Corrosion resistant metal tube and process for making the same

Abstract

A corrosion resistant multi-layer tube comprises a metal tube; a zinc layer bonded to the metal tube outer surface; a surface treatment layer bonded to the zinc layer; a priming layer; a first polymeric layer bonded to the priming layer; a second polymeric layer bonded to the first polymeric layer. A process for manufacturing the tube comprises the step of extruding multiple layers of a melt-processible thermoplastic to a pretreated metal tube having an external surface with at least a zinc based coating, a sealant coating on top of the zinc based coating, and a primer coating on top of the sealant coating. The primer coating is preferably applied by an airless spray system in a closed atmosphere, wherein substantially no volatile organic compounds escape into the atmosphere. The polymeric layer(s) remain adhered to the metal tube, even when exposed for prolonged periods to aggressively corrosive environments.

Description

BACKGROUND OF THE INVENTION

[0002] This invention relates to a multi-layer coated metal tube, and more particularly to a metal tube having a primed outer surface coated with a plurality of layers of plastic material securely bonded thereto.

[0003] Metal pipes often have their outer surfaces covered with a protective coating. These pipes are used for conveying hydraulic fluids (such as for brakes, transmissions, power steering, fans, and the like), fuels (such as methanol, ethanol, gasoline, additives, diesel, kerosene, jet fuel, and mixtures thereof), vapor, and the like in a motor vehicle. As such, these pipe lines are located under the body of the vehicle. Since they are used in such a harsh environment, the pipes are required to have a high degree of corrosion resistance, scratch resistance, impact strength and mechanical wear resistance. In cold climates, it is not unusual to encounter road salt sprinkled onto road surfaces in order to prevent freezing of water on the road surfaces and the inherent dangers caused thereby. The popularity of spreading road salt has created a serious problem of pipe corrosion. The pipes are also vulnerable to damage or wear from stones or mud spattered by rotating wheels of the vehicle. It is, therefore, necessary that the pipes attached to the underbody of the vehicle be coated so as to resist both chemical corrosion and mechanical damage or wear.

[0004] Flexible fuel vehicles (FFVs) often are designed to be fueled by methanol, ethanol, gasoline, and/or any combination of these fuels. Certain fuel blends may corrosively attack metals, even some types of stainless steel. If corrosion is prolonged, fuel and/or hazardous fluids may leak from the tubing. However, emissions standards, for example those issued by the California Air Resources Board (CARB) and the U.S. EPA, mandate no leakage or permeation for as high as 150,000 miles or 15 years.

[0005] A double-rolled steel pipe has been proposed that is made by rolling a steel strip or hoop twice and brazing its longitudinal edges by means of a copper plating layer, or a seam welded steel pipe, where the pipe has an outer surface coated with an electroplated zinc film. The zinc film has an outer surface coated with a relatively thin special chromate film having, for example, an olive color. Chromate is typically used to enhance the adhesion of the subsequent layer by making the surface rougher. The chromate film has an outer surface coated with a fluorinated resin film. The fluorinated resin film is formed by impregnating the chromate film with a dispersion of polyvinyl fluoride immediately after the formation of the chromate film when it is still in the state of a gel, and drying them under heat, so that the fluorinated resin film may form an intimate bond with the chromate film. When the chromate film is formed by treating the pipe with a solution, it requires large amounts of a chromium compound and an organic acid, such as formic acid, used as a reducing agent. It is necessary to supply the treating solution with the chromium compound frequently, and to renew it at regular intervals of time in order to maintain a constant film forming capacity. The waste solution, however, contains a large amount of chromium having a valence of 6, which is a toxic substance. As such, the disposal of this toxic waste solution is very costly. Although the chromate film as formed is highly resistant to corrosion, the heat to which it is exposed during the formation of the resin film deprives it of water and thereby makes it brittle. Any plastic deformation of the pipe, such as may result from bending or double flaring, and/or any elastic deformation, such as may result from pipe handling prior to or during assembly, may form fine cracks in the chromate film which lowers its rustproofing properties.

[0006] It has also been proposed to provide a corrosion resistant pipe where a metal pipe is provided with an outer surface coated with a zinc film, a chromate film, an intermediate layer consisting sequentially of an epoxy resin, and a polyvinyl fluoride film formed one on top of another in the order listed.

[0007] A plastic-coated steel tube has also been proposed where a steel tube has an inner layer of at least one cross-linked polyolefin modified with a hydrolyzable silane and an outer unmodified or soot-blended polyolefin layer on the exposed surface of the inner layer.

[0008] A process for coating metal tubes with plastic material has also been disclosed where a fixed metal tube is heated to a temperature above the melting point of the plastic material to be employed, thereafter causing a mixture of plastic powder and air to pass through the metal tube whereby the plastic material is fritted onto the inside surface of the tube, thereafter rotating the metal tube and applying to the exterior surface thereof in a plurality of stages a plastic material, the plastic material being electrostatically sprayed onto the rotating metal tube. After each stage of electrostatically applying plastic to the outside surface of the metal tube and applying plastic material to the inside surface thereof, the plastic material is completely melted and smoothed. However, this process has several drawbacks, including that it is a batch process (as opposed to a continuous process); it requires rotation of the tube; and the cure time of the plastic material is quite slow, eg. several minutes. Thus, this process is rather inefficient, both from a cost and time standpoint.

[0009] An automobile tube line for a brake, fuel or hydraulic system has also been disclosed with an interior steel tube having a galvanized exterior layer with an additional exterior olive chromated layer which is wrapped in an additional Nylon 12 layer casing where the plastic casing is a polyamide layer applied by extrusion on top of the olive chromated layer.

[0010] In U.S. Pat. No. 5,590,691, which is incorporated herein by reference, there is disclosed a metal tube having an extruded multiple plastic layer coating bonded thereto. This tube is very corrosion resistant, yet may not be suitable in aggressively corrosive environments such as for example upon exposure to fluid soaking in 85% ethanol.

[0011] Thus, it is an object of the present invention to provide a corrosion resistant metal tube which withstands prolonged exposure to corrosive environments, including aggressively corrosive environments. It is another object of the present invention to provide such a tube and process for making the same which advantageously substantially contains any volatile organic compounds, thereby substantially preventing any undesirous venting of VOCs to the atmosphere. It is a further object of the present invention to provide a process which captures and re-uses any primer material applied to the tube, thereby advantageously substantially eliminating waste of raw material(s) and substantially preventing undesirous venting/overspray of primer to the surrounding environment. Still further, it is an object of the present invention to provide such a tube and process for making the same which exhibits good adherence between the tube and a subsequent corrosion resistant layer(s) for prolonged periods of time. Further, it is an object of the present invention to provide a process for making such a tube which-is high speed thereby being advantageously cost effective.

SUMMARY OF THE INVENTION

[0012] It is desirable in the present invention to provide brake lines and fuel lines, and other lines which could be damaged by the regular use of an automobile, which can meet the continuous demand of traffic conditions and possible exposure to corrosive fluids, and therefore must have a long lasting durability of ten years or more. In such application areas, resistance to corrosion, resistance against breaking, cracking or bursting due to internal pressure, resistance to stone impact, and a high corrosion resistance against winter salt are all desirable characteristics. At this time, tube lines made of steel are currently being used in a large capacity. For brake lines, double-wrap steel tubes are suitable, whereas single wall straight bead welded steel pipes are more appropriate for fuel lines.

[0013] The corrosion resistant metal tube and process for making according to the present invention provides numerous advantages over the prior known tubing configurations. In particular, tube having a priming layer between the polymeric layer(s) and the pretreated tube promotes adherence of the polymeric layer(s), even when exposed for prolonged periods of time to aggressively corrosive environments, such as for example to 85% ethanol fluid soaks. Further, the process for applying the primer coating according to the present invention is environmentally friendly. Still further, the polyamide 12 material of choice, having a lower viscosity and lower molecular weight, allows for higher line speeds for more efficient and cost effective production.

[0014] The multi-layer tube according to the present invention comprises a metal tube having an outer surface; a zinc layer bonded to the metal tube outer surface, wherein the zinc layer is selected from the group consisting of zinc plating, zinc nickel alloys, zinc cobalt alloys, zinc aluminum alloys, and mixtures thereof; a surface treatment layer bonded to the zinc layer, wherein the surface treatment layer is selected from the group consisting of a zinc/aluminum/rare earth alloy, phosphate, chromate, and mixtures thereof; a priming layer; a first polymeric layer bonded to the priming layer, wherein the first polymeric layer is selected from the group consisting of thermoplastic elastomers, ionomers, nylons, fluoropolymers, and mixtures thereof; and a second polymeric layer bonded to the first polymeric layer, wherein the second polymeric layer is selected from the group consisting of nylons, thermoplastic elastomers, fluoropolymers, and mixtures thereof.

[0015] A process according to the present invention for manufacturing a multi-layer tubing for conveying fluids comprising the step of extruding multiple layers of a melt-processible thermoplastic to a pretreated metal tube having an external surface with at least a zinc based coating, a sealant coating on top of the zinc based coating, and a primer coating on top of the sealant coating. The primer coating is preferably applied by an airless spray system in a closed atmosphere, wherein substantially no volatile organic compounds escape into the atmosphere.

[0016] Other objects, advantages and applications of the present invention will become apparent to those skilled in the art when the following description of the best mode contemplated for practicing the invention is read in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The description herein makes reference to the accompanying drawings wherein like reference numerals refer to like parts throughout the several views, and wherein:

[0018] FIG. 1 is a view of the paint booth used in conjunction with the closed atmosphere, airless spray system according to the present invention for applying the primer;

[0019] FIG. 2 is a further view of the paint booth used in conjunction with the closed atmosphere, airless spray system according to the present invention for applying the primer;

[0020] FIG. 3 is a further view of the paint booth used in conjunction with the closed atmosphere,-airless spray system according to the present invention for applying the primer;

[0021] FIG. 4 is a cross-sectional view of a tubing according to the present invention with the layer thicknesses exaggerated for purposes of illustration;

[0022] FIG. 5 is a further view of the paint booth used in conjunction with the closed atmosphere, airless spray system according to the present invention for applying the primer; and

[0023] FIG. 6 is a schematic view of the closed atmosphere, airless spray system according to the present invention for applying the primer.

DESCRIPTION OF THE PREFERRED AND ALTERNATIVE EMBODIMENTS

[0024] The multi-layer tubing 10 according to the present invention includes a metal tube or pipe 12. The metal tube 12 may be welded steel tube, brazed steel tube, aluminum, copper or stainless steel. The process of the present invention is capable of applying a multi-layer coating over any rigid or semi-rigid tubular material. Of particular interest in the present invention, is the mechanical durability and corrosion resistance advantage obtained with carbon steel in either a welded single wall or brazed double wall form of tube or piping. Application of multi-layer coatings on other materials may be of a decorative nature with some protection also being obtained, for example improved chemical resistance of the outer shell of the multi-layer coating over the underlying rigid or semi-rigid tubular material.

[0025] The metal tubing 12 is pretreated as required through various clean and rinse stages. In addition, the pretreating of the metal surface may also include pickling to remove oxides and to improve the metal surface for deposition of a metal based coating, such as a zinc based coating that is applied by hot dip galvanization, sometimes referred to as the “hot process” as previously described, or the preferred method of electrolytic bath coating or plating sometimes referred to as the “electrolytic or cold process” as previously described. In the alternative, previously pretreated metal tubing 12 may be supplied to the zinc based coating process step according to the present invention, or a previously zinc base coated metal tubing 12 may be supplied to the surface treating step of the process according to the present invention. In either case, metal tubing 12 with a zinc based coating applied thereon in a range of 0.4 to 1.0 mil is either produced or supplied for subsequent treating as will be disclosed hereinafter according to the present invention.

