CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority to U.S. Provisional Application No. 63/405,174, filed on September 9, 2022. The entire disclosure is incorporated herein by reference.

BACKGROUND OF THE INVENTION

Field of the Invention

[0002] The present invention relates to a method of repairing a coating, such as repairing a coating applied over a metal pipe and a kit for repairing a coating applied over a metal pipe. Description of Related Art

[0003] Due to the inherent risk of transporting oil, natural gas and other natural gas and/or liquids, the metal pipes used to transport these products require additional corrosion protection to ensure their safety. Pipeline pipe for oil and gas may be about 4 to 42 inches in diameter, and thus, circumference may be about 12 to about 130 inches. Pipe for water and other applications may be up to about 80 inches in diameter.

[0004] Sometimes pipes, both for oil and gas and also for water pipes, develop corrosion that corrodes a significant portion of the pipes thickness - i.e., from about 20% to 75%. Additionally, sometimes during the course of its use, a pipe can develop a dent on its side. This corrosion or dent can affect the amount of internal pressure a pipe can safely handle.

[0005] There are different methods of repairing these anomalies - removing the pipe and replacing it, welding a piece of steel overtop, winding with metal spring and securing it, and also, over the last 15 - 20 years, the use of composite repair. The composite repair uses fiberglass (and/or Kevlar fiber and/or carbon fiber) cured with either two-part liquid epoxy or polyurethane. With liquid epoxy, it is necessary to mix the liquid resin (A side) with the liquid curing agent (B side), and then spreading the mixture onto a fiberglass sheet or roving is required. The liquid epoxy will cure shortly after its mixture, such as 24 hours or less. The liquid epoxy has to be mixed and coated onto the fiberglass at the jobsite.

[0006] In the United States, oil and gas pipelines (on land) generally utilize a dual corrosion protection system: a specialized epoxy coating provides the main protection, while as an additional measure the pipes have electrical cathodic protection (“CP”). A simple explanation of CP is that metal can only rust when it gives off electrons. If electricity is run through the metal it is unable to rust. A CP system is installed on the oil and gas pipelines to prevent rust. [0007] The specialized epoxy coating is commonly known as fusion bonded epoxy (“FBE”). FBE is typically applied to a pipeline as a powder composed primarily of solid epoxy resin and a curing package, such as dicyandiamide with an accelerator. The dicyandiamide together with the accelerator is known as the ‘curing agent’ or ‘curing agent package.’

[0008] The FBE is a powder epoxy coating, and for it to form a film it needs to melt, flow, and cure in a continuous film. Due to inherent issues in the coating process, a small hole in the coating can form from insufficient flow of the FBE coating before it cures.

[0009] To ensure the protection of the steel pipe from corrosion, it is necessary to repair these small holes at the pipe coating plant. In the recent past an “Epoxy Melt Stick” composed of solid epoxy would be melted onto these holes and allowed to cool and solidify. However, it was found that this process did not allow complete cure of the epoxy, and it gave insufficient corrosion protection. As such, the use of this process has been significantly reduced.

[0010] Currently, the two part liquid epoxy is mixed and applied to the steel pipe to repair the hole. Sometimes the area of the pipe with the hole is heated before application to speed cure, such as heating the pipe with an electric heat gun or other form of external heat. However, due to the time it takes to pre-heat the pipe and the time it takes for the epoxy to cure, the current repair process takes too long and the pipe cannot be rolled along the line as the partially cured epoxy will be damaged. The long length of time needed to repair the holes slows the pipecoating line, sometimes requiring the removal of the damaged pipe to the holding yard to be repaired later, leading to additional expense.

[0011] As such, it is desirable to provide a method of repairing a coating that overcomes the drawbacks with current methods, while also repairing the damaged areas of the coating as desired.

SUMMARY OF THE INVENTION

[0012] The present invention relates to a method of repairing a coating. In certain non-limiting embodiments, the coating includes: detecting at least one hole in a coating applied over a metal component; applying a liquid epoxy coating over the at least one hole; placing a peel ply heat resistant fabric over the liquid epoxy coating; curing the liquid epoxy coating including heating the peel ply heat resistant fabric positioned over the liquid epoxy coating; and removing the peel ply heat resistant fabric.

