe would then be collected from the mobile carriers which are returned to their initial position ready to receive another pipe. The collection device may be a hoist, overhead gantry mounted crane, or other suitable lifting device adapted to minimise the risk of damage to the pipe coating. However preferably the carriers themselves are provided with off¬ loading lever mechanisms whereby the pipe may be laterally displaced from the carriers onto a storage facility or conveyor device. In a preferred embodiment the mobile carrier pipe supports are idler rollers mounted on hinged support arms. Said arms are curved in shape such that, when not held in contact with the pipe they may be positioned so as not to impede either the flow of coating material applied to the surface of the pipe, or the flow of excess coating material from the undersurface of the pipe. According to a second aspect of the present invention there is provided apparatus for the bituminous coating of rotating pipes comprising a coating delivery station, a static pipe conveyor terminating prior to said coating delivery station, a plurality of mobile pipe carriers, means for moving said pipe carriers relative to said coating delivery station and a catchment device positioned below said coating delivery station to recover coating material which does not adhere to the rotating pipes for recycling purposes. Thus further according to this invention there is provided a method of coating a series of pipes in a flood or curtain coating station comprising the steps of providing a pipe conveyor whose final point of delivery is just short of a flood or curtain coating device provided within said coating station, conveying a pipe in the direction of its longitudinal axis whilst rotating it about that axis and causing the one end of the pipe to project under the flood or curtain coating device whilst holding down a remote part of the pipe to stabilise the pipe, conveying the pipe further into the coating station by means of said conveyor and applying a coating by means of said coating device to coat said pipe, providing a plurality of mobile pipe carriers provided with deployable pipe supports and control means to operate a first and a second pipe carrier in a synchronised sequence related to the passage of the pipe through the coating station, actuating the first pipe carrier to provide support for the pipe as the pipe begins to emerge from the coating station, and after a SUBSTfTUTESHEET(RULE26) predetermined time delay actuating the second pipe carrier to provide support for the trailing end of the pipe, and operating the mobile carriers in tandem to carry the coated pipe away from the coating station. An embodiment of the present invention will now be described with reference to the following drawings, in which: Fig. 1 shows a side view of pipe transportation and bituminous coating apparatus in accordance with the present invention, with a pipe shown at the commencement of the coating process; Fig. 2 shows a side view of pipe transportation and bituminous coating apparatus in accordance with the present invention, with a pipe shown midway through the coating process; Fig. 3 shows a side view of pipe transportation and bituminous coating apparatus in accordance with the present invention, with a pipe shown at the end of the coating process; Fig. 4 shows a side view of pipe transportation and bituminous coating apparatus in accordance with the present invention, with a pipe shown in the "kick out" position; Fig. 5 shows a side view of a leading pipe carrier; Fig. 6 shows a side view of a trailing pipe carrier; Fig. 7 shows a front view of a trailing pipe carrier. Coating apparatus 5 provided by this invention includes a static conveyor 10 for transporting pipes 15, 15' in series to the entrance of a coating delivery station 20 whilst rotating them about their longitudinal axis. Mobile pipe carriers 25, 25", initially positioned adjacent to the static conveyor 10, are supported on rails 30. Said rails 30 lead from the static conveyor 10, past the coating delivery station, to a pipe unloading area 35. A collection pan 40 is provided below the delivery station 20 to collect any coating material which fails to adhere to the pipes. The leading portion 45 of pipe 15 is passed by the static conveyor 10 to the leading pipe carrier 25. Said leading pipe carrier is provided with a drive unit 50 with which to engage the leading portion 45 and maintain the rotation imparted to the pipe 15 by the static conveyor 10. Coating material is applied to the rotating pipe 15 as it passes the coating delivery station 20. The static conveyor 10 is provided with a hold down unit 55 (in the form of an overhead clamp adapted to make contact with the pipe by provision of means of roller devices) to prevent the leading portion 45 of the pipe 15 from pivoting downwards before it reaches the leading pipe carrier 25. Once the drive unit 50 is engaged, the leading pipe carrier 25 advances along the rails 30 and thus continues to move the pipe 15 past the coating delivery station 20. As the trailing portion 45' of the pipe 15 approaches the end of the static conveyor 10 it is supported by rollers 60 mounted on the trailing pipe carrier 25', thus allowing the pipe 15 to continue to rotate under the influence of the drive unit 50. Once the trailing pipe carrier 25' has received the trailing portion 45' of the pipe 15, it too advances along the rails 30 at substantially the same speed as the leading pipe carrier 25. The two carriers 25, 25' transport the rotating pipe 15 to the unloading area 35, whereupon it is ejected from the carriers 25, 25' by lever units 65 and 65' . The empty carriers 25, 25' then return along the rails 30 to their Original positions ready to receive the next pipe 15 ' from the static conveyor 10. A pipe carrier 25 (shown in Fig. 5) comprises a wheeled chassis 70 surmounted by a drive unit 50, driven support rollers 75 which serve to connect the drive unit 50 to the pipe 15, and a lever unit 65 to eject the pipe 15 from the carrier 25. The lever unit 65 is composed of a concave load bearing surface 80 connected to a support frame 85 by pins 90, the support frame 85 being attached in turn to the chassis 70. A hydraulic ram 95 is mounted between the load bearing surface 80 and the chassis 70. Extension of the ram 95 causes the load bearing surface 80 to rotate about the pins 90 and come into contact with the pipe 15 and, with further extension, tip the pipe 15 from the carrier 25. Referring to Figures 6 and 7 there is shown a trailing pipe carrier 25' comprising