[0026] The external surface of the zinc based coating is treated to seal the zinc based coating to prolong its corrosion resistance and to provide a suitable surface for application of and bonding to extruded multiple layers of plastic to be subsequently supplied. The surface treatment of the zinc based coating is at least one of the surface sealing treatments selected from the group of a phosphate coating, a chromate coating including the clear, yellow and green versions, a zinc-aluminum alloy coating, and combinations thereof. A suitable zinc-aluminum alloy and coating is described in U.S. Pat. No. 4,448,748 which is incorporated herein by reference, and-ASTM Designation: B750-88 provides a standard specification for zinc-5% aluminum-mischmetal alloy in ingot form hot-dip coatings, which is also incorporated herein by reference. Metal tubing pretreatment prior to plastic application can include combinations such as zinc-aluminum alloy with a phosphate coating and a chromate coating, zinc plate with a chromate coating, zinc plate with a phosphate coating and a chromate coating, galvanized zinc with a phosphate coating and/or a chromate coating, zinc-nickel alloy plate with a phosphate coating and/or a chromate coating, zinc-cobalt alloy with a phosphate coating and/or a chromate coating, a chromate coating of the clear, yellow and green versions, and combinations thereof. The pretreatment of the metal surface prior to the zinc base coating can include sand, shot or bead blasting, or other means of abrading the surface to roughen it, or detergent cleaning with rinse and acid pickling followed by a rinse. Any suitable surface abrading or etching process, either chemical or mechanical, may be used as a pretreatment prior to any other surface treatment and/or prior to extruding plastic onto the metal surface. The chromate coating can be applied as a wash having essentially no remaining weight. The zinc-aluminum alloy coating can be applied with a weight selected in a range of between 36 to 95 g/m2 inclusive, and with a preferred weight range of between 75 to 80 g/m2 inclusive and a most preferred weight of 78 g/m2. The phosphate coating can be applied with a weight in the range of between 120 to 250 mg/ft2 (1.292 to 2.691 g/m2) inclusive. The zinc based coating on the metal surface is preferably a weight in the range of between 13 to 35 microns inclusive.

[0027] Various combinations of multi-layer tubing 10 according to the present invention have been prepared with metal tube 12 having a {fraction (3/16)} inch diameter brazed tube, or {fraction (5/16)} inch and ⅜ inch diameter welded steel tube. The process according to the present invention is not size dependent, and therefore it is anticipated that other sizes, including smaller sizes and larger sizes, of metal tube 10 can be processed according to the present invention.

[0028] The zinc-aluminum galvanizing alloy or coating preferably contains from about 85% to 97% zinc, from about 4% to 15% aluminum and at least about 5 ppm mischmetal (a variety of known rare earth containing alloys).

[0029] After treating the surface of the zinc based coating or layer 14 with the surface treatment layer 16, a primer 17 is applied. The primer 17, which promotes adherence of the polymeric layer(s) to the metal substrate, even when exposed for prolonged periods of time to aggressively corrosive environments (such as for example to 85% ethanol fluid soaks) will be discussed further below. Multiple plastic layers are extruded on the treated surface 16 of the zinc based layer 14. In the alternative, multiple plastic layers can be extruded on to the external surface of the metal tube 12 without pretreatment. In either case, the multiple plastic layers preferably include at least an alloy or bonding layer, referred to herein as a first layer 18 formed on top of the treated surface layer 16 and an external shell or second layer 22 exposed to the outside environment. An optional intermediate or third layer 20 may be provided between the first layer 18 and the second layer 22 and may include one or more sublayers of plastic materials.

[0030] Prior to extruding the multiple plastic layers onto the treated surface 16, the metal tube 12 is preheated to temperatures in the range of between 177° C. to 232° C. (350° F. to 450° F.) inclusive, with a preferred range of between 204° C. to 232° C. (400° F. to 450° F.) inclusive. The multiple layers of extruded plastic form a coating over the treated surface 16 with an overall thickness in a range of between 75 to 300 microns (3 to 12 mils), with a preferred range of between 125 to 250 microns (5 to 10 mils). Individual plastic layers can be applied with a thickness in a range of between 10 to 250 microns (0.3 to 10 mils) inclusive, with a preferred range of between 125 to 250 microns (5 to 10 mils) inclusive.

[0031] A more detailed description of the process according to the present invention follows. The tubing 12 as previously described is subjected to a clean and rinse step followed by a pickling process step to remove oxides and to improve the external metal surface for subsequent flash plating. After the pickling step, the metal tubing 12 is subjected to a rinse step. The electroflux and flash plate with zinc step then applies the zinc based layer of a thickness in the range of 0.4 to 1.0 mil inclusive. A zinc-aluminum alloy coating is then applied to the external surface of the zinc based layer. A suitable zinc-alloy coating is commercially available under the tradename GALFAN from Eastern Alloys, Inc. of Maybrook, N.Y. The sealing step of applying GALFAN while controlling the thickness in a range of 36 to 95 g/m2 with a most preferred thickness of 78 g/m2, is followed by a water quench step to bring the tubing 12 back to ambient temperature, followed by a rinse step. It is to be understood that any of the quenching steps as discussed herein may be performed using any suitable material or process. A phosphate surface may be applied to the external surface of the GALFAN coating for improved adhesion of subsequent layers. A rinse step follows the phosphating step. The application of a chromate coating occurs to seal the phosphate surface applied. The phosphate surface is preferably applied with a thickness in the range of 120 to 250 mg/ft2 (1.292 to 2.691 g/m2), while the chromate coating may be applied as a wash having essentially no remaining weight on the tubing upon completion. After the chromate wash step, the multiple layers of plastic are extruded onto the metal tubing 12. Preferably, the tubing has been heated in a range of between 375 to 450° F. inclusive with a preferred temperature of 425° F. prior to the application of the multiple layers of plastic. A conventional mechanical applicator or extrusion head is used for coextruding the multiple layers of plastic simultaneously onto the surface of the preheated metal tube 12. In the preferred configuration, vacuum is applied to the head of the applicator to pull the plastic material down onto the surface of the preheated tube 12. The vacuum applied is preferably in the range of 1 inch to 22 inches of water (where 28 inches of water is equal to atmospheric pressure), with a preferred vacuum pressure of 10 inches of water. After extrusion of the multiple layers of plastic, the tubing 12 is subjected to a quench, which can be a water quench, oil quench or other material quench as required, and is thereafter coiled or cut to finished length.

[0032] In lieu of coextrusion, the process could also be carried out as a cross-head application wherein the layers are applied synchronously instead of simultaneously. However, this process is not as preferred as the coextrusion, in that there is a greater likelihood of loss of bonding efficiency and bonding properties, and there tends to be less control over layer thicknesses.

[0033] Referring now to FIG. 4, the multi-layer tube of the present invention is designated generally as 10. Multi-layer tube 10 comprises a tube or pipe 12 having an outer surface 13. Tube 12 may be formed in any conventional manner and of any suitable material. For example, tube 12 may be a welded single wall steel tube, a brazed double wall steel tube, etc. Further, aluminum, stainless steel and the like also may be used. Yet still further, tube 12 may be formed from any rigid or semi-rigid tubular material. Tube 12 may be of circular cross section as shown, however, it is to be understood that tube 12 may be formed of any suitable size and/or shape, including square, rectangular and other geometric configurations.

[0034] A zinc layer 14 is bonded to the metal tube outer surface 13. It is to be understood that any suitable zinc layer 14 may be used in accord with the present invention. However, in the preferred embodiment, the zinc layer is selected from the group consisting of zinc plating, zinc nickel alloys, zinc cobalt alloys, zinc aluminum alloys, and mixtures thereof.

[0035] A surface treatment layer 16 is bonded to the zinc layer 14. Any suitable surface treatment layer 16 may be used. However, in the preferred embodiment, surface treatment layer 16 is selected from the group consisting of a zinc/aluminum/rare earth alloy, phosphate, chromate, and mixtures thereof.

[0036] The phosphate and/or chromate may be applied in any suitable manner. In the preferred embodiment, a hot phosphoric acid is used. Without being bound to any theory, it is believed that this acid etches into the metal surface, leaving a phosphate crystalline structure in the metal, which structure aids in subsequent adhesion of polymeric materials. Over electroplating, a wet bath chromate may be used, after which the metal is rinsed well. Chromium oxides are left on the metal, which are believed to aid in corrosion resistance, and which, although optional, are further believed to enhance the advantageous properties of the phosphate. Over the zinc/aluminum/rare earth alloy treatment, a dry chromate may be used which does not require subsequent rinsing.

[0037] The zinc/aluminum/rare earth alloy used is preferably GALFAN, commercially available from Eastern Alloys, Inc. in Maybrook, N.Y.; licensed from the International Lead Zinc Research Organization, Inc. located in New York, N.Y.; and described in U.S. Pat. No. 4,448,748, discussed more fully above. Particularly preferred is the combination of the GALFAN with the phosphate, or the GALFAN with the phosphate and chromate. Without being bound to any theory, it is believed that either of these two combinations for the surface treatment layer 16 are particularly advantageous and useful in the present invention.

[0038] It is to be understood that the zinc layer 14 and/or surface treatment layer 16 may be optional components of the present invention. Various polymeric compositions may be applied directly to a bare metal surface, especially for decorative purposes. Further, it is contemplated that various polymeric compounds and/or blends, including those containing suitable ionomers, may substantially bond to an untreated metal surface, thereby giving the numerous corrosion and abrasion resistant properties enumerated herein.

[0039] A primer 17 is applied beneath the polymeric layer(s), to the outer surface of the metal tube 12 having any desired pretreatment/coatings thereon. The primer may be any suitable primer which would promote adhesion of the polymeric layer(s) to the metal tube 12, even under aggressively corrosive conditions. In the preferred embodiment, the primer is Nylon Primer 2BME45451, commercially available from Akzo Nobel Co. A product data sheet for this material is appended hereto as Table A. An MSDS for this material is appended hereto as Table B.

[0040] A first polymeric layer 18 is bonded to the surface treatment layer 16. It is to be understood that any suitable polymeric layer may be used which suitably bonds to the surface treatment layer 16, and in turn, suitably bonds to subsequent polymeric layers, if any. In the preferred embodiment, the first polymeric layer 18 is selected from the group consisting of a thermoplastic elastomer, an ionomer, a nylon, a fluoropolymer, and mixtures thereof.

[0041] A second polymeric layer 22 may be bonded to the first polymeric layer 18 (not shown). It is to be understood that any suitable polymeric layer may be used which suitably bonds to first layer 18, and which provides suitable mechanical and chemical corrosion resistance. In the preferred embodiment, the second polymeric layer 22 is selected from the group consisting of a nylon, a thermoplastic elastomer, a fluoropolymer, and mixtures thereof.

[0042] The multi-layer tube 10 may further comprise a third polymeric layer 20 interposed between, and bonded to the first and second polymeric layers. It is to be understood that any suitable polymeric layer may be used which suitably bonds to first layer 18 and to the second layer 22 and which may optionally provide suitable cushioning, if desired. In the preferred embodiment, the third polymeric layer 20 is selected from the group consisting of an ionomer, a nylon, ethylene vinyl alcohol, a polyolefin, and mixtures thereof.

[0043] It is to be understood that any or all of the three-layers, 18, 22, 20 may include multiple sublayers (not shown). Further, it is to be understood that each of the layers and/or sublayers may be formed from a single compound listed in the relevant group, or from a combination thereof. Still further, it is to be understood that each-of the layers/sublayers may be comprised of the same material. The thickness of the combined polymer layers can be as little as 0.004 inch, and can be made even thinner. Successful coatings have been applied having combined polymer layer thicknesses of 0.004 inch, 0.005 inch, 0.006 inch, 0.007 inch, 0.009 inch and 0.010 inch, with a preferred range of 0.005 inch to 0.010 inch.