[0013] In certain non-limiting embodiments, the coating applied over a metal component comprising the at least one hole comprises a fusion bonded epoxy coating. The liquid epoxy coating can comprise a two part epoxy coating. The peel ply heat resistant fabric can comprise nylon, polyester, or a combination thereof.

[0014] In some non-limiting embodiments, the heating of the peel ply heat resistant fabric positioned over the liquid epoxy coating comprises placing a heated metal apparatus over the peel ply heat resistant fabric. The metal apparatus can be a metal pipe-iron, such as a metal pipe-iron shaped to conform to the metal component. The metal apparatus can also be held in place with magnets.

[0015] In certain non-limiting embodiments, the metal apparatus is removed after a time period selected within a range of from 30 seconds to 4 minutes. The metal component can be a metal pipe. The method can also include repairing multiple holes with any of the previously described method steps.

[0016] In some non-limiting embodiments, a kit for repairing a coating on a metal component includes: a liquid epoxy coating; a peel ply heat resistant fabric; and a metal apparatus that can be pre-heated to heat the peel ply heat resistant fabric when placed over the liquid epoxy coating [0017] The present disclosure also related to the following aspects.

[0018] Aspect 1: A method of repairing a coating comprising: detecting at least one hole in a coating applied over a metal component; applying a liquid epoxy coating over the at least one hole; placing a peel ply heat resistant fabric over the liquid epoxy coating; curing the liquid epoxy coating comprising heating the peel ply heat resistant fabric positioned over the liquid epoxy coating; and removing the peel ply heat resistant fabric.

[0019] Aspect 2: The method of aspect 1, wherein the coating applied over a metal component comprising the at least one hole comprises a fusion bonded epoxy coating.

[0020] Aspect 3: The method of aspect 1 or 2, wherein the liquid epoxy coating comprises a two part epoxy coating.

[0021] Aspect 4: The method of any one of the preceding aspects, wherein the peel ply heat resistant fabric comprises nylon, polyester, or a combination thereof.

[0022] Aspect 5: The method of any one of the preceding aspects, wherein the heating of the peel ply heat resistant fabric positioned over the liquid epoxy coating comprises placing a heated metal apparatus over the peel ply heat resistant fabric.

[0023] Aspect 6: The method of aspect 5, wherein the metal apparatus is a metal pipe-iron.

[0024] Aspect 7: The method of aspect 6, wherein the metal pipe-iron is shaped to conform to the metal component.

[0025] Aspect 8: The method of any one aspects 5-7, wherein the metal apparatus is held in place with magnets. [0026] Aspect 9: The method of any one aspects 5-8, wherein the metal apparatus is removed after a time period selected within a range of from 30 seconds to 4 minutes.

[0027] Aspect 10: The method of any one of the preceding aspects, wherein the metal component is a metal pipe.

[0028] Aspect 11: The method of any one aspects 5-9, wherein the metal apparatus is heated to a temperature within a range of from 150°F to 275°F. .

[0029] Aspect 12: The method of any one of the preceding aspects, wherein the metal component comprises multiple holes and the method comprises repairing the multiple holes according to any one of the preceding aspects.

[0030] Aspect 13: A kit for repairing a coating on a metal component comprising: a liquid epoxy coating; a peel ply heat resistant fabric; and a metal apparatus that can be pre-heated to heat the peel ply heat resistant fabric when placed over the liquid epoxy coating.

[0031] Aspect 14: The kit of aspect 13, wherein the liquid epoxy coating comprises a two part epoxy coating.

[0032] Aspect 15: The kit of aspect 13 or 14, wherein the peel ply heat resistant fabric comprises nylon, polyester, or a combination thereof.

[0033] Aspect 16: The kit of any one aspects 13-15, wherein the metal apparatus is a metal pipe-iron.

[0034] Aspect 17: The kit of aspect 16, wherein the metal pipe-iron is shaped to conform to a shape of a metal component where the liquid epoxy component is to be applied.

[0035] Aspect 18: The kit of aspect 16 or 17, wherein the metal component is a pipe and the metal pipe-iron is shaped to conform to a shape of the pipe.

BRIEF DESCRIPTION OF THE DRAWINGS

[0036] FIG. 1 is a schematic illustrating a stack of components applied during the method according to a non-limiting embodiment of the present disclosure.

