This application claims priority to and the benefit of United States Patent

Application Serial Number 61/504,279 filed July 4, 2011, the subject matter of which is incorporated herein by reference.

FIELD

[0001]

The invention relates to a device and a method for vibrationally finishing an impinged concrete coating on a pipe, and a pipe having a smoothened concrete coating.

BACKGROUND

[0002] Typically, an impingement process is used for offshore concrete coating of a pipe. The process involves batched material passing through two large rubberized rollers at high speed to build up the required concrete thickness on the pipe. The impingement process creates a surface which is uneven (non-uniform), rough and undulating due to a number of reasons, including layer overlap, variations in the mass of the feed delivered to the rollers, rebound and surface fall- off.

[0003] The non-uniform surface of the concrete appears porous, along with a reduced average density of the concrete in the outer layers of the coating.

Decreasing the variation in surface profile can allow for a reduction in concrete thickness or the application of concrete which has a higher density - either the mass of concrete or the amount of iron ore in the concrete can be decreased to obtain the desired negative buoyancies.

[0004] Also, when phi tapes measuring systems are used to measure the diameter of such non-uniform pipes, the measurements are essentially peak-to- peak and therefore the diameter is greater than the actual diameter. Decreasing the variation in the profile of the surface can provide more accurate determination of pipe diameter and therefore better buoyancy estimates.

[0005] In addition to the above, the non-uniform surface formed from an impinged concrete coated pipe leads to dust generation during the process of laying the pipe. The impinged concrete surfaces shed a significant amount of fine concrete material because the outer layers are friable. According to a marketing survey, it costs lay barge operators about $2 million annually to remove detritus generated by impinged concrete. Concrete which has a smoother and denser surface will generate less detritus and reduce disposal costs for lay barge operators.

[0006] The smoothening of pipes can have a tertiary benefit which is the reduction of the coefficient of friction between the pipe and the seabed. In some instances, problems have been reported when the friction between the pipes and the seabed can lead to significant dust generation.

[0007] Hence, there is a need in the art for a process for finishing the concrete coating surface on a pipe to obtain a smoothened coating. The finishing of an impinged concrete coating can address a number of concerns, as noted above. In addition, there is a need in the art for a device for carrying out the process to finish and provide a smoothened concrete coated pipe.

SUMMARY OF THE INVENTION

[0008] In one aspect, the invention relates to a pipe coating finishing device comprising :

- one or more frames having a first arm and a second arm;

- a scraper coupled to a first arm for engaging a pipe to remove material in excess of a maximum pipe diameter; and

- a vibrating plate coupled to a second arm for compacting an impinged concrete coating on the pipe. [0009] In another aspect the invention relates to a process for finishing an impinged concrete coating on a pipe with a device having a frame containing a first arm, a second arm, a scraper coupled to a first arm and a vibrating plate coupled to a second arm, the process comprising the steps of:

- scrapping material in excess of a maximum coated pipe diameter; and

- vibrational^ compacting a surface of the impinged concrete coated pipe to form a smoothened concrete coated pipe.

In a further aspect the invention relates to a concrete coated pipe having a pipe and a concrete coating on the pipe; and wherein the concrete coated pipe has an average depth of indentation measured on the coating of ≤5 mm .

BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Reference will now be made, by way of example, to the accompanying drawings which show example embodiments of the present application, and in which :

[0011] Figure 1 shows a front elevational schematic view of an embodiment of the device according to the invention;

[0012] Figure 2 shows a perspective schematic view from the vibrating plate side of an embodiment of the device according to the invention;

[0013] Figure 3 shows a perspective view from the scraper side of an embodiment of the device according to the invention;

[0014] Figure 4 shows a top view of an embodiment of the device according to the invention;

[0015] Figure 5 shows a side elevational view of an embodiment of the device according to the invention;

[0016] Figure 6 shows a perspective view of a set-up of a vibrational finishing plate device according to another embodiment of the invention; [0017] Figure 7 shows a picture of a impinged concrete coated pipe undergoing a vibrationally finishing plate process according to the invention;

[0018] Figure 8 shows an electric vibrator having eccentric weights used in an embodiment according to the invention; [0019] Figure 9 shows a close-up picture of a pipe showing the surface of an impinged concrete coated pipe along with a vibrationally finished concrete coated pipe after undergoing the process according to an embodiment of the invention;