[0044] Examples of suitable compounds for each of the layers will be described hereinafter.

[0045] One of the advantages of the present invention is that a chemical or mechanical bond is formed between all the layers. It is believed that good bonding prevents moisture buildup beneath the layers, which buildup greatly increases the likelihood of corrosion.

[0046] The thermoplastic elastomers which can successfully be employed in the tubing 10 of the present invention are commercially available under tradenames such as: SANTOPRENE®, a thermoplastic rubber commercially available from Advanced Elastomer Systems of St. Louis, Mo.; KRATON®, a thermoplastic rubber composed of a styrene-ethylene/butylene-styrene block copolymer commercially available from Shell Chemical Co. of Houston, Tex.; SARLINK, an oil resistant thermoplastic commercially available from Novacor Chemicals of Leominster, Mass.; and VICHEM, a family of polyvinyl chloride compounds commercially available from Vichem Corporation of Allendale, Mich.

[0047] Of the various thermoplastic elastomers suitable in the present invention, HYTREL is a preferred compound. HYTREL is a thermoplastic elastomer commercially available from E.I. DuPont de Nemours & Co., located in Wilmington, Del. It is contemplated that any grade of HYTREL is useful in the present invention, preferably such a grade which possesses a Shore D Hardness ranging between about 40 and about 55, and still more preferably, one having a Shore D Hardness of about 40. Grades having D40 (Shore) hardness include G-4074; G-4078; 4056; and 4059 FG.

[0048] A suitable nylon material includes 12 carbon block polyamides, 11 carbon block polyamides, and zinc chloride resistant 6 carbon block polyamides. Of these, Nylon 12 and zinc chloride resistant Nylon 6 are preferred. The 6-carbon block polyamide or Nylon 6 either inherently exhibits zinc chloride resistance or contains sufficient quantities of modifying agents to impart a level of zinc chloride resistance greater than or equal to that required by Performance Requirement 9.6 as outlined in SAE Standard J844 (Revised June 1990), i.e. non-reactivity after 200 hour immersion in a 50% by weight zinc chloride solution. The Nylon 6 can also be modified with various plasticizers, flame retardants and the like in manners which would be known to one reasonably skilled in the art.

[0049] Most preferred as the polymeric material of the first and second polymeric layers is Nylon 12. Preferably, the Nylon 12 of choice is VESTAMID X 7377, commercially available from Huls-Creanova. A product data sheet for this material is appended hereto as Table C; and an MSDS is appended hereto as Table D. This material has lower viscosity and lower molecular weight, thus advantageously allowing for higher line speeds during multi-layer tubing 10 production.

[0050] Suitable fluoropolymers may include polyvinylidine fluoride, polyvinyl fluoride, ethylene tetrafluoroethylene, and mixtures thereof. The material can also be a graft copolymer of the preceding materials together with a fluorine-containing polymer such as copolymers of vinylidine fluoride and chlorotrifluoroethane. Suitable material employed may contain between about 60% and about 80% by weight polyvinylidine difluoride. Materials so formed have a melting point between about 200° C. and about 220° C. and a molding temperature between about 210° C. and about 230° C. Further suitable fluoropolymers include: a copolymer of a vinyl fluoride and chlorotrifluoroethylene, the vinyl fluoride material selected from the group consisting of polyvinylidine fluoride, polyvinyl fluoride, and mixtures thereof; a copolymer of vinyl fluoride material and ethylene tetrafluoroethylene; a non-fluorinated elastomer, and mixtures thereof. The material of choice exhibits an affinity to polymers employed in the first 18 second 22 or third 20 layers, such as, for example, Nylon 12 or Nylon 6. Some suitable fluoropolymers are commercially available under the tradename “ADEFLON A” from Atochem Inc. elf Aquitaine Group of Philadelphia, Pa.

[0051] Other suitable materials, especially useful in an interposed layer 20 or in sublayers of any of the three layers 18, 22, 20 include ethylene vinyl alcohol, selected from the group consisting of copolymers of substituted or unsubstituted alkenes having less than four carbon atoms and vinyl alcohol, and mixtures thereof. Also useful are copolymers of alkenes having less than four carbon atoms and vinyl acetate. Also suitable are polyolefin compounds, including, but not limited to polyethylene, low density polyethylene, and polypropylene.

[0052] The multi-layer tube 10 may have the first polymeric layer 18 consisting essentially of an ionomer and a nylon, such as ethylene methacrylic acid copolymer—partial metal salt, and Nylon 12. This may be in any suitable percent composition and may have any additional suitable additives. In the preferred embodiment, this percent composition ratio is between about 10% and about 70% ethylene methacrylic acid copolymer—partial metal salt, and between about 90% and about 30% Nylon 12. More preferably, this percent composition ratio is between about 40% and about 60% ethylene methacrylic acid copolymer—partial metal salt, and between about 60% and about 40% Nylon 12.

[0053] The second polymeric layer 22 may consist essentially of a nylon. In the preferred embodiment, this layer is Nylon 12.

[0054] Third layer 20 may be any of the suitable materials listed hereinabove. In an alternate preferred embodiment, this third layer 20 may be a “regrind” or “recycle” of the suitable polymeric materials enumerated above. It is to be understood that the definition of “regrind” or “recycled” material as used herein comprises any generation of “regrind” or “recycled” material which substantially possesses between about 65% and about 95% (or higher) of each of the cold temperature impact, viscosity and elongation properties of the virgin material; more preferably, possesses between about 80% and 95%, and still more preferably possesses between about 90% and 95%. However, it is to be understood that any suitable regrind which performs in the desired manner in the present invention is contemplated and may successfully be used herein. If such a “regrind” is used as third layer 20, it is preferred that a virgin material be used as second (outer) layer 22.

[0055] The process for applying the primer is described and shown in FIGS. 1-3, 5 and 6. This process is an airless spray system, having a closed atmosphere. This system provides a uniform coating of primer. Further, it is environmentally friendly in that virtually no noxious fumes escape to the atmosphere, virtually all the primer is captured and reused, and since it is a closed atmosphere, the amount of solvent used is reduced—the operator does not need to keep adding solvent since there is little appreciable solvent loss. Negative pressure in the paint booth prevents escape of VOCs into the atmosphere. A chemical is added into the water scrubber which causes VOCs to coagulate and rise to the surface, which coagulants may then be skimmed off the top and disposed of in an environmentally safe manner.

[0056] To further illustrate the composition, the following examples are given. It is to be understood that these examples are provided for illustrative purposes and are not to be construed as limiting the scope of the present invention.

EXAMPLE I

[0057] A {fraction (3/16)} inch brazed steel tube had a GALFAN coating of 78 g/m2 and a phosphate coating of 120-250 mg/ft2, with an additional chromate wash, with the chromate wash having essentially no remaining weight. A primer commercially available from Akzo Nobel under the tradename Nylon Primer 2BME45451 was applied to the tube having the GALFAN/phosphate/chromate as described immediately above. The primer was applied by the airless spray system as described further hereinabove. Applied thereto were two layers of Nylon 12 (VESTAMID X7377) having a total thickness between about 0.005 inch to 0.010 inch.

EXAMPLE II

[0058] The tubing of Example I was cut into 6 tube specimens and was subjected to various tests. The tests are described in Table E appended hereto. The test results are described in Table F appended hereto.

EXAMPLE III

[0059] The tubing of Example I was cut into 3 tube specimens and was subjected to various tests. The tests are described in Table E appended hereto. The test results are described in Table G appended hereto.

TABLE A
AKZO NOBEL
                                 TUBE
                                 COATINGS
                                 Product Data Sheet
Date: August 13, 1998            PRODUCT DESCRIPTION
Product Name: Nylon Primer       Adhesion promoting primer for
                                 under Nylon over Galfan tubing.
                                 The primer improves the adhesion,
                                 flexibility and corrosion of the
                                 Nylon coating.
Akzo Nobel Code: 2BME45451
Prepared For: ITT Automotive
PHYSICAL PROPERTIES
Wt./Gal.: 9.46 = 0.3             APPLICATION PROPERTIES
Theor. Solids by WT. % 53.6% ± 3 Equipment: Spray
Theor. Solids by Vol. % 34.7% ± 3 Substrate: Galfan
Viscosity: 25-30 sec @ 80° F.    Primer:
Viscometer: #4 Zahn              Surface Preparation:
                                 Bondenta 1421
Gloss: Medium @ 60°              Application Viscosity:
@ 35°                            15-20 sec #4 Ford cup
                                 Reducer: PM Acetate
Hardness: F Turquoise Min        Recommended Film Thickness:
Cure Test: 50 −MEK rubs          Wet: 0.2-0.5 mils
Forming Test: 3T min             Dry: 0.15+−0.05 mils
                                 Bake Schedule: Induction curing
                                 Setting for desired PMT ° F.
                                 Peak Metal Temperature:
                                 450-550° F.
Remarks:

[0060]

TABLE B
MATERIAL SAFETY DATA SHEET
DATE PRINTED: 12/15/96	$45451	IPL #	TC#20015
SECTION 1
MANUFACTURERS NAME:
	AKZO COATINGS INC.
STREET ADDRESS:
	1845 MAXWELL
	TROY, MI 48084
EMERGENCY TELEPHONE NUMBERS:
	8:00 AM-4:45 PM (810) 637-0400
	AFTER HOURS (810) 637-5210
PRODUCT CLASS:	MANUFACTURER’S CODE IDENTIFICATION:
	PHENOLIC COATING	28ME45451
TRADE NAME:
	NYLON PRIMER
SECTION II - HAZARDOUS INGREDIENTS
				*	TLV-TWA	*	PEL-TWA
		*PCT*		PPM	*	PPM	*	*Vapor
HAZARDOUS INGREDIENTS:	C.A.S. No.	*By Wt*	*	MG/W3*	*	MG/W3	*	Press
M-BUTYL ALCOHOL	71-36-3*35-50*Skin		*	50.0000	*	100.0000	*	4.4
1-BUTANOL	*  *	*		152.0000	*	300.0000	*
CRESTYLIC ACID (ISOMERS	1319-77-3*	<5 Skin	*	5.0000		5.0000	*	.9
AND MIXTURE
CORESOL	*  *	*		22.0000	*	22.0000	*
FORMALDEHYDE	50-00-0*	<.5*	*	.3000	*	.7300	*	0 9.5
	*	*	*	.3700	*	—	*
PHENOL	106-95-2*	<5*Skin	*	5.0000	*	5.0000	*	NA
CARBOLIC ACID	*	*	*	19.0000	*	19.0000	*
PROPYLENE GLYCOL METHYL	108-65-6* 5-20	*	*	—	*	—	*	3.9
ETHER ACETATE
PM ACETATE	*	*	*	—	*	—	*
TITANIUM DIOXIDE	13463-67-7*15-30		*	*—	*	—	*	NA
	*	*	*	10.0000	*	15.0000	*
SECTION III - PHYSICAL DATA
BOILING RANGE:	VAPOR DENSITY VS. AIR:
243-405 DEG. F.	HEAVIER THAN AIR
EVAPORATION RATE VS. ETHER:
SLOWER
PERCENT VOLATILE BY VOLUME:	WEIGHT PER GALLON:
62.3	9.46 LBS.

