Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05D—PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05D7/00—Processes, other than flocking, specially adapted for applying liquids or other fluent materials to particular surfaces or for applying particular liquids or other fluent materials
  • B05D7/50—Multilayers
  • B05D7/52—Two layers
  • B05D7/54—No clear coat specified
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B1/00—Layered products having a non-planar shape
  • B32B1/08—Tubular products
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B27/00—Layered products comprising a layer of synthetic resin
  • B32B27/06—Layered products comprising a layer of synthetic resin as the main or only constituent of a layer, which is next to another layer of the same or of a different material
  • B32B27/08—Layered products comprising a layer of synthetic resin as the main or only constituent of a layer, which is next to another layer of the same or of a different material of synthetic resin
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B27/00—Layered products comprising a layer of synthetic resin
  • B32B27/32—Layered products comprising a layer of synthetic resin comprising polyolefins
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B27/00—Layered products comprising a layer of synthetic resin
  • B32B27/38—Layered products comprising a layer of synthetic resin comprising epoxy resins
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B2307/00—Properties of the layers or laminate
  • B32B2307/50—Properties of the layers or laminate having particular mechanical properties
  • B32B2307/54—Yield strength; Tensile strength
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B2307/00—Properties of the layers or laminate
  • B32B2307/70—Other properties
  • B32B2307/732—Dimensional properties
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B2307/00—Properties of the layers or laminate
  • B32B2307/70—Other properties
  • B32B2307/732—Dimensional properties
  • B32B2307/737—Dimensions, e.g. volume or area
  • B32B2307/7375—Linear, e.g. length, distance or width
  • B32B2307/7376—Thickness
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B2597/00—Tubular articles, e.g. hoses, pipes
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
  • C09D163/00—Coating compositions based on epoxy resins; Coating compositions based on derivatives of epoxy resins

Definitions

• Crude oil contains corrosive ingredients such as carbon dioxide (CO2), hydrogen sulfide (H2S), organic acids, dissolved gases, and salt water.
• Oil sand comprises CO2 and corrosive ions such as chloride (Cl’), bicarbonate (HCO3 ), and sulfate (SO4 2 ’).
• CO2 carbon dioxide
• H2S hydrogen sulfide
• SO4 2 sulfate
• sand can be mixed with the flowing fluid to form multiphase solid-liquid mixtures. Flowing mixtures in piping and components, such as elbows, and pump impellers, may lead to solid particle erosion together with corrosion. Erosion and corrosion can reduce the equipment's lifetime due to a higher rate of material loss, resulting in replacement and downtime.
• Standard fusion-bonded epoxy (FBE) powder coatings are frequently used to coat and protect surfaces and components in the oil and gas industry and are known to provide effective corrosion resistances. These coatings are sometimes used as erosion-resistant coatings as well. However, these FBE coatings have been known to erode from pipe elbows within three months of exposure, followed by pipe failure within six months due to solids and corrosive material flowing through these components at high pressure and temperature. The combination of erosion and erosion/corrosion significantly reduces the lifetime of equipment used in the industry and leads to high rates of material loss and high costs associated with repair and shutdown of production.
• FBE Standard fusion-bonded epoxy
• the present invention provides an erosion-resistant coating system.
• the coating system includes a first coating applied to a substrate and a second coating applied over the first coating, the second coating comprising a thermoplastic component, wherein the coating system is erosion resistant.
• Fig. 4 is a graphical representation of the rate of erosion of a coating relative to bare steel.
• Fig. 7 is a graphical representation of the storage modulus (E’) as a function of temperature.
• Fig. 9 is a graphical representation of coating hardness of multiple coatings.
• component refers to any compound that includes a particular feature or structure. Examples of components include compounds, monomers, oligomers, polymers, and organic groups contained there.
• compositions described herein contain less than 5% by weight of the component, based on the total weight of the composition.
• essentially free of a particular compound or component means that the compositions described contain less than 2% by weight of the component, based on the total weight of the composition.
• completely free of a particular component means that the compositions described herein contain less than 1% by weight, based on the total weight of the composition.
