Patent Application
20100330276
1. Field
The present disclosure relates generally to coating metal pipes, and more particularly to applying a uniform coating to the interior of relatively long tubular structures.
2. Description of the Related Art
Electroless Nickel Coating (“ENC”) is a nickel plating process for chemically applying nickel alloy deposits onto metallic substrates using an autocatalytic immersion process without the use of electrical current. ENC is often applied to relatively short tubular components (e.g., 10-foot lengths), by dipping individual lengths of pipe vertically into a sump tank or bath with vertically spaced spargers to inject solution into the long body of the pipe. This conventional coating technology suffers a number of limitations including the depth of the sump bath and correspondingly the height of the ceiling of the workspace into which the treated body must be positioned. Similarly, it is difficult and time consuming, thus inefficient, to secure the tubular substrates in position vertically while changing them and replenishing the solution between batches. A further disadvantage of the conventional vertical dipping process for coating long tubular structures is the limited ability to control the distribution of the nickel solute so as to permit it to plate long curved surfaces uniformly. In many applications it is important that the nickel coating be uniform. Further, for applications in oil-producing regions, it is often necessary to use much longer tubular goods (e.g., 40-foot lengths). Accordingly, it is desirable to find a way to consistently apply uniform electroless nickel coatings over very long curved surfaces.
Typically, ENC is only applied to shorter lengths of pup joints, because existing processes fail to efficiently coat full length tubular joints with consistent results. The prior art in the ENC industry has concentrated on teaching variations on vertically oriented bath tanks and pipes, which disadvantageously requires deep tanks and a tall building to plate long pipes. See, e.g., U.S. Pat. No. 4,262,044 and U.S. Pat. No. 6,245,389.
A system for applying a uniform electroless nickel coating to the interior of a bundle of long pipes, each pipe having an inlet end and an opposing outlet end may be summarized as including at least one distribution manifold, having a number of injection nozzles, for injecting a fluid into one end of each pipe in said bundle, said end in fluid communication with said interior; a reservoir having a supply of electroless nickel coating solution fluidly coupled to a pump that is fluidly coupled to said distribution manifold; and recirculation means for repeatedly returning said coating solution to said reservoir until the desired thickness of coating is reached. The solutes of the chemicals are replenished from time to time to ensure certain levels of concentration.
A method of using ENC to uniformly plate long tubular structures such as full length OCTG (Oil Country Tubular Goods) sections of pipe and well (surface and production) casing uniformly and efficiently may be summarized as including a nickel coating distributing evenly on an inner surface of long tubular structures (e.g., pipes) by generating circulations inside the pipes. According to certain aspects, pipes may be placed in a bath horizontally. According to certain aspects, multiple pipes may be arranged in bundles and the bundles placed in the bath horizontally. According to certain such aspects, multiple pipes may be coated simultaneously. According to at least one aspect, pipes may be coated efficiently and uniformly at decreased cost.
In the drawings, identical reference numbers identify similar elements or acts. The sizes and relative positions of elements in the drawings are not necessarily drawn to scale. For example, the shapes of various elements and angles are not drawn to scale, and some of these elements are arbitrarily enlarged and positioned to improve drawing legibility. Further, the particular shapes of the elements as drawn, are not intended to convey any information regarding the actual shape of the particular elements, and have been solely selected for ease of recognition in the drawings.
In the following description, certain specific details are set forth in order to provide a thorough understanding of various disclosed embodiments. However, one skilled in the relevant art will recognize that embodiments may be practiced without one or more of these specific details, or with other methods, components, materials, etc. In other instances, well-known formulations, process steps, and structures associated with ENC have not been shown or described in detail to avoid unnecessarily obscuring descriptions of the embodiments.
Unless the context requires otherwise, throughout the specification and claims which follow, the word “comprise” and variations thereof, such as, “comprises” and “comprising” are to be construed in an open, inclusive sense, which is as “including, but not limited to.”