[0020] Figure 10 shows another close-up picture of a pipe showing the surface of an impinged concrete coated pipe along with a vibrationally finished concrete coated pipe after undergoing the process according to an embodiment of the invention;

[0021] Figure 11 shows a picture of a surface of a vibrationally finishing concrete coated pipe after undergoing through the process according to the invention; [0022] Figure 12 shows the iron ore sieve analysis used in coating the pipe in accordance with the process of the invention;

[0023] Figure 13 discloses the profile of test pipes after finishing with a vibrating finishing plate (VFP) device used in accordance with the process of the invention;

[0024] Figure 14 discloses the outer diameter (OD) profile of pipe M lbefore and after undergoing the process according to the invention;

[0025] Figure 15 discloses the outer diameter (OD) profile of pipe Gl before and after undergoing the process according to the invention;

[0026] Figure 16 discloses the densities and thickness of various pipes having an impinged concrete coating;

[0027] Figure 17 a front elevational schematic view of another embodiment of the device according to the invention; [0028] Figure 18 a top elevational schematic view of another embodiment of the device according to the invention;

[0029] Figure 19 a front elevational schematic view of a further embodiment of the device according to the invention;

[0030] Figure 20 a front elevational schematic view of another further embodiment of the device according to the invention;

[0031] Similar reference numerals may have been used in different figures to denote similar components.

DESCRIPTION

[0032] As discussed above, the invention relates to a pipe coating finishing device (1), a process for finishing an impinged concrete coating (32) on a pipe (12) with the pipe coating finishing device (1), and a pipe (12) having a smoothened concrete coating.

[0033] Figures 1-7 show a pipe coating finishing device (1) that contains a frame (2) having a first arm (4) and a second arm (6). Coupled to the first arm (4) at the pipe end of the first arm (10) is a scraper (8), which is used to remove any impinged concrete coating material that exceeds a pre-set maximum concrete coated pipe diameter. While the second arm (6) is coupled to a vibrating plate (14) at the pipe end of the second arm (16), for compacting an impinged concrete coating on the pipe (32). As shown in figures 1-5, both the first arm (4) and the second arm (6) are coupled to a single frame (2) structure. However, separate frame structures can be used (as shown in figures 16-20), where a first arm (4) is coupled to a first frame structure (not shown) and the second arm (6) is coupled to a second frame (2) structure (shown in figures 16-20). As described herein, such embodiments are intended to be covered by the frame (2) and the first arm (4) and the second arm (6), disclosed herein. [0034] The vibrating plate (14) used in the device (1) is able to vibrate at sufficiently high frequency and apply sufficient pressure to compact the impinged concrete coating on the pipe (32). In one embodiment of the invention, the vibrating plate (14), as disclosed in the embodiment shown in the figures, has a convex surface that faces away from the pipe and a concave surface (22) that faces the impinged concrete coated pipe (32). In a further embodiment of the invention, the concave surface (22) of the vibrating plate (14) has a radius of curvature to allow nearly the entire concave surface (22) to contact the outer surface of the impinged concrete coated pipe (32). Such a concave structure can assist in uniformly compacting and finishing the impinged concrete coating on the pipe.

[0035] In one embodiment of the invention, the vibrating plate (14) is provided with a vibrator (18) (Figures 1, 2, 8 and 16-20), which permits the vibrating plate (14) to vibrate at a desired frequency. In a further embodiment according to the invention, the vibrating plate (14) vibrates at a frequency from about 1500 to about 18000 vpm . In another embodiment according to the invention, the vibrating plate vibrates at a frequency from about 3500 to about 12000 vpm . In a still further embodiment, the vibrating plate (14) vibrates at a frequency from about 6500 to about 9000 vpm . In another embodiment, the vibrating plate (14) vibrates at a frequency of about 3000 vpm .

[0036] In an embodiment according to the invention, the vibrating plate (14) applies a static pressure on the impinged concrete coated pipe (32) to compact and provide finishing to the concrete coating. In one embodiment, pressure can be applied by using weights (34) on the vibrating plate (14) (figures 19 and 20). In another embodiment, pressure can be used by connecting the vibrating plate (14) to a hydraulic system (figures 16-18). The amount of pressure applied can also vary depending upon the properties of the coated concrete and the vibrating plate (14). In one embodiment, the amount of static thrust force applied ranged from about 3 to about 200 psi. In another embodiment, the amount of static thrust force applied ranged from about 75 to about 150 psi, and values in between. In a still further embodiment, the amount of down force applied using about 3 to 6 bar of pressure ranged from about 4 to 12 kN .

