MXPA01004977A - Bonding of steel strips in steel strip laminate pipe - Google Patents

Abstract

A steel strip laminate pipe having increased lap shear strength and peel off strength between the steel layers in the pipe and a method for making such a steel strip pipe are provided. Steel strips coated with a sol-gel or a silane adhesion promoter are wound over an inner lining to form steel layers bonded to each other in a steel strip laminate pipe. In an alternate embodiment, fiber fillers and resin are used to bond the steel layers in the pipe together. In further embodiment, glass sphere and resin are used to bond the steel layers together. The steel strips bonded together using continuous reinforced fiber filler or glass spheres may be coated with sol-gel or silane. In an alternate embodiment, the sol-gel or silane may also be mixed in the resin used to bond the steel layers together.

Description

UNION OF STEEL STRIPS IN PIPE LAMINATED WITH THE SAME BACKGROUND OF THE INVENTION High-pressure conduits, such as oil and gas pipes, have been constructed, generally with conventional steel pipes. These pipes are subject to both internal and external pressures. Internal pressure is required to transport the fluid or gases inside the pipes. The external pressure is created by the weight of the soil or water on the pipe when the pipe is embedded in the ground or when it is submerged in the water. As steel pipes provide the resistance requirement to withstand internal and external pressures, the pipes have a high susceptibility to corrosion. A corrosive environment is favored by contact between internal foreign media (for example, liquids or gases that are transported through the pipe) and steel, or by contact with external conductive foreign media and steel. Foreign extraneous media could be earth in cases where the pipe is buried under the ground, or seawater in cases where the pipe is submerged in an ocean, or water in cases Ref: 129824 where the pipe runs along sewer networks or is exposed to rain. Corrosion decreases the resistance of the pipe and can cause the pipeline to leak or explode under pressure. To overcome this disadvantage, reinforced steel composite pipes have been developed. These pipes have a steel wall coated with a polymeric material, or have a steel wall embedded in the fiber reinforced composite, such as a fiberglass resin system. The coating or resin system protects the steel from corrosion by protecting it from any contact with foreign media. An example of reinforced steel composite pipe is described in Cocks Patent No. 4,351,364, the subject of which is incorporated herein by reference. The pipe described in that document is a section of structural wall placed between two layers of internal and external coatings. The coatings are rich layers of resin reinforced with fiberglass or with other fibers. The structural wall section is made of three or more layers of structural steel reinforcement, which are coated with structural epoxy resin. The individual layers of the pipe are mounted, successively, one on top of the other, on a mandrel or machined winding pipe. Each coating layer is formed by the helically wound resin, which is moistened with glass fiber strands. Each steel layer is formed by the helical winding of a steel strip coated with resin. The steel layers are rolled one over the top of the other. Once "rolled" the pipe is cured. This type of pipeline is commonly referred to as laminated pipe with steel strips or "SSL pipeline". Typically, the desired blade cut resistance between the overlapping steel layers in the SSL pipe is 1800 psi. Such resistance can not be achieved by adhering one layer of steel to the other using only a resin system. In order to achieve such strength, it is common to sandblast the steel before winding it to form the steel layers in the pipe. Sandblasting creates a mechanical roughness on the steel providing a stronger mechanical / adhesive bond. However, this joint does not have a long-term durability under humid environments. The test sample of the blade's cut resistance consists of sanding sandblasting steel samples, which are bonded using the EPON 826 / IPD adhesive which shows an 80% loss of blade cut resistance after of 505 hours of exposure to hot water. In addition, the aging of the surface of sandblasted steel reduces, significantly, the resistance to the cutting of the leaf due to the oxidation of the surface. In addition, sanding with sandblasting is a burdensome process. Typically, an air compressor of 5000 C.V. of power will be required to sandblast serial productions of steel strips. Special equipment would also be necessary due to the nature with excessive dust and noise from sandblasting. As such, a system is needed to join the layers formed with steel strips to one another and so that the SSL pipe linings could avoid the need to sandblast the steel strips. It has also been discovered that steel strip layers, bonded together with only one resin, have inadequate peel strength. The inadequate peel strength is believed to be caused by a variation in the joint thickness along the length of the steel strip forming the layer. The resin bond thickness control is not typically very accurate at production speeds.