[0061]

TABLE C
Creanova
•Engineering Plastics
January 1998
VESTAMID ® coated steel tubing processing recommendations
Material
VESTAMID X 1377 black 9.7504 (lower viscosity): 270-230° C.
(410-445° F.) melt temperature
VESTAMID LX 9001 black 9.7504 (higher viscosity): 215-240° C.
(420-465° F.) melt temperature
Tubing treatment
Chromate application:
as thin as possible - because the chromate layer has no mechanical strength
as thick as necessary - to be sure that the whole surface is treated
(additional primers or conditioning are not necessary)
Tubing temperature
230-280° C. (446-535° F.) via induction heating
(blistering in the plastic must be avoided)
Cross head conditions
Draw down ratio of 1.5:1 to 2:1
A vacuum should be applied between the steel tube and the PA 12
to enhance the application of the melt to the steel.
Downstream conditions
Distance between cross head die and water tank may vary.
The outer PA 12 surface and the adhesion of the PA 12 to steel
may both be contingent on this distance, in relation to line
speed & temperatures.
Additional items of note
The cross head application of PA 12 to the tube is recommended
as soon as possible after the tubing is chromated. (Optimum would be to
have the chromate treatment in line with the extrusion coating)

[0062]

TABLE D
CRENOVA INC.	24 Hour Emergency:
	Number: 800-424-9300
	24 Hour CHEMTREC
	Number: 800-424-9300
Approval Date: November 8, 1996	Cust: 30158042
Print Date: February 16, 1999	MSDS Number: 1300167 01-08
1. CHEMICAL PRODUCT AND COMPANY IDENTIFICATION
Product Name: VESTAMID - X 7377 BLACK 9.7504
Supplier/Manufacturer:
CRENOVA Inc.
Turner Place, Box 365
Piscataway, NJ 08855
Environmental & Regulatory Affairs,
Information Number: 908-981-5016
2. COMPOSITION/INFORMATION ON INGREDIENTS
This product does not contain any components considered to be health
hazards under the OSHA Hazard Communication Standard 29 CFR
1910.1200 or under the WHMIS Controlled Product Regulations
in Canada.
3. HAZARDS IDENTIFICATION
***EMERGENCY OVERVIEW***
Fumes from hot processing may be irritating to eyes and respiratory tract.
POTENTIAL HEALTH EFFECTS
Eye Contact:
Fumes from hot processing may cause eye irritation.
Skin Contact:
No hazard expected in normal use.
Inhalation:
Fumes from hot processing may cause irritation.
Ingestion:
Not applicable; not an expected route of exposure.
4. FIRST AID MEASURES
FIRST AID
Eye Contact:
In case of contact, immediately flush eyes with plenty of water.
Obtain medical attention if irritation develops or persists. 5.
Skin Contact:
Wash with water. For hot product, immediately immerse or flush the
affected area with large amounts of cold water to dissipate heat.
Cover with clean cotton sheeting or gauze and get prompt medical
attention. No attempt should be made to remove material from skin
or to remove contaminate clothing as the damaged flesh can be
easily torn.
Inhalation:
In case of exposure to fumes from hot processing, remove victim
to fresh air. If not breathing, give CPR. If breathing is
difficult, give oxygen. Get medical attention.
Ingestion:
Not applicable: not an expected route of exposure.
5. FIRE FIGHTING MEASURES
Flash point: not applicable  Lower Explosive Limit:  Not applicable
Flash point Method: not applicable
Upper Explosive Limit:  Not applicable
OSHA flammability Classification: None  Autoignition
Temperature: >350
Other Flammable Properties:
Dusts at sufficient concentrations can form explosive mixtures with air.
Extinguishing Media:
Use water spray or fog, foam, dry chemical or CO2.
Fire Fighting Procedures:
As in any fire, wear self-contained positive-pressure breathing
apparatus, (MSHA/NIOSH approved or equivalent) and full protective
gear.
6. ACCIDENTAL RELEASE MEASURES
Steps to be taken in case meterial is released or spilled:
Allow molten material to solidity and scrape up. Collect material and
place in a disposal container. Obey relevant local, state, provincial
and federal laws and regulations. Do not contaminate any lakes,
streams, ponds, groundwater or soil.
7. HANDLING AND STORAGE
Handling:
Use with adequate ventilation. Avoid breathing vapors from heated
material.
8. EXPOSURE CONTROLS/PERSONAL PROTECTION
This product does not contain any components considered to
be health hazards under the OSHA Hazard Communication Standard
29 CFR 1910.1200 or under the WHMIS Controlled Product
Regulations in Canada.
Engineering Controls:
Use adequate ventilation.
Respiratory Protection:
In case of exposure to fumes in hot processing, use appropriate
NIOSH-approved respiratory protective equipment.
Eye Protection:
Wear safety glasses with side shields.
Skin Protection:
Use impermeable gloves.
Other Protective Equipment:
To identify additional Personal Protective Equipment (PPE) requirements,
it is recommended that a hazard assessment in accordance with the
OSHA PPE Standard (29CFR1910.132) be conducted before using this
product.
9. PHYSICAL AND CHEMICAL PROPERTIES
	Vapor Pressure	Not applicable
	Vapor Density (Air = 1)	Not applicable
	Specific Gravity	1.0-1.2″
	Boiling Point	Not available
	Melting Point	80 to 220° C.
	pH	Not available
	Evaporation Rate	Not applicable
Other Properties:
Granulate. Odorless. Solubility in water: Negligible. (*) = This
information applies to a group of products. The data for this specific
grade can be obtained form the Product Information Sheet.
10. STABILITY AND REACTIVITY
Stability:
This product is stable under normal storage conditions.
Hazardous Polymerization:
Will not occur under normal conditions.
Conditions to Avoid:
Operations that create dust.
11. TOXICOLOGICAL PROPERTIES
Other Toxicological Information:
The toxicological properties of this product have not been
fully investigated.
12. ECOLOGICAL INFORMATION
Ecological Information:
No information available.
13. DISPOSAL CONSIDERATIONS
Disposal Method:
Incinerate. Follow all federal, state, and local regulations.
14. TRANSPORTATION INFORMATION
U.S. DOT Transport Information
Proper Shipping Name: Not regulated
15. REGULATORY INFORMATION
This product contains the following non-hazardous components:
	CAS Number	wt. %
Azacyclotridecan-2-one, homopolymer	025038-74-8	94
NJTSR No. 5605700001-5190P	Trade Secret	5
U.S. Federal Regulations
OSHA:
This document has been prepared in accordance with the MSDS
requirements of the OSHA Hazard Communication Standard.
Clean Air Act Section 112:
This product contains the following componenets listed as Hazardous Air
Pollutants:
None.
This product contains the following components listed as Extremely
Hazardous Air Pollutants:
None.
SARA Section 311/312:
Hazard Classification: None
SARA Section 313:
This product contains the following substances subject to the reporting
requirements of Section 313 of Title III of the Superfund Amendments
and Reauthorization Act of 1986 and 40 CFR Part 372:
None
TSCA:
This product or its components are listed in or exempt from TSCA
inventory requirements.
This product contains the following non-proprietary substances subject
to export notification under Section 12(b) of TSCA:
None
State Regulations
New Jersey:
This product contains the following non-hazardous components subject to
disclosure under New Jersey Right-To-Know legislation:
		CAS Number
	Azacyclotridecan-2-one, homopolymer	025038-74-8
	NJTSR No. 56705700001-5190P	Trade Secret
Pennsylvania:
This product contains the following non-hazardous components subject
to disclosure under Pennsylvania Right-To-Know legislation:
		CAS Number
	Azacyclotridecan-2-one, homopolymer	025038-74-8
	NJTSR No. 56705700001-5190P	Trade Secret
Massachusetts:
This product contains the following substances on the Massachusetts
Substance List:
None
California (Proposition 65):
This product contains the following substances known to the State of
California to cause adverse reproductive effects:
None
International Regulations
Summary of International chemical Inventory Status
	Canada	On inventory
	Europe	On inventory
	South Korea	Not on inventory
	Australia	On inventory
16. OTHER INFORMATION
HMIS Ratings:	Health - 1  Flammability - 1  Reactivity - 0
Ratings Key:	4 = Highest hazard, 0 = Lowest hazard,
	* = Chronic health hazard, N = No rating for powders
NFPA Ratings:	Health - 1  Flammability - 1  Reactivity - 0
Ratings Key:	4 = Highest hazard, 0 = Lowest hazard,
	N = Nor rating for powders
Key to abbreviations used:
NA	Not applicable
NAV	Not available
NE	Not established
NJTSR No.	New Jersey Trade Secret Registry Number
®	Registered Trademark owned by or licensed
	to CREANOVA Inc.,
	CREANOVA Canada Inc., CREANOVA Spezialchemie
	GmbH, or Rôhm GmbH.
TM	Trademark owned by or licensed to CREANOVA
	Inc., CREANOVA
	Canada Inc., CREANOVA Spezialchemie GmbH, or
	Rôhm GmbH.
Revision Summary:
The following MSDS sections were revised since the previous version
March 17, 1995:
Color number added to name
Sections 5, 9 and 10: General dust precautions added.

[0063]

TABLE B
COATINGS FOR STEEL TUBING
1.0 GENERAL
1.1 Purpose of the Standard
This standard outlines the requirements for coatings applied to the
outside and tide diameter of steel tubing. The coatings are applied
to the outside diameters of double wall brazed thing (MS-1806) or
single wail welded tubing (MS-3236). This standard defines the
coating requirement for cases requiring greater internal corrosion
resistance than carbon steel aril approaching the corrosion
resistance of austeninc stainless steel.
1.2 Purpose of The Process
The purpose of the process is to define the parameters of material
application and thickness to achieve the corrosion resistance required.
A classification of the various coatings is described in Table 1.
Coating I offers superior corrosion and abrasion resistance over
Coatings II. Coatings I and II shows improved corrosion resistance
over Coatings III, IV and V and VI. Both coatings V and VI
containing Lead Tin are being phased out over the next few years.
Coating V used in non-abrasive areas of some passenger car
platforms for brake line applications and for fuel lines in
passenger cars, jeep and truck. Coating V, a duplex coating
of zinc rich with the heavier Tin Lead Coating, is often used
with a mechanical abrasion resistant zinc coated (P3-77) steel wire
cover or other protective covering for brake lines. The heavier Lead
Tin Coating - 49 g/m2 for brake lines, for fuel lines -
18 g/m2 are being replaced by hot dipped zinc aluminum alloy
or electroplated zinc. A comparison summary of the various corrosion
resistant properties and coating thicknesses are shown in Table 2.
Aluminum coated armor wire with a minimum coating weight of
60 g/m2 per ASTM A 764 Type A is used as a further protection
for stone abrasion. Armor is expected to be superior to shrink wrap
for use in abrasion resistance protection for Coating I should it be
required. The melt point of Coating I Polyamide 12 coating is
approximately 177 Degrees C. (350 Degrees F.). The general operating
temperature for Nylon 12 Is 149 Degrees C. (300 Degrees F.). The
safe operating temperature for the zinc aluminum alloy is approximately
250 Degrees C. (482 Degrees F.). The aluminum rich coating is cured at
254 degrees C. to 275 degrees C. (490 degrees F. to 527 degrees F.).
The polyvinylidene or poly vinyl fluoride coating is cured at 240
degrees C. (464 degrees F.). The zinc chromate coating is cured at
190 degrees C. (375 degrees F.).