• Particle size may be determined or analyzed by various methods known to those of skill in the art, including Laser Diffraction (LD), Dynamic Light Scattering (DLS), Dynamic Image Analysis (DIA) or Sieve Analysis. Unless otherwise indicated, particle size as described herein is determined by dynamic light scattering or otherwise provided by the manufacturer of a particular component.
• LD Laser Diffraction
• DLS Dynamic Light Scattering
• DIA Dynamic Image Analysis
• Sieve Analysis Unless otherwise indicated, particle size as described herein is determined by dynamic light scattering or otherwise provided by the manufacturer of a particular component.
• particle size as described herein is determined by dynamic light scattering or otherwise provided by the manufacturer of a particular component.
• particle size as described herein is determined by dynamic light scattering or otherwise provided by the manufacturer of a particular component.
• the term “erosion” refers to the damage to a material caused by mechanical movement or impact between particles and a surface. Specifically, as defined by NACE International, “erosion” means “ [t]he progressive loss of material from
• thermoplastic refers to a material that melts and changes shape when sufficiently heated and hardens when sufficiently cooled. Such materials are typically capable of undergoing repeated melting and hardening without exhibiting appreciable chemical change.
• thermoset refers to a material that is crosslinked and does not “melt.”
• the present description provides an erosion-resistant coating system.
• the coating system includes a first coating applied to a substrate and at least a second coating applied over the first coating, where the second coating is a thermoplastic component.
• Erosionresistant coating systems of the type described herein demonstrate erosion performance similar to steel when exposed to particular matter, including sand, for example. These coating systems also have excellent adhesion and appearance, and do not blister or swell when exposed to corrosive environments.
• the present description provides an erosion-resistant coating system that includes a first coating applied to a substrate.
• the first coating is applied to a substrate, optionally to a substrate with a primer coating applied thereon.
• the first coating is corrosion resistant.
• the first coating is thermoplastic.
• the first coating is a thermoset.
• the first coating may be a one-component coating.
• the first coating may be a two- component coating.
• the first coating may be a liquid coating and in even another aspect, the first coating may be a powder coating.
• the first coating is derived from a coating composition that includes at least one binder resin component.
• the binder resin component is selected from epoxy, polyester, polyurethane, polyamide, acrylic, polyvinylchloride, nylon, fluoropolymer, silicone, other resins, or combinations thereof.
• the binder resin component is an epoxy or polyepoxide binder resin component.
• Suitable epoxy resin components or polyepoxides preferably include at least two 1,2-epoxide groups per molecule.
• the epoxy equivalent weight is preferably from about 100 to about 4000, more preferably from about 500 to 1000, based on the total solids content of the polyepoxide.
• the polyepoxides may be aliphatic, alicyclic, aromatic, or heterocyclic.
• the polyepoxides may include substituents such as, for example, halogen, hydroxyl group, ether groups, and the like.
• Suitable epoxy resin compositions or polyepoxides used in the composition and method described herein include without limitation, epoxy ethers formed by reaction of an epihalohydrin, such as epichlorohydrin, for example, with a polyphenol, typically and preferably in the presence of an alkali.
• an epihalohydrin such as epichlorohydrin
• a polyphenol typically and preferably in the presence of an alkali.
• Suitable polyphenols include, for example, catechol, hydroquinone, resorcinol, bis(4-hydroxyphenyl)-2,2-propane (Bisphenol A), bis(4- hydroxyphenyl)- 1,1 -isobutane, bis (4-hydroxyphenyl)- 1,1 -ethane, bis (2-hydroxyphenyl)- methane, 4,4-dihydroxybenzophenone, 1, 5-hydroxynaphthalene, and the like.
• Bisphenol A and the diglycidyl ether of Bisphenol A are preferred.
• Suitable epoxy resin compositions or polyepoxides may also include polyglicydyl ethers of polyhydric alcohols. These compounds may be derived from polyhydric alcohols such as, for example, ethylene glycol, propylene glycol, butylene glycol, 1,6-hexylene glycol, neopentyl glycol, diethylene glycol, glycerol, trimethylol propane, pentaerythritol, and the like.