Sometimes flake fillings or pieces of glass are used in the resin to improve the shear strength between the steel strips. Typically, glass chip fillings constitute approximately 5 to 10% by weight of the resin. However, even with the use of glass chip fillers it is difficult to control the joint thickness between the strips at production speeds, in this way, inadequate resistance to stripping of the strip results. Another problem with the joining of a steel strip to another one in the SSL pipes is the cracking of the resin matrix between the steel strips that also results in a reduction of the peel strength. A further problem is the resin shrinkage that occurs during curing and which also results in a decrease in the bond strength between the steel strips. SSL pipes are typically subjected to heat and moisture conditions and the bond between the steel strips often fails under a combined failure mode, that is, a failure to cut / peel resistance. In itself, it is important that the joints between the steel layers maintain a significant percentage of their strength a-1 blade cut and the peel strength under heat and humidity conditions. In addition, in order to accelerate the manufacturing process of the SSL pipeline, it is desirable that the caking time (ie, the time it takes to remove the excess resin between the steel strips forming the layers that are going away to join) of any resin system used is relatively short to reduce manufacturing times and therefore, reduce manufacturing costs. In this way, a resin system is needed which allows to control the joint thickness between the layers of adjacent steel strips and between the layers of steel strips and the coatings of the SSL pipeline at production speeds. In addition, a resin system with increased resistance to crack growth when cured and subject to reduced shrinkage during cure is needed. In addition, a resin system that provides improved release and shear strengths between the steel strips of the SSL pipe under heat and humidity conditions that allows for reduced caking times is desirable.

SUMMARY OF THE INVENTION To improve the shear strength of the sheet between the steel layers in the SSL pipe an adhesion stimulator in the form of a sol-gel or an organofunctional silane is used to coat the steel strips forming the steel layers. In one embodiment, a sol-gel coating is used as the adhesion stimulator. Sol is a solution that contains partially reactive metallo-organic precursors (often a metal alkoxide such as -OSi (OR) 3) in a solvent, usually alcohol. R is a non-hydrolyzable organic radical having a functionality that allows the sol-gel coating to bond with the epoxy resin or other organic resins. Gel is a substance that contains a continuous solid structure that encloses a continuous liquid phase formed by means of the reaction in the sun. Sol-gel processing involves the preparation of a solid, usually a film or coating that comes from sol and gel. Typically, sol-gel is formed by hydrolyzing and condensing the sol solution. The chromate-modified sol-gel coating provides better long-term durability in an environment of heat and humidity.

In another embodiment, the steel strips are coated with an organofunctional or bifunctional silane. The organofunctional silane, such as silane Y-R-Si-X3 has two kinds of functionality. The silane portion, Si, joins with the inorganic substrate, that is, with the steel. The union between R, a group of bridge formation, and Si is a very stable organic union, according to the union between X, a hydrolysable group, and the silicon atoms in silane is a less stable inorganic bond and can be replaced by a bond between the inorganic substrate (steel) and the silicon atoms. Because layers formed with steel strips attached from SSL tubing often fail under a combined failure mode, ie, failure of shear / shear strength, it is desirable for bonded steel layers that maintain their shear strength of the leaf, as well as its resistance to detachment under conditions of heat and humidity. To achieve this in a preferred embodiment, the present invention incorporates the use of fiber reinforced continuous fillings in the resin, which are used to join the steel strips. These fillers allow to control the joint thickness, improve the cut resistance of the joint between the steel strips, improve the resistance to release of the union and reduce the contraction of resin matrix as well as increase the resistance of the resin matrix to the cracking Examples of continuous reinforced fiber fillings are made of Kevlar, carbon and glass. These fillers are preferably in the form of webs such as random synthetic webs, such as C-glass webs, and random webs, woven webs such as boat ribbons and ribbons of fiberglass yarns, unidirectional webs, and monofilament meshes. The veils, woven fabrics, ribbons and meshes are all in the form of "ribbon", that is, they are in a continuous layer form. As such, the veils, woven fabrics, ribbons and meshes can be rolled over the steel layers. The veils, woven fabrics, ribbons and meshes can be impregnated with the appropriate resin before winding them around the steel strip tube layer. Alternately, the resin can be applied to a layer of steel strip before winding the veil, woven fabric, ribbon, or mesh, or the resin can be applied over the rolled veil, the woven fabric, the ribbon or the mesh. In addition, instead of using a veil, a woven fabric, a ribbon or a mesh material, the chopped or crushed fibers can be mixed with the resin in an amount that produces a high fiber content before applying the resin on top of a first portion of rolled steel strip layer. Alternatively, the resin can be applied to the rolled steel strip and the crushed or chopped fibers can be applied to the resin. When fiber fillings are used the preferred content of fiber filling is in the order of 30 to 70% by volume. The fibers in the fiber filling serve as a separator that controls the space between the subsequent steel layers and therefore controls the joint thickness between the steel layers resulting in improved peel strength. In an alternate modality, instead of a continuous fiber reinforced fiber, glass spheres, also known as spheres of Z-iron or micro spheres, are used, a discontinuous filling. Due to its spherical shape, the z-iron spheres can compact densely in the resin. The use of fiber reinforced continuous fillers or Z-shaped iron spheres in the resin used to join the steel strips in the SSL pipes improves the life of the pipeline. These fillers can be used to form a resin matrix that is used to join steel strips, which are treated with an adhesion stimulator such as a sol-gel or silane, or steel strips that are sandblasted or sanded. steel strips that are not treated in any way or form. In addition, instead of applying the adhesion stimulator to the steel strips, the adhesion stimulator can be mixed in the resin that is used to join the strips.