Reference throughout this specification to “one embodiment” or “an embodiment” means that a particular feature, structure or characteristic described in connection with the embodiment is included in at least one embodiment. Thus, the appearances of the phrases “in one embodiment” or “in an embodiment” in various places throughout this specification are not necessarily all referring to the same embodiment. Furthermore, the particular features, structures, or characteristics may be combined in any suitable manner in one or more embodiments. Reference herein is made to
The term “tubulars” as used herein refers to tubular structures and includes tubing or piping having circular, rectangular, or other cross-sectional shapes and having lengths as appropriate. Lengths may, for example, extend to at least 40 feet or greater. Tubular structures, tubing, tubes, piping or pipes, including singular forms thereof, may be used interchangeably herein and in the claims.
As used in this specification and the appended claims, the singular forms “a,” “an,” and “the” include plural referents unless the content clearly dictates otherwise. It should also be noted that the term “or” is generally employed in its sense including “and/or” unless the content clearly dictates otherwise.
The headings and Abstract of the Disclosure provided herein are for convenience only and do not interpret the scope or meaning of the embodiments.
A number of embodiments of apparatus, systems and methods for Electroless Nickel Coating (ENC) are described herein. The ENC apparatus and systems perform ENC on pipes or tubing, particularly oil country pipes or tubing. As disclosed herein, the pipes or tubing may be advantageously positioned horizontally during ENC. Such horizontal positioning may advantageously allow nickel coating of lengths of pipe or tubing substantially greater than is allowed by apparatus, systems and methods commonly used for ENC, during which pipes or tubing are positioned vertically. Further, ENC by the apparatus, systems and methods disclosed herein may provide uniform nickel coating on curved surfaces of the pipes or tubing that is more uniform than can be provided by commonly used approaches to ENC.
Movement of bundles 110 of pipes 112 throughout the tank farm may be by any suitable means, for example without limitation clamp/strap/hook assembly 118. Transport of bundle 110 of pipes 112 via assembly 118 to any location within the tank farm may utilize any available overhead crane or forklift or similar means for moving bundle 110. Each tank in a treatment section of a farm contains a solution suitable for a given step in the ENC process. For cost and time efficiency, tubes 112 are preferably assembled into bundles 110 as discussed above. In the particular embodiment shown in
At least one tank contains a cleaning solution 115, for example an acid wash suitable to effect a preliminary macro cleaning of each tube 112 in bundle 110. Bundle 110 may preferably be dipped into cleaning solution 115 two or more times.
Another tank contains an appropriate rinse solution 120, for example water or a solution of a suitable detergent in water. Once the tubes 112 are sufficiently acid cleaned in solution 115 for the particular coating specified, the tubes 112 are moved to a tank containing the rinse solution 120. The tubes 112 may typically be immersed in the rinse solution 120. In certain embodiments the tubes may preferably be immersed therein two or more times, as necessary.
A further tank contains an etching solution 125 appropriate for the particular coating process to be used in ENC. Once tubes 112 are sufficiently rinsed, the tubes 112 are moved to a tank containing the etching solution 125 in which the tubes 112 are immersed. Immersion of tubes 112 into etching solution 125 may be complete or partial, depending on the degree of etching required for a particular coating.
Yet a further tank may contain a second rinse solution 130, for example water or a solution of a suitable detergent in water. Once the tubes 112 are sufficiently etched for the coating specified, the tubes 112 may be moved to and immersed in a tank containing an appropriate second rinse solution 130. The second rinse solution 130 may, for example, take the form of water or a solution of a suitable detergent in water. The final rinse may preferably be performed in purified water, such as may be obtained by reverse osmosis treatment. Each of these acts carried out prior to the coating step(s) may typically be completed at room temperature (e.g., 60-70° F.).