[0037] As the vibrating plate (14) vibrates, the impinged concrete coating is compacted to obtain a smoothened surface. The size of the vibrating plate can vary depending upon pipe and the desired process. In one embodiment, for example and without limitation, the width of the vibrating plate (14) is such that any given area of the impinged concrete coating is compacted and finished at least twice by the vibrating plate (14). Other embodiments, where compacting and finishing on any given area is performed multiple times, such as, for example and without limitation, three, four, five or more, by the vibrating plate are also encompassed by the present invention. The number of times, compacting and finishing on any given area on the concrete coated pipe is performed can depend on the pipe dimensions, pipe line speed, pipe rotation. In one embodiment, for example, where the pipe has an outer diameter (OD) of 914.4mm and 23 mm wall thickness, and where the concrete coating thickness was 75 mm, the linear speed of the pipe was 7.5 m/min and rotation was 20.69 rpm . Based on this, it was determined that the coating surface rotates at 1.49 revolutions under the area of the finishing plate.

[0038] During the compacting and finishing process, to avoid the edges of the vibrating plate from digging into the compacted and finished concrete coating, the edges of the vibrator plates are raised (20) (see Fig. 1 and 16-20). This provides a vibrator plate (14) with smoothened edges and also assists in producing a smoothened concrete coated pipe. Other variations of smoothened edges, such as, for example and without limitation, rounded edges, are also encompassed by the present invention. [0039] The scraper (8) and the vibrating plate (14) are positioned on the pipe (12) to allow the scraper (8) to first contact the impinged concrete coating (32) on the pipe (12), so as to remove concrete that is in excess of a maximum concrete coated diameter. Subsequently, after an area of the impinged concrete coating (32) on the pipe (12) undergoes scrapping, it then contacts the vibrating plate (14) for smoothening and finishing the concrete coating on the pipe. The leading scraper takes the larger surface undulations and particles out, and the VFP which follows is able to smooth this pre-conditioned surface.

[0040] The positioning of the scraper (8) and the vibrating plate (14) on the impinged concrete coated pipe (32) can be such that both the scraper (8) and the vibrating plate (14) are positioned in-line along the length of the pipe (12). One possible way to achieve this, is to have the scrapper and the vibrating plates on separate frames, such as embodied in Figures 16-20. However, the impinged concrete coating and finishing process can also be carried out concurrently, so as to allow impingement of the pipe prior to scrapping and finishing the concrete coated pipe. In such a process, the pipe is rotated and moved along the length of the pipe while being impinged by a concrete coating. In such an embodiment, the vibrating plate (14) and the scraper (8) are positioned in-line along an axis perpendicular to the longitudinal axis of the pipe (12). Therefore, as the pipe (12) is impinged with a concrete coating, rotated and moved along the length of the pipe (12), it is also scrapped and finished to obtain a smoothened concrete coating on the pipe (12) (Figures 1-6).

[0041] In addition to the above and as shown in the figures, the scraper (8) and the vibrating plate (14) can be positioned on the pipe (12) to be adjacent to each other, as shown in Figures 1-7. In one embodiment, the scraper (8) is positioned below and the vibrating plate (14) is positioned above a plane

diametrically dissecting the pipe (12). The plane that diametrically dissects the pipe (12) can lie normal to the ground surface. In a further embodiment, the scraper (8) and the vibrating plate (12) are symmetrically positioned about the plane diametrically dissecting the pipe (12). In the embodiments disclosed in the figures, the scraper (8) and vibrating plate (14) are positioned at an angle of about 30° measured from the pipe centre. However, other angles, such as about 20°, 25°, 35° or 40° may also be considered acceptable. While in the embodiments disclosed in Figures 16-20, the vibrating plate (14) and/or the scrapper (not shown) can lie in the plane that diametrically dissects the pipe (12), with the plane being normal to the ground surface. [0042] The step of impinging a concrete coating on the pipe (12) is not particularly limited. In one embodiment, for example and without limitation, impingement of the concrete coating on the pipe (12) is carried out by use of impingement rollers. In the embodiment disclosed above, where coating, scrapping and finishing is carried out concurrently, the impingement rollers can be positioned adjacent to the vibrating plate and/or the scraper.