Brief Description of the Drawings Figure 1 represents a schematic union of a Fe-O-Si formed between a substrate and a sol-gel coating. Figure 2 is a graph of test results representing the effect of exposure in hot water on the sheet cut sgth of bonded steel strips that are coated with a modified chrome sol-gel and sanded steel strips with sandblasting Figure 3 depicts four examples of formula structures of a hydrolysable group. Figure 4 depicts three examples of structures of non-hydrolyzable organic radical formulas. Figure 5 represents structure of the formula for Vinylotriethoxysilane.

Figure 6 represents a Si-C bond that forms a bridge between an organofunctional silane coating and an epoxy. Figure 7 is a graph of the average sheet shear sgth at 110 ° C (230 ° F) of bonded steel strips that are coated with a chromate-modified sol-gel and bonded steel strips that are coated with an organofunctional silane. Figure 8 is a bar graph comparing the leaf shear sgth of several organofunctional silanes when exposed to hot water at 110 ° C (230 ° F) for different amounts of time. Figure 9 is a table showing the abbreviation, the chemical name and the structure formula of the different components that are incorporated in the organofunctional silanes that are compared in Figure 7. Figure 10 is a schematic view of a process for coating a steel strip with an adhesion stimulator. Figure 11 is a partial side view of a rolled pipe with steel strips representing the different layers of pipe.

Figure 12 is a schematic view of a main roller mechanism that is used in the pipe rolling process. Figure 13 is a graph depicting load-deflection curves for SSL pipes with a tape impregnated with continuous filling between the steel strips and with Z-iron spheres between the steel strips during parallel plate loading. Figure 14 is a table comparing several factors considered when selecting a resin filler. Figure 15 is a table comparing sheet shear sgth, peel sgth and caking times of resin bonded strips incorporating different fillers and which are coated with sol-gel or an organofunctional silane or which is Sand with sandblasting. Figure 16 is a bar graph showing the sheet cut sgth of steel strips coated with an organofunctional silane and which are bonded using a resin and different fillings after different times of exposure to water at 110 ° C ( 230 ° F). Figure 17 is a bar chart comparing the peel sgth of steel strips that are bonded using different fillings and exposed to water at 110 ° C (230 ° F) for different times.