The final tank according to the embodiment illustrated in
Cleaned, etched, and rinsed tubes 112 in bundle 110 are then ready for electroless nickel coating (ENC), the precise formulation of which coating solution 150 (preferably heated to a temperature in the range 80 to 99 degrees C.) depends upon the desired coating properties. The formulation of coating solution 150 depends on the desired properties of the coating to be applied to tubes 112. In one embodiment, coating solution 150 is preferably heated to a temperature ranging between 80° C. and 99° C. In certain embodiments, tubulars need only be coated on their internal surfaces. In preparation for coating, external surfaces of such tubulars may be protected by wrapping in any suitable covering, e.g., a polymer tape or any suitable paint such as epoxy). The covering may prevent the exterior surfaces of the tubulars from reacting to or with the nickel ions in coating solution 150.
Once any protective steps have been completed, the tubes 112, individually or in bundles 110 as appropriate, are moved by any suitable means into a tank containing an appropriate nickel alloy coating solution 150. The nickel solute concentration in the coating solution 150 is selected to achieve the desired thickness of coating of the surface area to be plated. In certain embodiments, the nickel alloy coating solution 150 may have a specific gravity of 1.14 and a viscosity of 0). In certain embodiments, the concentration of nickel solution in the coating solution 150 is selected to achieve a coating rate of 0.005 mm/hour-0.015 mm/hour on the surfaces of the tube(s) to be coated. In certain embodiments, the temperature of the coating solution 150 ranges between 80° C. and 95° C. In certain embodiments the concentration of nickel solute in the coating solution 150 is 30% or less. The temperature and chemical formulation of the coating solution 150 are established according to the expected end use of tube 112 and the coating properties required for that use. Prior to immersing tube bundle 110 into coating solution 150, hoses 170 connected to distribution manifold 180 are fluidly coupled, by any suitable means, to either end of each tube 112 in bundle 110.
According to one embodiment of the apparatus and system disclosed herein, each hose 170 is inserted into an end of each tube 112. Distribution manifold 180 is fluidly coupled via input line 181 to a supply (typically pressurized, however it could be gravitationally fed) of nickel alloy solution corresponding to coating solution 150. The supply may be fed gravitationally or further pressurized. The coating solution 150 may be supplied from or circulated through a reservoir 185. The coating solution 150 may be circulated through the tubes 112 and tank 105 by being steadily driven by any suitable pump (not shown) fluidly coupled to reservoir 185 and operated at a flow rate sufficient to circulate coating solution 150 through tank 105. Circulation through the system may be at a rate of 15 to 30 times per hour, thereby keeping the coating solution 150 well mixed and sufficiently uniform in concentration, thus helping to provide an even coating on the relatively long curved surfaces of the tubes 112 being plated. Circulation of the coating solution 150 within the system may occur by gentle backwash or recirculation. In certain embodiments, flow of coating solution 150 within the tubes 112 during coating is preferably laminar flow rather than turbulent flow to more uniformly provide coating solution to the surfaces to be coated. In certain further embodiments, bundle 110 may be gently rotated, e.g., driven by any suitable rotisserie-like motor means, to more uniformly provide coating solution to the interior surface of each tube 112. The particular flow rate selected depends upon the specifications of the coating type and thickness. The deposition rate of a given nickel alloy is influenced by a number of factors including the nozzle pressure at hose 170 and the related velocity with which the nickel alloy coating solution 150 passes over the interior surface of each tube 112.
Upon completion of coating and depletion of solute from coating solution 150, bundle 110 of the now nickel alloy-coated tubes 112 is removed from coating solution 150 and allowed to cool to near room temperature. The bundle 110 of tubes 112 is then again rinsed in pure water, typically dipped three times for a few seconds each time. According to one embodiment, the tubes are then exposed to the air at room temperature for approximately 1 minute for passivation. Passivation refers to a process of making the coating “passive” by spontaneous formation of a hard surface film, usually an oxide or nitride, a few atoms thick, on the surface of the coated and rinsed tubes 112 in bundle 110. Passivation seals cracks or pinholes in the coating, which helps maintain surface hardness, improves surface glare, and increases the life span of the surface coating.