[0064]

TABLE 1
CLASSIFICATION OF VARIOUS
EXTERNAL COATINGS AVAILABLE
(See para 1.3.1-Designation Codes)
COATING	CODE	DESCRIPTION
I	LZ	Hot dipped zinc alloy coating followed by an
		extruded polyamide Nylon 12 coating.
II	PE, VE	Electroplated zinc coating or hot dipped
		zinc alloy coating, followed by a poly vinyl
		fluoride or polyvinylidene fluoride coating
III	AZ	Hot dipped zinc alloy coating followed by an
		aluminum rich-organic coating
IV	NZ	Hot dipped zinc alloy
V	CT, CH	A duplex coating consisting of a led on alloy
		coating followed by an organic coating containing
		chromates and zinc particles formerly PS-7069
VI	NT, NH	A hot dipped lead tin coating formerly PS 954

[0065]

TABLE 2
SUMMARY AND COMPARISON OF VARIOUS
EXTERNAL COATINGS AND THEIR
CORROSION REQUIREMENTS
COATING	CODE	DESCRIPTION	CORROSION RESISTANCE	THICKNESS OUTER/INNER
I	LZ	Extruded polyamide	Paragraph 5.1	Paragraph 4.1 Nylon:
		Nylon 12 polyamide	A) 2000 hours knife cut salt spray	0.170 mm (0.0067 inch) minimum per
		over hot dipped zinc	ASTM B117. No lifting or	ASTM B 487.
		aluminum alloy	delamination of coating. Red rust is	4.2B
		coating	allowed only at knife cut.	Zinc 5% Aluminum alloy
				5.2 microns (0.0002 inch), 36
			B) Fuel Soak Testing 500 hours	g/meter squared minimum per ASTM
			ascribed and not scribed per 5.1.B.	A 90.
			C) Gravelometer -18 Deg C. (0 Deg
			F.) SAE J400 5 pints, 1500 hours
			ASTM B-117. No lifting or
			delamination of coating. Red rust is
			allowed only at gravel impacted area;
			5% of impacted areas, maximum.
			D) Gravelometer and cyclic salt
			spray ASTM B-117 5, 5, 5, 5, pints,
			400 hours. No lifting or
			delamination of coating. Red rust is
			allowed only at gravel impacted area;
			10% of the impacted areas,
			maximum.
			E) 170 cycles burst 13,789 kPa (2000
			psi) minimum for Brakelines,
			Functional for fuel lines, power
			steering and transmission ad cooler
			lines.
II	PE, VE	Polyvinyl fluoride or	Paragraph 5.2	Paragraph 4.2 B and C Fluoride
		polyvinylidene fluoride	A) 400 hours knife cut salt spray	coating 10 microns (.0004 inch
		coating over	ASTM B-117	minimum per ASTM B 487:
		electroplated zinc.		Electroplated and 25 microns (0.001
			B) Gravelometer-18 Deg C. (0 Deg	inch) minimum for MS-1808 and 13
			F.) 1 pint 1000 hours no red rust at	microns (.0005 inch for MS 3235,
			gravel impacted areas	minimum coating 180 g/meter squared
				and 90 g/meter squared per ASTM A
				90 FOR ms-1806 and MS-3235
				respectively.
II	PZ, VZ	Polyvinyl fluoride or	Paragraph 5.2	Paragraph 4.2C
		polyvinylidene fluoride	A) 400 hours knife cut salt spray	A Fluoride coating 10 micros (.0004
		coating over hot	ASTM B117	Inch) minimum per ASTM B 487.
		dipped zinc aluminum		4.2B Zinc aluminum alloy
		alloy.	B) Gravelometer-18 Deg C. (0 Deg F.)	5.2 microns (.0002 Inch), 36
			SAE J400 1 pint and salt spray per	g/meter squared per minimum
			ASTM B-117 shall meet 1000 hours	per ASTM A 90
			with no red rust.
III	AZ	Aluminum Rich over	Requirements to Paragraph	Paragraph 4.3C
		hot dipped zinc	5.2A, B above.	Aluminum rich coating 8 g/meter
		aluminum alloy	Paragraph 5.2C	squared (.026 oz/square foot).
			360 hours salt spray per ASTM B-	Paragraph 4.2B Zinc aluminum alloy
			117 no more than 1% red rust over	5.2 microns (.0002 inch), 36 g/meter
			any 25.4 mm (1 inch) length	squared per minimum per ASTM A 90
			compared to ASTM D 610, Plate 6
IV	NZ	Hot dipped zinc	Paragraph 52C	Paragraph 4.2B
		aluminum alloy	360 hours salt spray per ASTM B-	5.2 microns (.0002 inch) minimum
			117 no more than 1% red rust over	per ASTM B 487 Coating coverage
			any 25.4 mm (1 inch) length	minimum 36 g/meter squared per
			compared to ASTM D 610, Plate 6	ASTM A 90
V	CT, CH	Zinc chromate over	Paragraph 5.3A	Paragraph 4.4D
		hot dipped lead tin	200 hours resistance to red rust and	15 g/meter squared (05. Oz/square
		alloy	shall show no more than 1 base	foot) minimum organic zinc chromate
			metal corrosion 1.5 mm (.080 inch)	Paragraph 4.4B.
			in diameter or larger in any area	31 g/meter squared led-tin over MS-
			500 square millimeter (.77 square	1806 tubing or 18 g/meter squared
			inch) when tested per ASTM B.117	(.06 oz/square foot) per ASTM A 309
				over MS-3225 tubing.
VI	NT, NH	Hot dipped lead tin	No requirements.	Paragraph 4.5
		alloy	Less than 24 hours in salt spray to	49 g/meter squared lead-tin (0.16
			red rust per ASTM B 117	oz/square foot) per LP-461H-102
			(Engineering Reference	applied over MS-1806 tubing and 18
			Characteristic).	g/meter squared (0.06 oz/square foot)
				per LP-461H-102 applied to MS-3235,
				ASTM A309.
1.3 COVERAGE OF THIS STANDARD
This standard describes the methods for corrosion protection of tubing used for automotive brake and fuel lines, transmission oil cooler
lines, and power steering lines. The engineering coating designation codes, process for applying the coatings, requirements of
appearance, coating weight and thickness of the individual coatings, and the corrosion resistance from the combination of coatings are
defined.
1.3.1 COATING DESIGNATION CODES***
Any requirements shown on the part drawing shall take precedence over the requirements specified in this standard. The following codes
shall be applied to the engineering part drawing.
Coating Designation PS-8688 XY:
X - First Letter, Outer Coating;
P- Polyvinyl Fluoride - PVF
V-Polyvinylidene Fluoride - PYDF
A-Aluminum Rich Organic
C-Zinc Rich, Chromate Organic
N-No Top Coating
L-Nylon 12 Polyomide
Y-Second Letter, Inner Coating:
E-Electroplated Zinc-
Z-Zinc 5% Aluminum Alloy-Hot Dipped
T-Lead-Tin Alloy Hot Dipped-18 g/m2
H-Lead-Tin Alloy Hot Dipped-49 g/m2
Z-Third letter, Coating applied to Inside Diameter of Single Wall Electric Welded Tubing (Third letter is only used to specify requirements
for ID coating, such as nickel plated coating. When a third letter is not used, an ID coating is not used, an ID coating is not specified).
N-Nickel Electroplate ID Tubing, 3.8 microns minimum (0.000 150 Inch)
U-Uncoated
C-Copper Electroplate, 3.3 microns minimum (0.000150 inch) on both surfaces
For example:
PS-8688 AZ: Designates an aluminum rich coating applied to a zinc aluminum alloy coated tubing.
PS-8688 LZ: Designates an extruded Nylon 12 polyamide coating applied to a zinc aluminum coated tubing.
PS-8688 NH: Designates a Terne coat over the tubing and no topcoat over the Terne. Coating weight of lead - tin alloy to 49 g/m2.
PS-8688 PZ: Designates a polyvinyl fluoride coating applied over a zinc aluminum alloy coating tubing.
PS-8688 CH: Designates zinc rich organic, chromate coating applied to a lead-tin alloy coating. The coating weight for the lead-tin is 49
g/m2.
PS-8688 LZN: Designates an extruded Nylon 12 polyamide coating applied to a zinc aluminum coated tubing. The ID of the tubing is
coated with a deposit of 3.8 microns minimum of nickel electroplate.
PS-8688 PEN: Designates a Polyvinyl Fluoride over electroplated zinc on the outside diameter and 3.8 microns minimum of electroplated
nickel applied to the inside diameter of the tubing.
2.0 COATING PROCEDURES***
The processes utilized in this specification are referenced here and in the sections referenced.
Zinc-Electroplated (PS-79) per Paragraph 3.1
95% Zinc-5% aluminum alloy hot dip per Paragraph 3.1 (Table 3, Paragraph 3.2)
Dichromate Conversion Treatment (PS-1207) per Paragraph 3.3
Fluoride Coating per Paragraph 3.4
Nylon - Nylon 12 Polyamide per Paragraph 3.5
Nickel Electroplate (ASTM B639-90) per Paragraph 3.6
Aluminum Rich organic coating per Paragraph 3.7
Organic coating containing chromates and zinc particles per Paragraph 3.8
Lead - tin alloy coating per Paragraph 3.9
Appearance, Coating Weight, and Thickness of the Coatings and defined in the section 4.
Corrosion is specified in section 5.
3.0 PROCESS
3.1 ZINC OR ZINC ALUMINUM ALLOY COATING PROCESS
Zinc electroplating shall be in accordance PS-79. The zinc aluminum alloy hot dip coating process shall use a 95% zinc - 5% aluminum
alloy per paragraph 3.2 (Table 3).
3.2 ZINC-ALUMINUM ALLOY

[0066]

TABLE 3
ZINC ALUMINUM ALLOY COATING CHEMISTRY
(INCOMING INGOT), PERCENT)
Aluminum      4.7-5.2
Lanthanum     0.02-0.05
Cartum        0.01-0.04
Others - each 0.005 max.
Zinc          Remainder
3.3 CHROMATE CONVERSION TREATMENT
Following the zinc electroplating coating Process 3.1 the surface
shall be olive drab chromate chemical conversion treated per PS-1207.
Following the zinc aluminum alloy coating process 3.2 an optional
chromate chemical treatment per PS-1207 is permissible.
3.4 FLUORIDE COATINGS
A fluoride coating shall be applied to the outside diameter of the
tubing. Either the polyvinyl fluoride or the polyvinylidene fluoride
coating is to be used as a top coating. The top coatings
are applied over zinc or zinc aluminum alloy coatings.
3.5 NYLON COATING***
The nylon polyamide 12 coating shall be applied to the outside
diameter of the tubing. It shall be used as the top coating. The Nylon 12
is extruded over the zinc aluminum alloy Paragraph 3.2 (Table 3)
coated tubing. Prior to the extrusion of Nylon 13, an application of the
primer shall be used to promote adhesion and corrosion resistance
of the tubing.
3.6 NICKEL COATING***
The nickel coating is used for LZN or PEN or AZN. The nickel
coating shall be applied to the inside diameter of the tubing. The nickel
coating is electro deposited per ASTM B689-90 to the low carbon steel
substrate. The nickel coating shall be free from pits or blisters.
The strip shall withstand a 180 degrees bend over a radius equal to twice
the thickness of the strip and return without showing any
peeling or lifting of the nickel when examined under a 10X magnification.
Minimum thickness is 3.8 microns (0.000150 inch) free or
diffused Nickel. Nickel reflows over the resistance tube weld to maintain
exceptional corrosion resistance at the inside diameter.
3.7 ALUMINUM - RICH ORGANIC COATING
The aluminum rich organic coating shall be applied to the outside diameter
of the zinc aluminum alloy Paragraph 3.2 (Table 3) coated
tubing. The tubing shall be baked to cure the aluminum rich organic
coating.
3.8 ORGANIC ZINC CHROMATE COATING PROCESS
The coating consisting of zinc particles, chromates, and organic
material shall be applied to the outside diameter of the tubing. The
tubing shall be baked to cure this organic coating to a coverage of
Paragraph 4.4D.
3.9 LEAD-TIN ALLOY COATING PROCESS
The coating shall be applied to the outside diameter of the tubing.
The tubing shall be cleaned and immersed in a fluxing solution. Then
the tubing shall be immersed in a molten bath of lead-tin alloy which
contains a minimum of the percent an as defined in Paragraph
4.4.C. The coated tubing shall be washed as required to remove any
residual flux.
4.0 QUALITY (APPEARANCE, COATING WEIGHT, AND
THICKNESS OF COATINGS) <S>***
4.1 Nylon 12 Polyamide Coating over Zinc-Aluminum Alloy or Nylon 12
Polyamide coating over Zinc-Aluminum coating applied to
Nickel ID coated tubing.
A. Color shall be black unless otherwise specified.
B. Thickness and coating coverage of zinc-alloy coating paragraph 4.2.B.
The minimum coating coverage of the nickel ID coating
per paragraph 3.6.
C. The minimum coating coverage of the Nylon 12 polyamide coating is
0.17 mm (0.0067 inch) minimum and shall meet the OD
requirements of Table 4.