[0043] The scraper (8) used in accordance with the invention should be able to remove excess impinged concrete coating on the pipe (12) without damaging the concrete coating. In one embodiment, for example, the scraper (8) is provided with a first end plate (24), a second end plate (26) and a plurality of rods (28) connecting the first end plate (24) to the second end plate (26). The plurality of rods (28) extending from the first end plate (24) to the second end plate (26) can be positioned to extend along the length of the pipe (12), to allow scrapping the excess impinged concrete coating on the pipe (12), as the pipe (12) rotates and moves along the length of the pipe (12). Moreover, the plurality of rods (28) can be so arranged that they together define a curved plane having a radius of curvature equal to the set maximum radius of the coated pipe (12).

[0044] The above-noted concurrent steps of impinging the concrete coating, scrapping the excess concrete coating and finishing the concrete coating, the process can be carried out a surface speed of the pipe (12) sufficient to adequately smoothen and finish the pipe (12). In one embodiment, the surface speed of the pipe is from about 50 to about 100 meters/min, and values in between, such as, about 60, about 70, about 75 and about 80 meters/min.

[0045] In a further embodiment in accordance with the specification, water can be applied during the process for finishing an impinged concrete coating on a pipe. The application of water can help with the scrapping step, the vibrational^ finishing step, or both. The rate of water application in the process can vary. In one embodiment, for example, the rate of water application ranged from about 0.030 to 1.000 L/m ² . In another embodiment, the rate of water application ranged from, for example, about 0.047 to 0.071 LJm ² . [0046] Using the device and method disclosed herein, concrete coated pipes having a smoothened profile were obtained. To evaluate the smoothness of the coating on the pipe, the average depth of indentation on the concrete coated pipes were measured. In one embodiment, for example, the average depth of the indentation measured on the coating was below 5 mm . In another embodiment, the average depth of the indentation measured on the coating ranged from, for example, about 2.5 to 4.96 mm. In a further embodiment, the average depth of the indentation measured on the coating ranged from about 3% to about 6.5%.

[0047] The device and process according to the invention leads to a concrete coated pipe having a smoothened finished surface, as shown in figures 7 and 9-11. In addition, the amount of detritus generated can be significantly lowered, which can address some of the health and safety hazards associated with the impinged concrete coated pipes in present use. In one embodiment, for example, the pipes obtained using the process disclosed herein, generated about 200, 300, 400, 500%, 600% or 700%, and values in between, less detritus than that generated using an impinged concrete coated pipe.

DESCRIPTION OF EXAMPLE EMBODIMENTS

[0048] The application will be described by way of a non-limiting example to disclose the process of obtaining a smoothened and finished concrete-coated pipe.

[0049] Materials and Methods

[0050] The pipes were 44 inches in diameter and had a wall thickness of 23.3 mm. The anticorrosion coating was 6 mm (modified) asphalt. Plastic spacers (65 mm) positioned the 8 mm rebar cage in the middle third of the 110 mm concrete coating. Eight strands of fibrillated polypropylene twine were wrapped around the pipe to restrain the concrete and prevent disbondment or fall-off. The twine stands are typically positioned within the first 10 mm of the concrete surface and approximately 5 kg of tension was applied on each strand of twine.

[0051] A concrete mixture with a target density of 3400 kg/m ³ and containing 550 kg/m ³ Portland cement was used. The range of moisture content acceptable for coating was 4.5 to 5.1%. The Portland cement was supplied by Norcem AS Norway, the magnetite from Minelco AB Sweden. The sieve analysis data for the aggregate is shown in Figure 12.

[0052] For the diameter of pipe and concrete thickness used in this test program, the coating time and surface speed selected were 165 seconds and 72 meters/minute, respectively.