a wheeled chassis 100, a lever unit 65' and a pair of support arms 105. Said chassis 100 straddles the collection pan 40 when the carrier 25' is in its initial position adjacent to the static conveyor. Hence, during the coating operation, excess coating material may flow unimpeded from the undersurface of the pipe to the collection pan 40. Support arms 105 are connected by pins 110 to the chassis 100, and are surmounted by rollers 60. The arms 105 can be rotated about the pins 110 by the action of hydraulic rams 115 positioned between the arms 105 and the chassis 100. This enables the rollers 60 to be moved into and out of contact with the pipe 15 as shown in Figure 7. In use, the arms 105 and rollers 60 are only moved into contact with the pipe 15, in order to support it, as the trailing portion 45' approaches the end of the static conveyor 10. In this way the rollers 60 do not impede the passage of the majority of the pipe 15 past the coating delivery station. Furthermore, when not in contact with the pipe 15 the rollers 60 and arms 105 may be held in a position remote from the flow of coating material. It should be understood that foregoing illustrative description of the performance of the invention is given by way of example only, and the specific detail described in that illustrative embodiment is not intended to indicate that variants thereof are not possible. Indeed those skilled in this art will be well able to recognise that the specific form of the carriers can be varied according to choice. For example the first carrier may be actuated by contact with the pipe emerging from the coating station so that drive means for advancing the first carrier is not essential since forward motion is still being imparted to the pipe by the conveyor on the other side of the coating station. Obviously once the pipe leaves the conveyor the second carrier would need to be driven to continue the progression of the pipe out of the coating station. Similarly the specific drive mechanisms may be operated by a variety of systems as known in this art for other purposes. Moreover the carriers themselves need not be rail guided vehicles but could be soft tyred or track-laying vehicles. It will be recognised that the invention as herein disclosed provides a simple and relatively easily constructed solution to long-standing problems experienced in this art.

Claims: Claims : 1. Apparatus (5) for the coating of pipes (15, 15') sequentially in a flood coating station booth (20) including a catchment tray (40) for collecting excess coating for recycling, and pipe handling means adapted to contact a pipe (15) at predetermined times and in a predetermined manner permitting the pipe to be progressively advanced through the coating booth without the need for pipe supports passing under the flood coating which avoids the integrity of the applied coating becoming compromised by the pipe handling means and minimises the risk of the handling apparatus becoming fouled by coating spillage. 2. Apparatus according to claim 1 wherein said handling means includes a pipe feed mechanism (10) for introducing a pipe (15) lengthwise in the direction of its longitudinal axis to the coating booth whilst simultaneously applying an appropriate degree of rotation about that longitudinal axis, which mechanism has a pipe hold-down feature (55) whereby the leading end (45) of the pipe is permitted to project freely into the booth whilst another part of the pipe is restrained to avoid the pipe toppling into the booth due to lack of support at the leading end, and said handling means further includes at least first and second pipe end supports (60, 75) for picking up the coated pipe as it exits the coating booth. 3. Apparatus according to claim 2 wherein the first and second pipe end supports are provided on remote controlled vehicles (25, 25') which are independently operable to carry respectively the leading and trailing ends (45, 45') of the pipe as it emerges from the coating booth. 4. Apparatus according to claim 3 wherein the vehicles are rail guided. 5. Apparatus for the coating of pipes e.g. with a bituminous material, comprising a coating station (20) , a pipe conveyor (10) arranged in proximity to said coating station, means (55) provided external to the coating station for holding at least a portion of one pipe on a support as it is conveyed into the coating station, means for rotating the conveyed pipe about its longitudinal axis, a plurality of mobile pipe carriers (25, 25'), and control means for synchronising the movement of the carriers with the pipe carried thereon relative to said coating station. 6. Apparatus for the bituminous coating of rotating pipes comprising a coating delivery station (20) , a pipe conveyor (10) terminating prior to said coating delivery station, a plurality of mobile pipe carriers (25, 25') , means for moving said pipe carriers relative to said coating delivery station and a catchment device (40) positioned below said coating delivery station to recover coating material which does not adhere to the rotating pipes for recycling purposes. 7. A method of coating a series of pipes in a flood or curtain coating station comprising the steps of providing a pipe conveyor whose final point of delivery is just short of a flood or curtain coating device provided within said coating station, SUBSTITUTESHEET(RULE2® conveying a pipe in the direction of its longitudinal axis whilst rotating it about that axis and causing the one end of the pipe to project under the flood or curtain coating device whilst holding down a remote part of the pipe to stabilise the pipe, conveying the pipe further into the coating station by means of said conveyor and applying a coating by means of said coating device to coat said pipe, providing a plurality of mobile pipe carriers provided with deployable pipe supports and control means to operate a first and a second pipe carrier in a synchronised sequence related to the passage of the pipe through the coating station, actuating the first pipe carrier to provide support for the pipe as the pipe begins to emerge from the coating station, and after a predetermined time delay actuating the second pipe carrier to provide support for the trailing end of the pipe, and operating the mobile carriers in tandem to carry the coated pipe away from the coating station.

Inventors: LANE ALAN GREGORY, MULLEN DOUGLAS THOMAS, LANE, ALAN, GREGORY, MULLEN, DOUGLAS, THOMAS
Applicants: BREDERO PRICE SERVICES, BREDERO PRICE SERVICES LIMITED
Application year: 1996
Main classification: B05C5
IPC codes: B05B13, B28B21