[0067]

TABLE 4
MAXIMUM ALLOWABLE OUTER DIAMETER FOR THE COATED
TUBE FOR A GIVEN TUBE SIZE <S>
	TUBE SIZE,		COATED TUBE
	NOMINAL		O.D. MAX.
	4.76	mm	5.23	mm
	6.00	mm	6.52	mm
	6.35	mm	6.87	mm
	7.94	mm	8.46	mm
	8.00	mm	8.52	mm
	9.53	mm	10.05	mm
	10.00	mm	10.52	mm
	11.11	mm	11.65	mm
	12.70	mm	13.24	mm
	14.29	mm	14.83	mm
	15.88	mm	16.42	mm
4.2 Fluoride Coating over Zinc or Zinc Aluminum Alloy
A. Color shall be black or olive drab unless otherwise specified
on the engineering drawing.
B. The thickness of the electroplated zinc is 0.001 Inch
(25 microns) minimum for MS-1806 0.0005 inch (13 microns) for
MS-3235.
The minimum coating coverage is 180 g/m2 and
90 g/m2 for MS-1806 and MS-3235 respectively. For the Zinc
5% Aluminum Alloy coating, the maximum average thickness is 0.0002
inch (5.2 microns); the maximum coating coverage is
36 g/m2 per ASTM A 90. <S>
C. The thickness of the fluoride coating is 0.0004 Inch (10 microns)
minimum per ASTM B487.
4.3 Aluminum Rich Organic Coating Over Zinc-Aluminum Alloy.
A. Color shall be silver-grey unless otherwise specified.
B. Thickness and coating coverage of zinc-alloy coating paragraph
4.2.B.
C. The minimum coating coverage of the aluminum rich organic coating
is 8 g/m2 (0.026 oz/ft.2) per ASTM A 90.
4.4 Duplex - Organic Coating Containing Zinc And Chromate Particles
Applied to a Lead-Tin Alloy Coating.
A. Color - The color shall be grey or green unless otherwise specified.
B. The maximum coating coverage is 31 g.m2 (0.10 oz/ft2) for
the lead-tin coating applied to MS-1806 double wail brazed tubing. The
minimum coating coverage is 18 g/m2 (0.06 oz/ft2) for
lead tin coating applied to MS-3235 electric resistance welded tubing per
ASTM A 309, LP-461H-102.
C. The composition of the lead-tin alloy shall consist of 12% maximum
tin and balance lead for coating applied over MS-1806 double
wall brazed tubing and 7% minimum tin and balance lead for coating over
MS-3235 single wall tubing.
D. The minimum coating coverage of the organic zinc chromate coating is
15 g/m2 (0.05 oz/ft.2) per ASTM A 90.
E. The coating shall be free of bare spots visible to the unaided eye.
4.5 Lead-Tin Coated Only Parts
Lead Tin requirements to paragraph 4.4.B except the minimum coating
coverage is 49 g/m2 (0.16 oz/ft2) for the lead tin coating
applied to (MS-1806) double brazed tubing. The minimum
coating coverage is 18 g/m2 (0.06 oz/ft2) for lead tin
coating applied to MS-3235 electric resistance welded tubing per
ASTM A 309, LP-461H-102.
4.6 Workmanship
The final coating shall be smooth, even, and free from cracks, blisters,
pinholes, nodules and other harmful defects. Coverage shall be
uniform in appearance and complete.
4.7 Adhesion and Ducrlity
The zinc or zinc alloy or lead-tin alloy shall have good adhesion to the
substrate and to itself, and show no tendency toward flaking or
peeling when tested in accordance with ASTM Standard Test Method
B 571.
Make a cross cut pattern on the coating to the tubing then take test
over the cross cut. Check for any separation of the nylon or fluoride
or aluminum rich organic or zinc rich organic coating.
4.8 Ferroxyl Test
The tin-lead alloy coated tubing shall be free from uncoated spots.
Any uncoated areas which are visible to the unaided eye at normal
reading distance shall be considered unsatisfactory and sufficient
cause for rejection. The presence of uncoated areas may be verified
by the Ferroxyl Test, Chrysler Laboratory Procedure 461 H-80.
5.0 CORROSION RESISTANCE***
5.1 Nylon 12 over Hot Dipped Zinc Aluminum Alloy
A. Tubing shall show no lifting or delamination of coating; red rust
is allowed only at knife cut after 2000 hours per ASTM B-117.
B. The OD tube coating shall show no lifting or delamination when
cut and peel tested after fluid soaks in Table 5, shown below, for
500 hours. After soak testing, cut and peel test by scrubing
two longitudinal knife cuts at 0.093 inch (2.3 mm) separation and
cutting at 90 degrees to effect a tab start section of Nylon 12
coating. After testing in fluid soaks per Table 5, Nylon 12 may
lift when pulled for less than 6.35 mm (0.25 inches) and then
tear. No adhesive failure to base metal is permissible.
Cohesive failure thru primer is acceptable. Evaluation of ID
corrosion for coding such as Nickel plating at 3.8 microns
(0.00015 Inch) minimum thickness after soak per Table 5 for 500
hours shall show no red rust or pitting after 500 hours exposure
in soak fuels referenced in Table 5.

[0068]

TABLE 5
SOAK FLUID FOR TESTING NYLON 12 ADHESION
OR ID CORROSION
1.  California Phase 2 Reformulated Gasoline per MS-9368
2.  500 ppm (0.05%) Sulfur as DTBS - Ditertiary Butyl
    DiSulphide added to MS-9368
3.  Distilled Water
4.  RFG - Butyl peroxide and lauroyl peroxide (2.6 ml Butyl hydro
    peroxide per liter of RFG per MS-9368 or 10.4 ml Lauroyl
    peroxide per liter of RFG per MS-9368)
5.  UL gas per MS-8004 Certification Grade + 22%
    aggressive ethanol (Refer to Notes 1 and 2).
6.  UL gas per MS-8004 Certification Grade + 85%
    aggressive ethanol (Refer to Notes 1 and 2).
7.  UL gas per MS-8004 Certification Grade + 50%
    aggressive ethanol (Refer to Notes 1 and 2).
8.  MS-4957 Calibration Fluid
9.  Leaded gasoline - indolence 30 or MS-8004 with 3 grams per
    gallon lead
10. Fuel C (50% so octane, 50% toluene)
11. TF2 (Dupont Waiver Fuel) (Refer to Note 3)
12. MS-9448 high cetane diesel fuel with 0.2% sulfur by weight
13. MS-9448 high cetane diesel fuel-highly paraffinic, >90%
    paraffin, >55CN
14. MS-9448 high cetane diesel fuel-highly aromatic-made with
    highly aromatic cycle oil>50% aromatic, >55CN, 0.15%
    organic cetane improver
15. MS-high cetane diesel fuel-highly aromatic-as above with 2% by
    volume aggressive water.
16. Biodiesel 100% (Rape Seed)
17. Biodiesel (Rape Seed) with 5% by volume MS-9448 high cecane
    diesel fuel
18. Biodiesel (Rape Seed) with 20% by volume MS-9448 high cetane
    diesel fuel
Note 1: AGGRESSIVE ETHANOL - 995 ml fuel grade ethanol (98% ADM Archer Daniels Midland), add 5 ml aggressive water (equivalent to 1000 ml aggressive ethanol).
Note 2: AGGRESSIVE WATER - 1 liter distilled water, ad 1 gram NaCl, add 0.9 gram NaSO add 28 ml H COOH concentrated acetic acid
Note 3: DUPONT WAIVER FUEL TP2 - 15% volume olefinic 45-50%, add volume aromatic, add 5% volume methanol, add 2.5% volume ethanol

[0069]

TABLE 7
MATERIALS TESTED AND FOUND ACCEPTABLE
TO THIS STANDARD
Nickel 3.3 mm minimum undiffused (unalloyed) and nickel 5.0 mm
minimum diffused (alloyed)
Copper coated ID developed from double wall copper brazed steel tubing
Nickel 3.8 mm minimum undiffused (unalloyed) and nickel 5.0 mm
minimum diffused (alloyed) Copper coated id developed from a double
wall copper brazed steel tubing
C.  Gravelometer test per SAE J400 (LP-163PB-39-01)
Five (5) pints at with −18 Degrees C. (0 Degrees F.) and salt spray per
ASTM B-117 shall be tested for 1500 hours. Red rust is allowed at gravel
impacted areas; 5% of impacted areas, maximum.
D.  Gravelometer Salt Exposure Test
1.  Test tubes per Gravelometer test - SAE J400 (LP-163PB-39-01)
    five (5) pints at 482 kPa (70 psi) and tubes oriented at
    45 degrees from the nozzle.
2.  Expose tubes to 48 hours salt spray ASTM B-117.
3.  Within 2 hours following removal from salt spray, expose the tube
    to five (5) additional pints with gravel per SAE J400
    (LP-163PB-39-01) as 482 kPa (70 psi) and tubes oriented at
    45 degrees from nozzle, allow the tube to condition for
    24 hours at room temperature.
4.  Expose the tube to 1, 2 and 3 one additional time.
5.  Expose tubes for 400 hours.
6.  Test Nylon after exposure by pulling. Nylon may lift when pulled
    for less than 6.35 mm (.25 inches) and then tear.
7.  After exposure, no lifting or delamination of coating is allowed.
    Red rust is allowed only at gravel impacted areas: 10% of the
    impacted areas, maximum.
E.  Chrysler Proving Ground Vehicle Corrosion Test per LP-161H-117
    for 170 cycles or the test equivalent of 10 years of operation.
    Burst strength of brake lines shall he greater than or equal to
    13,789 KPa (2000 psi). Fuel lines, power steering, and
    transmisson on cooler lines shall be functional after the test.
5.2 Fluoride (Poly vinylidene fluoride or polyvinyl fluoride) over
    Zinc or Zinc Aluminum Alloy or Aluminum Rich over Zinc
    Aluminum Alloy, or Zinc Aluminum alloy.
A.  Fluoride over Zinc or Zinc Aluminum Alloy or Aluminum Rich
    over Zinc Aluminum Alloy (A, B), Salt Spray corrision
    resistance per ASTM 224 B-117 shall meet 400 hours resistance to
    red rust at knife cut cross scribed or circumferentially scribed
    to tubing surface.
B.  Fluoride over Zinc or Zinc Aluminum Alloy or Aluminum Rich
    over Zinc Aluminum Alloy (A, B), Gravelometer test per
    SAE J400 1 pint at - 18 Degrees C. (0 Degrees F.) and salt
    spray per ASTM B-117 shall meet 1000 hours with no red rust
    at gravel impacted surfaces.
C.  For zinc aluminum alloy, salt spray corrosion resistance for
    360 hours salt spray per ASTM B-117 no more than 1% red rust
    over any 25.4 mm (1 inch) length compared to ASTM D 610,
    Plate 6.
5.3 Organic Coating Containing Chromate And Zinc particles Over
    Lead Tin Alloy
A.  The final assembly or part shall be capable of withstanding 200
    hours resistance to red rust and shall show no more than one
    base metal corrosion spot, 1.5 mm (0.060 in.) In diameter or
    larger in any area 500 mm3 (0.77 square inches) when
    Salt Spray tested per ASTM B-117.
5.4 Nickel Electroplated coating at inside diameter of Tubing
Nickel placing 3.8 microns (0.00015 inch) minimum thickness shall show
no red rust after 500 hours exposure in soak fuels referenced in
Section 5.1.B.
6.0 CONTROL
While samples may be taken from incoming shipments and checked to the
requirements of this specification, the supplier shall accept the
responsibility for meeting the stated requirements without dependence
on the purchaser's inspection.
Production lots shall be equivalent in every respect to samples initially
approved, and any change in Materials or Processing or Processing prac-
tices require resubmission of sample parts.
7.0 GENERAL INFORMATION
Three asterisks *** after the paragraph header denotes multiple technical
changes to the paragraph. A triple asterisk before and after a string of
test (***text***) identifies a single change.
Certain important information relative to this standard has been included
in separate standards. To assure the processes submitted meet all of the
Chrysler requirements, it is mandatory that the requirements in the follow-
ing standards be met.
CS-9800 - Application of this standard, the subscription service, and
approved sources
CS-9801 - General quality requirements
CS-9003 - Regulated substances and recyclability
Within Engineering Standards, the designations <S>, <E>, <N>,
<T>, or <H> will be substituted for the Safety, Emission, Noise, Theft
Prevention, or Homologanon Shields respectively. The designations <D>
and <P> will be substituted for the Diamond and Pentagon symbols
respectively.
This standard has safety, noise, emissions or theft prevention significance
only when appropriate drawings depict the coatings with a safety shield. It
is necessary to review the part drawing to ascertain which parts of a
standard have safety, noise emission or theft prevention significance.
Paragraph numbers in this standard shall not be changed without first
reviewing the paragraph reference on all affected drawings.
Processes shall only be purchased from those sources listed under
Engineering Approved Source List.