DESCRIPTION OF THE INVENTION

[0037] For purposes of the following detailed description, it is understood that the invention may assume various alternative variations and step sequences, except where expressly specified to the contrary. Moreover, other than in any operating examples, or where otherwise indicated, all numbers expressing, for example, quantities of ingredients used in the specification and claims are to be understood as being modified in all instances by the term “about”. Accordingly, unless indicated to the contrary, the numerical parameters set forth in the following specification and attached claims are approximations that may vary depending upon the desired properties to be obtained by the present invention. At the very least, and not as an attempt to limit the application of the doctrine of equivalents to the scope of the claims, each numerical parameter should at least be construed in light of the number of reported significant digits and by applying ordinary rounding techniques.

[0038] Notwithstanding that the numerical ranges and parameters setting forth the broad scope of the invention are approximations, the numerical values set forth in the specific examples are reported as precisely as possible. Any numerical value, however, inherently contains certain errors necessarily resulting from the standard variation found in its respective testing measurement.

[0039] Also, it should be understood that any numerical range recited herein is intended to include all sub-ranges subsumed therein. For example, a range of “1 to 10” is intended to include all sub-ranges between (and including) the recited minimum value of 1 and the recited maximum value of 10, that is, having a minimum value equal to or greater than 1 and a maximum value of equal to or less than 10.

[0040] In this application, the use of the singular includes the plural and plural encompasses singular, unless specifically stated otherwise. In addition, in this application, the use of “or” means “and/or” unless specifically stated otherwise, even though “and/or” may be explicitly used in certain instances. Further, in this application, the use of “a” or “an” means “at least one” unless specifically stated otherwise.

[0041] As indicated, the present disclosure relates to a method of repairing a coating, such as a coating composed of a fusion bonded epoxy (FBE) on a metal component such as a metal pipe (e.g., a steel pipe). In certain non-limiting embodiments, a method of repairing a coating uses a formulated liquid epoxy coating (e.g. a two part liquid epoxy coating) and a peel ply heat resistant fabric composed of nylon and/or polyester that prevents damage to the liquid epoxy when the partially cured epoxy is rolled along the coating line. Additionally, the method can also use a pre-heated metal apparatus, such as a pipe-iron that can shaped to conform to the pipe. The pre-heated pipe-iron can be held in place with magnets when used. As the pipe- iron has been pre-heated away from the pipe, it can be immediately placed on top of the epoxy coating covered with the heat resistant fabric peel-ply and used to quickly cure the epoxy coating. As a result, no time is needed to pre-heat the pipe with a heat gun.

[0042] In certain non-limiting embodiments, once a hole in the FBE coating is detected on the steel pipe, the two-part liquid epoxy can be mixed together and applied onto the hole. The peel ply fabric can then be placed on top of the mixed epoxy and pipe. The pre-heated pipe-iron can then be placed on top of the epoxy and fabric. The pre-heated pipe-iron is sufficiently heated to expedite the curing of the epoxy. After a short period of time (for example selected within a range of from 30 seconds to 4 minutes), the iron is removed. The fabric can be left on the epoxy until it has been sufficiently cured or it can be left on the repair area as additional protection until it reaches the end of the coating line. The fabric prevents the partially cured epoxy from being damaged by sticking to parts of the coating line or to other coated portions of the pipe as it is rolled along. Once the two part epoxy is sufficiently cured, the peel ply fabric can be peeled off leaving an undamaged epoxy repaired area.

[0043] In certain non-limiting embodiments, the heat resistant fabric peel-ply can have a consistent texture of the cured surface without any trapped bubbles or pits. For instance, the tight weave of the heat resistant fabric can allow the release of the volatizing accelerators while keeping the liquid epoxy coating trapped next to the pipe. The liquid epoxy cannot penetrate through the tight fabric weave. In contrast, the use of a heat resistant sheet of plastic with a release agent coated onto it would trap the volatizing accelerators, resulting in pitting of the cured surface that would not pass quality inspection. The heat resistant fabric peel-ply can therefore both protect the coating repair and enhances its surface texture.

[0044] In some non-limiting embodiments, the pre-heated pipe-iron used to cure the liquid epoxy coating utilizes a peel ply to prevent pitting by allowing the release of the volatizing accelerator and also keeping the epoxy liquid in place. Most liquid epoxy coatings include an accelerator in the B side (curing agent side) of the two-part liquid epoxy coating. The accelerator does not crosslink into the resin, but instead volatizes off during cure as a gas or remains in the coating and reduces the properties of the coating.