• epoxides or polyepoxides include polyglycidyl esters of polycarboxylic acids formed by reaction of epihalohydrin or other epoxy compositions with aliphatic or aromatic polycarboxylic acid such as, for example, succinic acid, adipic acid, azelaic acid, sebacic acid, maleic acid, fumaric acid, phthalic acid, tetrahydrophthalic acid, hexahydrophthalic acid, trimellitic acid, and the like.
• dimerized unsaturated fatty acids and polymeric polycarboxylic acids can also be reacted to produce polyglycidyl esters of polycarboxylic acids.
• the epoxy resin compositions or polyepoxides described herein are derived by oxidation of an ethylenically unsaturated alicyclic compound.
• Ethylenically unsaturated alicylic compounds may be epoxidized by reaction with oxygen, perbenzoic acid, acid-aldehyde monoperacetate, peracetic acid, and the like.
• Polyepoxides produced by such reaction are known to those of skill in the art and include, without limitation, epoxy alicylic ethers and esters.
• the epoxy resin compositions or polyepoxides described herein include epoxy novolac resins, obtained by reaction of epihalohydrin with the condensation product of aldehyde and monohydric or polyhydric phenols.
• examples include, without limitation, the reaction product of epichlorohydrin with condensation product of formaldehyde and various phenols, such as for example, phenol, cresol, xylenol, butylmethyl phenol, phenyl phenol, biphenol, naphthol, bisphenol A, bisphenol F, and the like.
• the first coating composition described herein is a powder coating composition.
• Thermoset materials are generally preferred for use as polymeric binders in powder coating applications.
• the powder composition described herein is a curable composition that includes at least one curing agent.
• the curing agent described herein helps achieve a solid, flexible, epoxy-functional powder composition.
• Suitable curing agents include, for example, epoxide-functional compounds (e.g., triglycidyl- isocyanurate), hydroxyalkyl amides (e.g., beta-hydroxyalkyl amide, commercially known as PRIMID), blocked isocyanates or uretdiones, amines (e.g., dicyandiamide), dihydrazides (e.g., adipic acid dihydrazide (ADH), isophthalic dihydrazide (IDH), sebacic dihydrazide (SDH), and the like), phenolic-functional resins, carboxyl-functional curatives, and the like.
• the curing reaction may be induced thermally, or by exposure to radiation (e.g., UV, UV-vis, visible light, IR, near-IR, and e-beam).
• the curing agent is selected to be compatible with the epoxy resin composition and operate to cure the powder composition at the temperature used to cure and apply the powder composition. Therefore, for the powder composition described herein, the curing agent is preferably selected to have a melting or softening point within the range of application temperature described herein, i.e., preferably about 150° C. to 300° C., more preferably about 220° C. to 260° C.
• the powder composition described herein is a fusion-bonded epoxy (FBE) composition.
• FBE fusion-bonded epoxy
• Preferred compositions include an epoxy resin prepared from a homogenous mixture of polyglycidyl ether of a polyhydric phenol, along with a dihydrazide or dicyandiamide curing agent.
• the fusion-bonded epoxy composition is present in an amount of about 20 to 90 wt %, preferably about 30 to 80 wt %, more preferably about 40 to 70 wt %, and most preferably about 50 to 60 wt %, based on the total weight of the powder composition.
• suitable commercially available FBE compositions include the PIPECLAD line of products (Sherwin-Williams), the CORVEL line of products (Akzo Nobel), and the like.
• Suitable FBE powder compositions as used herein include compositions with particle size of about 5 to 20 pm, preferably 10 to 15 pm (D10), about 40 to 70 pm, preferably 50 to 60 pm (D50), and about 100 to 140 pm, preferably 110 to 130 pm (D90), as measured by dynamic light scattering analysis.
• the first coating of the system as described herein is a cured film derived from an FBE powder composition.
• Suitable FBE powder compositions as used herein include compositions with high porosity resistance. Without limiting to theory, it is believed that higher porosity resistance provides better corrosion protection by minimizing the penetration of moisture into the substrate.
• a high porosity resistance coating or film is one that has minimal voids, or pores, on the film surface, i.e., the film has low porosity.
• the porosity of the film is determined and rated by methods known to those of skill in the art, including preferably by the method described in the standard CSA Z245.20 series (Plant-applied External Coatings for Steel Pipe).