[0070]

TABLE F
Test Results
Specimen
Number
Section 5 1A - Scribed then 2000 Hours Salt Fog
	Results Alter Salt Fog
1	No lifting or delamination between the primer and the ZnAl
	substrate
2	No lifting or delamination between the primer and the ZnAl
	substrate
3	No lifting or delamination between the primer and the ZnAl
	substrate
4	No lifting or delamination between the primer and the ZnAl
	substrate
5	No lifting or delamination between the primer and the ZnAl
	substrate
6	No lifting or delamination between the primer and the ZnAl
	substrate
Require-	No lifting or delamination between the primer and the ZnAl
ment	substrate
Section 5 1B - Scribed, then 500 Hours Fuel Soak
#1) California Phase 2 Reformulated Gasoline
	Results After Fuel Soak
1	No lifting or delamination between the primer and the ZnAl
	substrate
2	No lifting or delamination between the primer and the ZnAl
	substrate
3	No lifting or delamination between the primer and the ZnAl
	substrate
4	No lifting or delamination between the primer and the ZnAl
	substrate
5	No lifting or delamination between the primer and the ZnAl
	substrate
6	No lifting or delamination between the primer and the ZnAl
	substrate
Require-	No lifting or delamination between the primer and the ZnAl
ment	substrate
#2) California Phase 2 Reformulated Gasoline - 0.05% Diteruary
Butyl DiSulphide
	Results After Fuel Soak
1	No lifting or delamination between the primer and the ZnAl
	substrate
2	No lifting or delamination between the primer and the ZnAl
	substrate
3	No lifting or delamination between the primer and the ZnAl
	substrate
4	No lifting or delamination between the primer and the ZnAl
	substrate
5	No lifting or delamination between the primer and the ZnAl
	substrate
6	No lifting or delamination between the primer and the ZnAl
	substrate
Require-	No lifting or delamination between the primer and the ZnAl
ment	substrate
#3) Distilled Water
	Results After Fuel Soak
1	No lifting or delamination between the primer and the ZnAl
	substrate
2	No lifting or delamination between the primer and the ZnAl
	substrate
3	No lifting or delamination between the primer and the ZnAl
	substrate
4	No lifting or delamination between the primer and the ZnAl
	substrate
5	No lifting or delamination between the primer and the ZnAl
	substrate
6	No lifting or delamination between the primer and the ZnAl
	substrate
Require-	No lifting or delamination between the primer and the ZnAl
ment	substrate
#4) California Phase 2 Reformulated Gasoline - 0.26% Butyl
Hydro Peroxide
	Results After Fuel Soak
1	No lifting or delamination between the primer and the ZnAl
	substrate
2	No lifting or delamination between the primer and the ZnAl
	substrate
3	No lifting or delamination between the primer and the ZnAl
	substrate
4	No lifting or delamination between the primer and the ZnAl
	substrate
5	No lifting or delamination between the primer and the ZnAl
	substrate
6	No lifting or delamination between the primer and the ZnAl
	substrate
Require-	No lifting or delamination between the primer and the ZnAl
ment	substrate
#5) Unleaded Gas - 22% Aggressive Ethanol
	Results After Fuel Soak
1	No lifting or delamination between the primer and the ZnAl
	substrate
2	No lifting or delamination between the primer and the ZnAl
	substrate
3	No lifting or delamination between the primer and the ZnAl
	substrate
4	No lifting or delamination between the primer and the ZnAl
	substrate
5	No lifting or delamination between the primer and the ZnAl
	substrate
6	No lifting or delamination between the primer and the ZnAl
	substrate
Require-	No lifting or delamination between the primer and the ZnAl
ment	substrate
#6) Unleaded Gas - 85% Aggressive Ethanol
	Results After Fuel Soak
1	No lifting or delamination between the primer and the ZnAl
	substrate
2	No lifting or delamination between the primer and the ZnAl
	substrate
3	No lifting or delamination between the primer and the ZnAl
	substrate
4	No lifting or delamination between the primer and the ZnAl
	substrate
5	No lifting or delamination between the primer and the ZnAl
	substrate
6	No lifting or delamination between the primer and the ZnAl
	substrate
Require-	No lifting or delamination between the primer and the ZnAl
ment	substrate
#7) Unleaded Gas - 10% Ethanol
	Results After Fuel Soak
1	No lifting or delamination between the primer and the ZnAl
	substrate
2	No lifting or delamination between the primer and the ZnAl
	substrate
3	No lifting or delamination between the primer and the ZnAl
	substrate
4	No lifting or delamination between the primer and the ZnAl
	substrate
5	No lifting or delamination between the primer and the ZnAl
	substrate
6	No lifting or delamination between the primer and the ZnAl
	substrate
Require-	No lifting or delamination between the primer and the ZnAl
ment	substrate
#8) 100% Shipping Fluid
	Results After Fuel Soak
1	No lifting or delamination between the primer and the ZnAl
	substrate
2	No lifting or delamination between the primer and the ZnAl
	substrate
3	No lifting or delamination between the primer and the ZnAl
	substrate
4	No lifting or delamination between the primer and the ZnAl
	substrate
5	No lifting or delamination between the primer and the ZnAl
	substrate
6	No lifting or delamination between the primer and the ZnAl
	substrate
Require-	No lifting or delamination between the primer and the ZnAl
ment	substrate
#9) Leaded Gasoline - Indolene 30
	Results After Fuel Soak
1	No lifting or delamination between the primer and the ZnAl
	substrate
2	No lifting or delamination between the primer and the ZnAl
	substrate
3	No lifting or delamination between the primer and the ZnAl
	substrate
4	No lifting or delamination between the primer and the ZnAl
	substrate
5	No lifting or delamination between the primer and the ZnAl
	substrate
6	No lifting or delamination between the primer and the ZnAl
	substrate
Require-	No lifting or delamination between the primer and the ZnAl
ment	substrate
#10) Fuel C
	Results After Fuel Soak
1	No lifting or delamination between the primer and the ZnAl
	substrate
2	No lifting or delamination between the primer and the ZnAl
	substrate
3	No lifting or delamination between the primer and the ZnAl
	substrate
4	No lifting or delamination between the primer and the ZnAl
	substrate
5	No lifting or delamination between the primer and the ZnAl
	substrate
6	No lifting or delamination between the primer and the ZnAl
	substrate
Require-	No lifting or delamination between the primer and the ZnAl
ment	substrate
#11) TFZ (Dupont Waiver Fuel)
	Results After Fuel Soak
1	No lifting or delamination between the primer and the ZnAl
	substrate
2	No lifting or delamination between the primer and the ZnAl
	substrate
3	No lifting or delamination between the primer and the ZnAl
	substrate
4	No lifting or delamination between the primer and the ZnAl
	substrate
5	No lifting or delamination between the primer and the ZnAl
	substrate
6	No lifting or delamination between the primer and the ZnAl
	substrate
Require-	No lifting or delamination between the primer and the ZnAl
ment	substrate
Section 5.1C - Gravelometer at −18° C. then 1500 Hours Salt Fog
	Results After Salt Fog
1	0% red rust at impacted areas
2	0% red rust at impacted ateas
3	0% red rust at impacted areas
4	0% red rust at impacted areas
5	0% red rust at impacted areas
6	0% red rust at impacted areas
Require-	<5% red rust at impacted areas
ment
Section 5.1D - Intermittent Room Temperture Gravelometer and Salt Fog
	Peel Test Results	Visual Results
	After Final Salt Fog	After Final Salt Fog
1	No lifting or delamination	0% red rust at impacted areas
2	No lifting or delamination	0% red rust at impacted areas
3	No lifting or delamination	0% red rust at impacted areas
4	No lifting or delamination	0% red rust at impacted areas
5	No lifting or delamination	0% red ruse at impacted areas
6	No lifting or delamination	0% red rust at impacted areas
Require-	No lifting or delamination	<10% red rust at impacted areas
ment

[0071]