[0053] The vibrating finishing plate used in this test program was 540 mm wide x 500 mm long. The width of the plate was based on the design criteria that any given area of the concrete surface would be compacted and finished twice by the vibrating finishing plate (VFP). Two Dynapac ER 305 electric vibrators were used (Figure 8). Alternately, other vibrators such as VIBCO US-450T-230V can also be used. The vibrators were mounted parallel to each other on the plate at opposite ends of the plate (Figure 6). The rotors in the vibrators operated at a fixed speed of 3000 rpm and the internal weights (Figure 8) were set for the maximum force of 3000 Newtons. The vibrators were electrically connected such that the rotors inside the vibrator were counter rotating with respect to each other - one shaft rotated clockwise and the other anti-clockwise - this produced a reciprocating motion that was predominantly normal to the surface of the concrete. A 100 mm diameter pneumatic cylinder was used to apply a static pressure to the plate. For the tests in this program the maximum pressure of 101.5 psi was used. The estimated static thrust force on the plate was 3 psi. The vibrating finishing plate was mounted just in front of the impingement rollers and in line with the scraper. The scraper and VFP contacted the pipe at approximately 28° before and after top-dead-center, respectively (Figures 6 and 7). [0054] The VFP was evaluated by first coating the pipe without the VFP and measuring the outside diameter of the pipe via the optical OD measuring system. After the pipe was coated, manual measurements were immediately taken and recorded. The pipe was repositioned and passed through the HeviCote system again with a normal production surface speed of 72 meters/min . but with the VFP on the pipe running with maximum pressure and amplitude. Again, OD

measurements were taken by the optical system and manually.

[0055] Profile analysis was performed on the smoothed surface after hardening by measuring the depth of the surface relative to a 1.95 meter long aluminum straight edge (Figure 13) every 10 cm . The straight edge was moved along the length of the pipe until the full length was profiled.

[0056] Results

[0057] Figures 14 and 15 show the OD profiles before and after the VFP.

According to manual measurements, the OD was reduced 3.2 and 1.4 mm for pipes M l and Gl, respectively. For measurements by the optical system, the OD was reduced by 1.9 and 1.3 mm.

[0058] The profile of the surface for both pipes after finishing and curing is given in Figure 13. Due to the weak nature of uncured concrete and the loss of surface moisture it was not possible to determine a profile of the freshly impinged pipe before exposure to the VFP. As reference and for comparison, the profile for various pipes manufactured is given in Figure 16. The average variation in depth of unfinished impinged concrete according to profile measurements is generally 4-5 mm and for finished pipes about 3.4 mm (~ 1 mm reduction).

[0059] Theoretical analysis using the profile data for unfinished and finished pipes indicates that this variation reduces the overall density of the concrete on the pipe and requires that concrete with a higher density be applied. Figure 11 illustrates the effect of finishing on the density of the (applied) concrete required to meet the target density on the pipe. Assuming a 50 mm concrete coating thickness and a target density of 3044 kg/m ³ , the density of the applied concrete for unfinished pipes must be at least 3300 kg/m ³ , and for finished pipe the density needs to be a minimum of 3167 kg/m ³ . Approximately 9% less iron ore (4800 kg/m ³ density) is needed per metric ton of concrete when the density is decreased from 3300 to 3167 kg/m ³ .

[0060] A trial to mimic the handling a pipe will experience on a typical laybarge firing line was performed. This was done by repeatedly running the test pipes over a fixed set of rollers for a total of 20 passes. One pass is considered a movement of lm in the forward direction. The dust generated was collected by two sources, after the 20 passes. The smaller dust particles were sucked up via a large industrial vacuum whilst the heavier particles which were not captured by the vacuum fell onto a collection plate. The two dust collection sources were weighted and analyzed separately. Four tests were conducted on each pipe at the 12, 3, 6 and 9 o'clock positions on the pipe, VFP and impinged pipe, gathering a total of 80 passes, 20 passes per individual test. Two pipes were used, one impinged pipe which acted as the "control pipe", and one VFP pipe. The control pipe provided a baseline to compare the dust levels generated by the VFP pipe. Dust levels utilizing the VFP decreased 471% compared to the impinged concrete pipe. This is a significant reduction in dust compared to normal impinged concrete and occurred in all gradation spectrums.

[0061] The trials conducted demonstrated that the VFP can significantly improve the uniformity of the surface and thereby reduce the thickness of the concrete coating, without loss of material.

[0062] Certain adaptations and modifications of the described embodiments can be made. Therefore, the above discussed embodiments are considered to be illustrative and not restrictive.