• the first coating of the system described herein is a cured film with porosity rating of about 1 to 4, preferably 1 to 2, as determined by CSA Z245.20, wherein a rating of 1 indicates the lowest porosity and a rating of 5 the highest porosity.
• the first coating of the system described herein is a corrosion-resistant coating.
• the corrosion resistance of the coating described herein may be determined by standard methods known to those of skill in the art, including by measuring cathodic disbondment according to the methods described in CSA Z245.20 (Plant- Applied External Coatings for Steel Pipe).
• a coating is considered to have optimal corrosion resistance if it demonstrates a coating loss of less than 15 mm after 28-day exposure at 65°C.
• the corrosion resistance of the first coating is partially dependent on the application temperature.
• a spray applied FBE powder coating will melt and flow into the blast profile of the substrate and then cure to form a durable coating with minimal porosity and optimal corrosion resistance.
• pores, or voids where the film is not continuous are more likely to occur, which makes the substrate more permeable to water and could lead to corrosion of the substrate.
• the sprayed FBE powder may not melt sufficiently, which reduces its adhesion.
• the first coating of the erosion-resistant system described herein is applied to a substrate at a temperature of about 300F to 375F (approximately 149°C to 191°C), preferably 325F to 350F (approximately 163°C to 177°C).
• the substrate is heated to the desired temperature and the first coating is then applied to the heated substrate to allow the composition to melt, flow, and level out over the surface of the substrate.
• the first coating may be applied at a dry film thickness (DFT) appropriate for the anticipated end use of the substrate.
• DFT dry film thickness
• the first coating is applied at DFT of about 6 to 20 mil (approximately 152 pm to 508 pm), preferably about 8 to 16 mil (approximately 203 pm to 406 pm), more preferably about 10 to 14 mil (approximately 254 pm to 356 pm).
• the first coating of the erosion-resistant system described herein is applied over a primer that is in contact with and/or directly bonded to the unprimed, pretreated, or clean-blasted substrate surface.
• the primer is intended to be a corrosionresistant coating applied to the metal, and the first coating of the erosion-resistant system described herein is then a basecoat applied over the primer layer.
• the primer may be a powder coating or a liquid coating.
• the primer coating or layer is optional, however, and the first coating or basecoat may be applied directly to the unprimed, pretreated, or clean-blasted substrate surface even without a primer coating.
• the primer layer may comprise a phenolic primer such as a phenol-formaldehyde resin or an epoxy-phenolic resin, for example.
• the present description provides an erosion-resistant coating system that includes a second coating applied to a substrate.
• the second coating is applied to a substrate with a first coating applied thereon.
• the second is applied directly to the substrate without a first coating applied thereon.
• the second coating is an erosion-resistant coating.
• the second coating is thermoplastic.
• the second coating is a thermoset.
• the second coating may be a one-component coating.
• the second coating may be a two-component coating.
• the second coating may be a liquid coating and in even another aspect, the second coating may be a powder coating.
• the erosion-resistant second coating is a thermoplastic coating, preferably a powder coating composition that includes at least one binder resin component.
• the binder resin component is a polyolefin selected from polyethylene, polypropylene, and the like, and mixtures or combinations thereof.
• the polyolefin is a modified component, preferably an acid- modified component, obtained by combining a polyolefin with at least one a,P-unsaturated carboxylic acid or acid anhydride thereof, such as, for example, maleic acid, itaconic acid, citraconic acid, acid anhydride thereof, or mixtures or combinations thereof.
• acid anhydride forms are generally preferred, and maleic acid anhydride is more preferred.
• modified polyolefins as described herein include, without limitation, maleic acid anhydride-modified polypropylene, maleic acid anhydride-modified propyleneethylene copolymers, maleic acid anhydride-modified propylene-butene copolymers, maleic acid anhydride-modified propylene-ethylene-butene copolymers, and the like. These acid- modified polyolefins can be used singly or as mixtures or combinations of two or more modified polyolefins.
• the second coating is derived from maleic anhydride- modified polypropylene (PP-MA).