TABLE G
Test Results:
3/15″ North American Nvclad GP coated steel tubing
Specimen
Number
#1) California Phase 2 Reformulated Gasoline
         Results After 500 Hours Fuel Soak
1        No lifting or delamination between the primer and the ZnAl
         substrate or the PA12 coating
2        No lifting or delamination between the primer and the ZnAl
         substrate or the PA12 coating
3        No lifting or delamination between the primer and the ZnAl
         substrate or the PA12 coating
4        No lifting or delamination between the primer and the ZnAl
         substrate or the PA12 coating
5        No lifting or delamination between the primer and the ZnAl
         substrate or the PA12 coating
6        No lifting or delamination between the primer and the ZnAl
         substrate or the PA12 coating
Require- No lifting or delamination between the primer and the ZnAl
ment     substrate or the PA12 coating
2) California Phase 2 Reformulated Gasoline - 0.05% Diteruary
Butyl DiSulphide
         Results After 500 Hours Fuel Soak
1        No lifting or delamination between the primer and the ZnAl
         substrate or the PA12 coating
2        No lifting or delamination between the primer and the ZnAl
         substrate or the PA12 coating
3        No lifting or delamination between the primer and the ZnAl
         substrate or the PA12 coating
4        No lifting or delamination between the primer and the ZnAl
         substrate or the PA12 coating
5        No lifting or delamination between the primer and the ZnAl
         substrate or the PA12 coating
6        No lifting or delamination between the primer and the ZnAl
         substrate or the PA12 coating
Require- No lifting or delamination between the primer and the ZnAl
ment     substrate or the PA12 coating
#3) Distilled Water
         Results After 500 Hours Fuel Soak
1        No lifting or delamination between the primer and the ZnAl
         substrate or the PA12 coating
2        No lifting or delamination between the primer and the ZnAl
         substrate or the PA12 coating
3        No lifting or delamination between the primer and the ZnAl
         substrate or the PA12 coating
4        No lifting or delamination between the primer and the ZnAl
         substrate or the PA12 coating
5        No lifting or delamination between the primer and the ZnAl
         substrate or the PA12 coating
6        No lifting or delamination between the primer and the ZnAl
         substrate or the PA12 coating
Require- No lifting or delamination between the primer and the ZnAl
ment     substrate or the PA12 coating
#4) California Phase 2 Reformulated Gasoline - 0.26% Butyl
Hydro Peroxide
         Results After 500 Hours Fuel Soak
1        No lifting or delamination between the primer and the ZnAl
         substrate or the PA12 coating
2        No lifting or delamination between the primer and the ZnAl
         substrate or the PA12 coating
3        No lifting or delamination between the primer and the ZnAl
         substrate or the PA12 coating
4        No lifting or delamination between the primer and the ZnAl
         substrate or the PA12 coating
5        No lifting or delamination between the primer and the ZnAl
         substrate or the PA12 coating
6        No lifting or delamination between the primer and the ZnAl
         substrate or the PA12 coating
Require- No lifting or delamination between the primer and the ZnAl
ment     substrate or the PA12 coating
#5) Unleaded Gas - 22% Aggressive Ethanol
         Results After 500 Hours Fuel Soak
1        No lifting or delamination between the primer and the ZnAl
         substrate or the PA12 coating
2        No lifting or delamination between the primer and the ZnAl
         substrate or the PA12 coating
3        No lifting or delamination between the primer and the ZnAl
         substrate or the PA12 coating
4        No lifting or delamination between the primer and the ZnAl
         substrate or the PA12 coating
5        No lifting or delamination between the primer and the ZnAl
         substrate or the PA12 coating
6        No lifting or delamination between the primer and the ZnAl
         substrate or the PA12 coating
Require- No lifting or delamination between the primer and the ZnAl
ment     substrate or the PA12 coating
#6) Unleaded Gas - 85% Aggressive Ethanol
         Results After 500 Hours Fuel Soak
1        No lifting or delamination between the primer and the ZnAl
         substrate or the PA12 coating
2        No lifting or delamination between the primer and the ZnAl
         substrate or the PA12 coating
3        No lifting or delamination between the primer and the ZnAl
         substrate or the PA12 coating
4        No lifting or delamination between the primer and the ZnAl
         substrate or the PA12 coating
5        No lifting or delamination between the primer and the ZnAl
         substrate or the PA12 coating
6        No lifting or delamination between the primer and the ZnAl
         substrate or the PA12 coating
Require- No lifting or delamination between the primer and the ZnAl
ment     substrate or the PA12 coating
#7) Unleaded Gas - 10% Ethanol
         Results After 500 Hours Fuel Soak
1        No lifting or delamination between the primer and the ZnAl
         substrate or the PA12 coating
2        No lifting or delamination between the primer and the ZnAl
         substrate or the PA12 coating
3        No lifting or delamination between the primer and the ZnAl
         substrate or the PA12 coating
4        No lifting or delamination between the primer and the ZnAl
         substrate or the PA12 coating
5        No lifting or delamination between the primer and the ZnAl
         substrate or the PA12 coating
6        No lifting or delamination between the primer and the ZnAl
         substrate or the PA12 coating
Require- No lifting or delamination between the primer and the ZnAl
ment     substrate or the PA12 coating
#8) 100% Shipping Fluid
         Results After 500 Hours Fuel Soak
1        No lifting or delamination between the primer and the ZnAl
         substrate or the PA12 coating
2        No lifting or delamination between the primer and the ZnAl
         substrate or the PA12 coating
3        No lifting or delamination between the primer and the ZnAl
         substrate or the PA12 coating
4        No lifting or delamination between the primer and the ZnAl
         substrate or the PA12 coating
5        No lifting or delamination between the primer and the ZnAl
         substrate or the PA12 coating
6        No lifting or delamination between the primer and the ZnAl
         substrate or the PA12 coating
Require- No lifting or delamination between the primer and the ZnAl
ment     substrate or the PA12 coating
#9) Leaded Gasoline - Indolene 30
         Results After 500 Hours Fuel Soak
1        No lifting or delamination between the primer and the ZnAl
         substrate or the PA12 coating
2        No lifting or delamination between the primer and the ZnAl
         substrate or the PA12 coating
3        No lifting or delamination between the primer and the ZnAl
         substrate or the PA12 coating
4        No lifting or delamination between the primer and the ZnAl
         substrate or the PA12 coating
5        No lifting or delamination between the primer and the ZnAl
         substrate or the PA12 coating
6        No lifting or delamination between the primer and the ZnAl
         substrate or the PA12 coating
Require- No lifting or delamination between the primer and the ZnAl
ment     substrate or the PA12 coating
#10) Fuel C
         Results After 500 Hours Fuel Soak
1        No lifting or delamination between the primer and the ZnAl
         substrate or the PA12 coating
2        No lifting or delamination between the primer and the ZnAl
         substrate or the PA12 coating
3        No lifting or delamination between the primer and the ZnAl
         substrate or the PA12 coating
4        No lifting or delamination between the primer and the ZnAl
         substrate or the PA12 coating
5        No lifting or delamination between the primer and the ZnAl
         substrate or the PA12 coating
6        No lifting or delamination between the primer and the ZnAl
         substrate or the PA12 coating
Require- No lifting or delamination between the primer and the ZnAl
ment     substrate or the PA12 coating
#11) TFZ (Dupone Waiver Fuel)
         Results After 500 Hours Fuel Soak
1        No lifting or delamination between the primer and the ZnAl
         substrate or the PA12 coating
2        No lifting or delamination between the primer and the ZnAl
         substrate or the PA12 coating
3        No lifting or delamination between the primer and the ZnAl
         substrate or the PA12 coating
4        No lifting or delamination between the primer and the ZnAl
         substrate or the PA12 coating
5        No lifting or delamination between the primer and the ZnAl
         substrate or the PA12 coating
6        No lifting or delamination between the primer and the ZnAl
         substrate or the PA12 coating
Require- No lifting or delamination between the primer and the ZnAl
ment     substrate or the PA12 coating

[0072] While the invention has been described in connection with what is presently considered to be the most practical and preferred embodiments, it is to be understood that the invention is not to be limited to the disclosed embodiments but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims, which scope is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures as is permitted under the law.

Claims

1. A multi-layer tube, comprising: a metal tube having an outer surface; a zinc layer bonded to the metal tube outer surface, wherein the zinc layer is selected from the group consisting of zinc plating, zinc nickel alloys, zinc cobalt alloys, zinc aluminum alloys, and mixtures thereof; a surface treatment layer bonded to the zinc layer, wherein the surface treatment layer is selected from the group consisting of a zinc/aluminum/rare earth alloy, phosphate, chromate, and mixtures thereof; a priming layer; a first polymeric layer bonded to the priming layer, wherein the first polymeric layer is selected from the group consisting of thermoplastic elastomers, ionomers, nylons, fluoropolymers, and mixtures thereof; and a second polymeric layer bonded to the first polymeric layer, wherein the second polymeric layer is selected from the group consisting of nylons, thermoplastic elastomers, fluoropolymers, and mixtures thereof.

2. The multi-layer tube as defined in claim 1, further comprising a third polymeric layer interposed between, and bonded to the first and second polymeric layers, wherein the third polymeric layer is selected from the group consisting of ionomers, nylons, ethylene vinyl alcohol, polyolefins, and mixtures thereof.

3. The multi-layer tube as defined in claim 1, wherein the zinc layer has a thickness ranging between about 10 to 25 microns.

4. The multi-layer tube as defined in claim 1, wherein the surface treatment layer has a weight ranging between about 37.3 g/m2 and about 97.7 g/m2.

5. The multi-layer tube as defined in claim 1 wherein the first and second polymeric layers, combined, have a thickness ranging between about 75 to 300 microns.

6. The multi-layer tube as defined in claim 5 wherein the first and second layer thickness ranges between about 125 to 250 microns.

7. The multi-layer tube as defined in claim 2 wherein the first, second and third polymeric layers, combined, have a thickness ranging between about 75 to 300 microns.

8. The multi-layer tube as defined in claim 7 wherein the first, second and third layer thickness ranges between about 125 to 250 microns.

9. The multi-layer tube as defined in claim 1 wherein the zinc/aluminum/rare earth alloy of the surface treatment layer consists essentially of: between about 85% and about 97% Zn; between about 4% and about 15% Al; and at least about 5 ppm of a rare earth-containing alloy.

10. The multi-layer tube as defined in claim 1 wherein the first polymeric layer consists essentially of an ionomer and a nylon.

11. The multi-layer tube as defined in claim 10 wherein the ionomer is ethylene methacrylic acid copolymer—partial metal salt, and wherein the nylon is Nylon 12.

12. The multi-layer tube as defined in claim 11 wherein the ethylene methacrylic acid copolymer—partial metal salt comprises between about 10% and about 70% of the first polymeric layer, and wherein the Nylon 12 comprises between about 90% and about 30% of the first polymeric layer.

13. The multi-layer tube as defined in claim 11 wherein the second polymeric layer consists essentially of a nylon.

14. The multi-layer tube as defined in claim 13 wherein the second polymeric layer consists essentially of Nylon 12.

15. A process for manufacturing a multi-layer tubing for conveying fluids comprising the step of: extruding multiple layers of a melt-processible thermoplastic to a pretreated metal tube having an external surface with at least a zinc based coating, a sealant coating on top of the zinc based coating, and a primer coating on top of the sealant coating.

16. The process of claim 15 wherein the melt-processible thermoplastic is selected from the group consisting of Nylon 12, Nylon 6, zinc chloride resistant Nylon 6, thermoplastic elastomers, fluoropolymers, and mixtures thereof.

17. The process as defined in claim 16 wherein the primer coating is applied by an airless spray system in a closed atmosphere, wherein substantially no volatile organic compounds escape into the atmosphere.

18. A process for manufacturing a multi-layer tubing for conveying fluids in a vehicle system comprising the steps of: coating a metal tube with a zinc based coating selected from a group consisting of zinc, zinc-nickel alloy, zinc-cobalt alloy, zinc-aluminum alloy, and mixtures thereof; sealing the zinc based coating on the metal tube with at least one sealant coating selected from the group consisting of a phosphate surface treatment, a chromate surface treatment, a zinc-aluminum alloy surface treatment, and combinations thereof; applying a primer after the sealing step; coextruding at least one melt-processible thermoplastic layer onto the pretreated metal tube with the at least one layer overlying the pretreated metal tube, wherein the first layer is selected from the group consisting of Nylon 12, Nylon 6, zinc chloride resistant Nylon 6, thermoplastic elastomers, fluoropolymers, ionomers, and mixtures thereof; and applying vacuum pressure between the pretreated metal tube and the melt-processible thermoplastic during the extruding step to draw the thermoplastic into intimate contact with the pretreated metal tube.

19. The multi-layer tube of claim 1 wherein the priming layer is a nylon primer having as a major constituent titanium dioxide.

20. The multi-layer tube of claim 1 wherein both the first and second polymeric layers comprise a low viscosity, low molecular weight Nylon 12 material.