[0045] Using a pre-heated pipe-iron to cure the liquid two-part epoxy coating with just a solid plastic release liner to protect the heated pipe-iron from the epoxy, the accelerator would be trapped in between the cured coating and the release liner, causing pitting and low spots in the coating. This would not be acceptable as it might allow corrosion to occur in the low spot. A peel ply, which is a tightly woven heat resistant fabric of either nylon or polyester placed on top of the liquid two-part epoxy, allows the accelerator to escape but does not let the epoxy coating to penetrate through the fabric. Once the coating is fully cured, the fabric can be peeled off of the surface. The finished coating has a uniform texture with no pitting or thin spots.

[0046] In certain non-limiting embodiments, the pipe-iron can be shaped to conform to the outside diameter of the pipe being repaired. A variety of diameters of steel pipe are used in the oil and gas industry, ranging from 4 inches to 42 inches. A different sized pipe-iron can be used for each different diameter of pipe, with the curve of its surface designed to conform to the outside diameter of the pipe. The flat edges at the top and bottom of pipe-iron can be approximately 4 inches wide while the curved section of the pipe-iron can be approximately 5- 6 inches long. The pipe-iron can be approximately * inch to 2 inches thick. The material can be composed of either steel, iron or some other metal, preferably steel for better durability. A handle can be attached on top of the pipe-iron. Magnets can be attached on both the flat edges of top and bottom of the pipe-iron that will hold it flush on the pipe. The pipe-iron can be preheated by electrical blankets or placed in pots heated by gas or electricity. Other methods of pre-heating are also possible. The pipe-irons can be pre-heated within in a temperature range of from 150°F to 275°F.

[0047] The metal of the pipe-iron can retain its heat sufficiently while it is used to cure a number of epoxy repairs, and then it can be placed back into its heating element to heat back up to a desired temperature. Multiple pipe-irons can also be available for the repair process to ensure continuous operation. If a pipe had multiple locations on it needing repair, a different pre-heated pipe-iron could be used on each repair area to speed-up the process.

[0048] In certain non-limiting embodiments, the heat of the pre-heated pipe-iron can be directly transferred to the epoxy coated repair area. With the current system of using a heat gun to pre-heat the pipe, the length of the pipe would draw some of the heat away, lengthening the time needed for the repair process. As the pipe-iron would be pre-heated in a heating blanket or pot, it could be directly placed on the epoxy repair area and the total of its heat would expedite the cure process, shortening the time needed for repair.

[0049] FIG. 1 is schematic illustrating a non-limiting embodiment of the stack of components applied during the method previously described. As shown in FIG. 1, holes 22 are present in a coating 20 (e.g., a FBE coating) applied over a metal component 10 (e.g., a metal pipe). As further shown in FIG. 1, a liquid epoxy coating 30 are placed over at least the holes 22, and a peel ply heat resistant fabric 40 is placed over the liquid epoxy coating 30. A heated metal apparatus 50 (e.g., a metal pipe-iron) is further applied over the peel ply heat resistant fabric 40 to heat and cure the liquid epoxy coating 30. It will appreciated that the metal apparatus 50 and peel ply heat resistant fabric 40 are removed as previously provided to undamaged final epoxy coating.

[0050] It is appreciated that the previously described method can be accomplished with a kit for repairing a coating applied over a metal pipe. The kit can include any one of the previously described liquid epoxy coatings, peel ply heat resistant fabrics, and optionally the metal apparatus for heating the peel ply heat resistant fabric s/curing the liquid epoxy coatings. [0051] It is appreciated that the previously described method can also provide a final product that includes an undamaged final epoxy coating over the metal component 10. In certain non-limiting embodiments the final coating includes the FBE 20 and cured epoxy coating formed from the liquid epoxy coating 30.

[0052] It will be readily appreciated by those skilled in the art that modifications may be made to the invention without departing from the concepts disclosed in the foregoing description. Accordingly, the particular embodiments described in detail herein are illustrative only and are not limiting to the scope of the invention, which is to be given the full breadth of the appended claims and any and all equivalents thereof.