• PP-MA maleic anhydride- modified polypropylene
• Crystalline or semi-crystalline forms of PP-MA are particularly preferred, as they demonstrate better adhesion to a substrate surface, and accordingly form a more effective erosion-resistant coating, as well as providing effective corrosion resistance and barrier properties.
• the crystalline PP-MA described herein has molecular weight (Mw, weight average molecular weight) of 40,000 to 180,000, more preferably 50,000 to 160,000, even more preferably 60,000 to 150,000, particularly preferably 70,000 to 140,000, and most preferably 80,000 to 130,000.
• the second coating is an erosion-resistant powder coating derived from a binder resin component comprising a modified polyolefin, preferably maleic anhydride-modified polypropylene (PP-MA).
• PP-MA maleic anhydride-modified polypropylene
• the second coating as described herein may be a single layer or multi-layer extruded thermoplastic film.
• the second coating as described herein is an erosion-resistant powder coating. Without limiting to theory, it is believed that the particle size (D90) of the second coating is critical to effective erosion resistant performance. By maintaining the D90 particle size below about 300 pm, it is possible to limit or reduce the porosity of the erosion-resistant coating.
• a porous coating is one that has significant voids or gaps in the coating, and such coatings are more susceptible to erosion and failure when in contact with large particulate matter such as the sand or grit encountered during oil and gas drilling operations, for example.
• the extruded films for the second coating described herein are derived from maleic anhydride-modified polypropylene sieved through an 84T mesh and having particle size of about 40 to 90 pm, preferably 50 to 70 pm (D10), about 120 to 160 pm, preferably 130 to 150 pm (D50), and about 220 to 260 pm, preferably 230 to 250 pm (D90), as measured by as determined by sieve analysis according to ASTM D1921-18.
• higher porosity resistance provides better erosion resistance by minimizing areas where contact with large particulate matter could cause erosion or coating loss.
• the second coating may be applied at a dry film thickness (DFT) appropriate for the anticipated end use of the substrate, i.e., specifically as an erosionresistant coating. Accordingly, in an embodiment, the second coating is applied at DFT of about 20 to 100 mil (approximately 508 pm to 2540 pm), preferably about 30 to 85 mil (approximately 762 pm to 1651 pm), and more preferably about 40 to 60 mil (approximately 1016 pm to 1524 pm).
• DFT dry film thickness
• the coating system described herein is an erosion-resistant thermoset-thermoplastic composite having low storage modulus (E’).
• the storage modulus is less than about 4000 MPa, preferably 1000 to 3000 MPa at 25°C.
• the erosion-resistant coating system as described herein may also be characterized in terms of the ratio of the loss modulus (E”) and the storage modulus (E’) of the coating. This is also expressed as tan 5, and for the system described herein, optimal tan 5 are about 0.01 to 0.3, preferably below 0.1 at 25°C.
• the erosion-resistant coating system is a thermoplastic composite with low storage modulus (E’) that remains stable over time on exposure to produced water.
• the term “produced water” is a term used in the oil, gas, and geothermal industry to describe water that is produced as a byproduct during the extraction of oil and natural gas or used as a medium for heat extraction.
• Water that is produced along with the hydrocarbons is generally brackish and saline water in nature and tends to cause more corrosion and/or erosion of the substrate material. Therefore, an effective erosion-resistant system must be impermeable or resistant to the effects of produced water and show little to no change to the storage modulus over time when exposed to erosive conditions.
• the erosion-resistant coating described herein shows almost no change in storage modulus (E’) after prolonged exposure of more than 30 minutes to produced water, in contrast to a commercially available thermoplastic coating system (nylon) shown for comparison.
• the erosion-resistant coating system described herein demonstrates erosion performance comparable to an uncoated steel substrate on exposure to produced water. Erosion performance is determined according to the methods described in ASTM G76-18 (Standard Test Method for Conducting Erosion Tests by Solid Particle Impingement Using Gas Jets). Sample or test substrates coated with the erosion-resistant coating system described herein show the same rate of erosion as a blank steel sample used as a control (see Figure 4). [0065] The erosion performance of the coating system described herein may also be determined by immersion testing. In an aspect, the erosion-resistant coating system described herein demonstrates optimal immersion resistance at 140F (60°C) following at least 28 days of exposure to produced water, both in unstirred and stirred conditions.