According to another embodiment, where additional surface coating hardness is required, bundle 110 of tubes 112, after coating, is subjected to heat treatment via baking. In certain embodiments, baking of the tubes 112 is performed at a temperature between 300 and 400° C. for 1 to 3 hours. In certain embodiments, the temperature and time may be varied inversely. Upon completion of baking, the bundle 110 of tubes 112 is allowed to cool at room temperature (in air) to permit the coating bonds to stabilize and tube surfaces to anneal, thus increasing the hardness of the coating. It is to be understood that a person of ordinary skill in the art of heat treatment would know to set the particular temperature and time in accordance with the specified hardness required in the tubes 112 in use. The tubes 112 are typically cleaned (e.g., rinsed) one final time before packing for shipping.
Reservoir 205 may be any suitable shape, dimensions and capacity applicable to deliver the specified coating solution to the particular number of tubes 112 comprising the particular bundle 110 used in a particular application of embodiments of the system disclosed herein. Similarly, filler nozzles 210 are provided in sufficient number and of a size that corresponds to the shape and dimensions of the tubulars being coated. Further, filler nozzles 210 may be constructed from a material and in a manner providing enough strength to permit apparatus 200 to support an end of bundle 110. However, when used with alternate means for supporting the ends of a bundle (e.g. using clamps 111), filler nozzles 210 may be constructed from a light weight material (e.g. stubs of hose 170) that directs solution into each tube 112 without providing means to either maintain or lift a bundle of tubes of any size.
Regardless of the capacity of distribution manifold apparatus 200 to maintain the relative position of tubes 112 in a bundle 110, according to a preferred embodiment of the apparatus, advantageously there is provided a removable end cap 220 that is removably fastened (by any suitable means) to the opposing end of reservoir 205. Such permits periodic cleaning and allows an operator to leave apparatus 200 in place while changing the solution being supplied to bundle 110. Whether threaded, slip fit and bolted or riveted—or otherwise sealed to one end of reservoir 205, end cap 220 (having any suitable inlet 225 provided therein) permits the rapid, seamless change out of supply lines both feeding and draining cleaning or treatment solutions to, or from, bundle 110.
According to one embodiment of distribution manifold apparatus 200 that both maintains the shape of bundle 110 and permits an operator to move that bundle throughout a tank farm, support member 230 both facilitates the installation of apparatus 200 into each end of a bundle 110 and permits that bundle to be secured to any suitable lifting means.
According to the embodiment illustrated in
Although the disclosure describes and illustrates various embodiments, it is to be understood that these particular embodiments are provided without limitation. As a direct result of this disclosure, variations and modifications will now occur to those skilled in the art of Electroless Nickel Coating for longer tubulars. The various embodiments described above can be combined to provide further embodiments. To the extent that they are not inconsistent with the specific teachings and definitions herein, all commonly assigned U.S. patents, U.S. patent application publications, U.S. patent applications, referred to in this specification and/or listed in the Application Data Sheet are incorporated herein by reference, in their entirety. Aspects of the embodiments can be modified, if necessary, to employ structures and concepts of the various patents and applications to provide yet further embodiments.
These and other changes can be made to the embodiments in light of the above-detailed description. In general, in the following claims, the terms used should not be construed to limit the claims to the specific embodiments disclosed in the specification and the claims, but should be construed to include all possible embodiments along with the full scope of equivalents to which such claims are entitled. Accordingly, the claims are not to be construed as being limited by the disclosure.
This application claims benefit under 35 U.S.C. 119(e) to U.S. provisional patent application Ser. No. 61/220,997 filed Jun. 26, 2009 which is incorporated herein by reference in its entirety.
| Number | Date | Country | |
|---|---|---|---|
| 61220997 | Jun 2009 | US |