• the stirred conditions are meant to simulate the flow or movement of liquid and gas in a pipeline and provide a more effective measure of the erosion resistance of the coating system.
• the erosion-resistant coating system as described herein (Coating #5) has a much lower rate of erosion following immersion testing than a commercially available coating system (Coating #3, nylon) shown for comparison.
• the second coating is applied over the first coating immediately, i.e., when the first coating is substantially uncured.
• the first and second coating compositions are then cured together under conditions effective to form a cured coating (thermoset-thermoplastic composite coating), i.e., by heating the coated substrate to a temperature of about 220°C to 240°C, preferably 232°C for 30 to 60 minutes, and then allowing the coated substrate to cool.
• the second coating is applied over the first coating after the first coating is substantially cured.
• the substrate may first be cleaned or treated to remove surface impurities, by sandblasting, for example prior to heating and applying the first coating composition.
• the substrate may have a primer applied thereon, preferably a liquid phenolic primer, before the first coating composition is applied.
• the second coating composition is applied over the first composition in a single pass, i.e., only one layer of the second coating composition is applied.
• the second coating composition is applied over the first composition in multiple passes, preferably 2 to 6 passes, or the number of passes required to reach optimal dry film thickness (DFT) of 20 to 100 mil (approximately 500 pm to 2540 pm) for the entire erosion-resistant composite system.
• DFT dry film thickness
• the second coating has a DFT of 20 to 80 mils, 35 to 80 mils, and 35 to 60 mils.
• the first coating composition described herein may be applied to a substrate, such as the inner surface of a steel pipe, for example, by various means known to those of skill in the art, including the use of fluid beds and spray applicators. Most commonly, an electrostatic spraying process is used, wherein the particles are electrostatically charged and sprayed onto a substrate that has been grounded so that the powder particles are attracted to and cling to the article. The coating is then cured, either before or after application of a second coating composition, and such curing may occur via continued heating, subsequent heating, or residual heat in the substrate. For example, the coating may be applied to a heated substrate such that curing occurs in a continuous manner.
• the second coating preferably a powder coating
• the second coating is applied over the first coating by various means known to those of skill in the art, including electrostatic spray application, or fluidized bed coating application.
• electrostatic spray application or fluidized bed coating application.
• a spray application process is used, where the second coating is electrostatically applied over the first coating before the first coating is gelled or cured.
• the coated substrate is then heated after the second coating is applied to allow both the first and second coating compositions to be in a molten or flowing state at the same time, thereby increasing crosslinking and interlayer adhesion and producing a molecular composite that is effective as an erosion-resistant coating system.
• the erosion-resistant coating system described herein may be applied over a wide variety of substrates, including steel substrates used in the transport of oil, gas, and other substances.
• the erosion-resistant coating system described herein is applied over a tubular good.
• tubular good may refer, without limitation, to rolled metal products used in the production of oil and gas. Examples include, without limitation, drill pipe, line pipe, casing, lining, coupling, connectors, production tubing, delivery tubing, elbows, straight pipe sections, spools, and other accessories or combinations thereof used in the production of oil and gas. These products are manufactured in different grades and in different sizes and lengths according to specifications provided by the American Petroleum Institute (API).
• API American Petroleum Institute
• a profilometry technique using the Keyence VHK-7000 series microscope is used.
• the microscope begins by focusing on one end of the test sample, collecting an image, and then moving to successive locations on the test sample to take more images. These images are then collated into a composite in-focus image of the sample that can be used to measure the depth of erosion craters (Zc) on the test sample relative to a steel control or blank (Zs).
• the erosion rates of the steel control (Es) and of the test samples (Ec) are calculated by dividing the depth of the crater by the weight of the silica sand that created the crater, as demonstrated by the equations below. Erosion measurements are taken on coated panels in a cured (dry) state and post-exposure (wet) state. Use of this method is illustrated in Figures 1-3.
• DMA Dynamic Mechanical Analysis
• DMA curves are used to compare the structure of multiple coatings.
• the glass transition temperature (Tg) where the coating changes from a glassy to a rubbery material with a significant increase in free volume, is noted first by a decrease in E,’ at the middle by a peak in E,” and by a peak in the tan 5 curve near the end. Above the Tg, there may be a flat region in the E’ curve often called the plateau modulus. This modulus value is often indicative of the crosslink density of a material. Equivalent systems with a higher E’ plateau will usually provide better barrier performance provided they also have good adhesion and flexibility. Results of DMA testing for erosion-resistant coatings is illustrated in Figures 7 and 8.
• specimens from the coating free films are assessed for wet erosion performance by DMA using standard commercially available solids analyzers, such as the TA Instruments RSA-G2, for example.
• Film tension fixtures and a submersion apparatus are used to assess samples immersed in either deionized water or produced water, and testing is conducted isothermally at 60°C (140°F) at 1 Hz frequency, 0.1% strain and 0.1 N pretension. After a 2-minute preconditioning in air, the test fluid, (preheated to 60°C (140°F)) is added so the film plasticization can be observed through the modulus drop over a 30-minute test duration. Immersion testing can be used to compare the effects of plasticization on mechanical properties. Significant changes seen could portend even larger changes in the field where the exposure is over longer times and at greater pressures. Results for DMA testing of immersed erosion-resistant coatings is illustrated in Figure 6.
• a micro-indenter such as Fischerscope HM2000, for example
• Fischerscope HM2000 Metallic Materials - Instrumented indentation test for hardness and materials parameters
• coated test panels are used in dry, ambient conditions of 23°C temperature and relative humidity of 25%.
• a Vickers indenter is lowered into the coating applied to a test panel to a force of 20 mN, held for 5 seconds and then removed.
• the contact area for indentation is from 1 to 4 p 2 and to a depth of up to about 3 pm. Results for micro-indenter testing of erosion resistant coatings is illustrated in Figure 9.
• coated test panels are subjected to immersion testing in produce water under continuous agitation at temperatures of about 60°C.
• the test panels are placed in a panel holder immersed in a mixing vessel containing an 80/20 by volume mixture of production water and kerosene (i.e., “produced water”), using separate samples for each time interval. After a given period of time (14, 21, or 28 days), the samples are removed from the water, wiped dry, and then subjected to erosion testing.
• metal test panels are coated with a one- component (IK) primer at a dry film thickness of 0.12 to 18 pm and then further coated with the coatings described herein.
• the coatings are allowed to cure, and coated panels are assessed for cure using differential scanning calorimetry (DSC).
• DSC differential scanning calorimetry
• the coated panels are then placed in autoclave conditions for 28 days at 60°C at varying pressures of 100 psi (7 day), 200 psi (14 day), 400 psi (21 day) and 800 psi (28 day). At seven-day intervals, the coated panels are reviewed for appearance, adhesion, swelling, and blistering.
• ASTM D6677-18 Standard Test Method for Evaluating Adhesion by Knife is used to assess adhesion between the first coating and the second coating. A rating of 6-10 is considered acceptable for the erosion-resistant coating. If no appreciable changes are seen, the test panels are returned to the autoclave for an additional seven days at a higher pressure.
• Example 1 The test formulations of Example 1 were evaluated for erosion resistance as described in the test methods above. In order to be an effective erosion coating, each formulation must adhere to the substrate while not swelling or blistering on exposure to produced water or other simulated field situations. In addition, an effective coating is one that passes the autoclave test as described above.
• Results of various performance evaluations are as depicted in Figure 4 (rate of erosion relative to bare steel), Figure 5 (DMA comparison of immersion testing for coatings #3 and #5), Figure 6 (storage modulus following immersion testing), Figure 7 (storage modulus as a function of temperature), Figure 8 (tan 5), and Figure 9 (hardness following autoclave testing).
• a metal test substrate was heated to 350F (177°C) for 60 minutes, and a FBE coating was then electrostatically applied to the substrate, immediately followed by application of a thermoplastic powder topcoat.
• the multi-layer coated substrate was cured in an oven at 450F (232°C) for 30 to 75 minutes and then allowed to cool to room temperature (23°C).

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