Detailed Description To improve the shear sgth of the sheet between the steel layers in the SSL pipeline, an adhesion stimulator in the form of a sol-gel or organofunctional silane is used to coat the steel strips forming the layers of steel. These adhesion stimulators are used instead of sandblasting the steel strips. The resin, such as EPON 826 resin, still needs to be applied to join the steel strips as it was applied to join the steel strips when sandblasted. In one embodiment, a single-gel coating is used as an adhesion stimulator. Sol is a solution that contains partially reactive metallo-organic precursors (often a metal alkoxide, such as -OSi- (OR) 3 or ROSi (OCxH2x +?) 3) in a solvent, usually alcohol. R is an organic radical that has a functionality that allows the sol-gel coating to bond with the epoxy resin or with other organic resins. The gel is a substance that contains a continuous solid structure that encloses a continuous liquid phase formed by the reaction in the sun. Sol-gel processing involves the preparation of a solid, in a usual manner, a film or coating. Typically, sol-gel is formed by hydrolyzing and condensing the sol solution. Applicants have discovered that chromate-modified sol-gel coating provides better long-term bonding durability in an environment of heat and humidity. Typically, the chromate is introduced into a primer or primer. The primer or primer is then mixed with the sol-gel solution. In a first embodiment, the steel strips are coated with sol-gel. In an alternate embodiment, the strips may be coated with a sol solution and may allow, undergo hydrolysis and condensation to form a sol-gel coating on the strips. Once the sol-gel coating is applied or formed on the strips, a Fe-O-Si bond is formed between the substrate (steel) and the sol-gel coating in the sequence shown in Figure 1. Bridging between the sol-gel coating and an epoxy, such as a resin, is a Si-OR bond that is shown in Figure 1. The bridging between the sol-gel coating and the epoxy, which is used for join the steel in the interpenetrating network (IPN) formed by the Si-OR junction. Applicants further discovered that the use of a sol-gel coating as an alternative surface treatment to the sandblasting of the steel strips provides an improved bonding of the steel strips. For example, the sheet cut strength of the steel strips of the SSL pipe clad with chrome-modified sol-gel joined using EPON 826 / IPD is approximately 40% higher than the cut resistance of the sanded sheet. With sandblasted, uncoated, the strips use the same resin at 110 ° C (230 ° F) (Figure 2). It should be noted that although the test was performed on samples bound with EPON 826 / IPD resin, the present invention is not limited to steel strips that are bonded with EPON 826 / IPD resins, other resins can also be used. Through trials, applicants also discovered that the blade's cut resistance of steel strips coated by chrome-modified sol-gel bonded with EPON 826 / IPD resin at 110 ° C (230 ° F) after 500 hours of exposure to hot water is approximately four times the strength of sand-blasted steel strips bonded with the same resin under the same conditions as shown in Figure 2. In another embodiment, a steel strip is clothes with an organofunctional silane. The organofunctional silane, such as the silane Y-R-Si-X3 or Y- (CH2) n-Si-X3 has two kinds of functionality, ie, this is a bi-functional silane. The silane portion, Si, joins with the inorganic substrate, that is, with the steel. The union between R or a bridging group (CH2) n and Si is a very stable organic union, according to the union between X, a hydrolysable group, and the silicon atoms in silane is a less stable organic union and can be replaced by a union between the inorganic substrate (steel) and the silicon atoms. Typical hydrolyzable X groups include but are not limited to alkoxy, acyloxy, amine, methoxy, ethoxy and chloro. Four examples of structure formulas of the hydrolyzable group X are presented in Figure 3. The organofunctional group, Y, is a non-hydrolyzable organic radical possessing a functionality, which binds or interacts with organic resins such as epoxy resins, which They are typically used to join the steel strips. Examples of non-hydrolysable organic radicals include glycidoxy and amino. Some examples of non-hydrolyzable organic radical formula structures are shown in Figure 4. The bridging between the organofunctional silane coating and an epoxy (eg, resin) is the Si-C bond shown in Figure 6. With some organofunctional silanes such as Vinylotrietoxisilane having the formulas shown in Figure 5, the same group -CH = CH2 (vinyl) forms both the bridging group and the organofunctional group. When the organofunctional silane is used as an adhesion stimulator it can improve adhesion in moisture / dry / thermal with a wide range of substrates. In addition, applicants have found that the use of organofunctional silane as a surface treatment in place of chromate-modified sol-gel produced a leaf cutting resistancy of approximately 10% higher at 110 ° C (230 ° F) without exposure in hot water and approximately 25% and 40% higher at 110 ° C (230 ° F) after 100 and 400 hours of exposure in hot water, respectively, as shown in Figure 7. Examples of organofunctional silanes and their relative resistances under conditions of heat and humidity are shown in Figure 8. As can be seen from the legend in Figure 8, these silanes contain a percentage of one or more of? -Mercaptopropitrimethoxysilane (MPS),? -Glycidoxypropyltrimethoxysilane (GPS), α-Tetraethoxysilane (TEOS), α-Aminopropyltriethoxysilane (APS), and Bis-1, 2- (triethoxysilyl) ethane (BTSE). The structures of the formulas for MPS, GPS, TEOS, APS, and BTSE are shown in Figure 9. A process has been developed by the applicants, which can coat the steel strips with sol-gel or with an organofunctional silane to a speed as high as 1520 cm / min. (50 ft / min). Strip-shaped steel is supplied coated, typically, with shipping oil. The inventive process involves winding the steel strip 11 through a washing drum 10, which contains a washing solution for washing and removing the oils and dirt that comes from the steel (Figure 10). The steel strip is then rolled through a rinsing drum 12, which contains a rinsing solution for rinsing the washing solution off the steel strip. The steel strip is then wound through an air knife 14, which essentially "scrapes" any fluid such as rinsing fluids from the strip. The strip is then rolled through a tank 16 containing sol-gel or silane. The strip is immersed inside the sol-gel or silane. From there, the strip followed through a drying drum 18 where the sol-gel or silane dries on the surfaces of the steel strip. The steel strip then continues through another air knife 20, which "scrapes" the excess sol-gel or silane off the steel strip surfaces leaving a layer of silane or sol-gel on each surface of the strip. the steel strip having a predetermined thickness. From there, the strip is wound inside a roller 22 and is ready to be used in the pipe rolling process. In an alternate embodiment, the sol-gel or organofunctional silane coating is mixed with the resin used to join the steel strips. In order to obtain a good bond between the strips, when mixing the sol-gel or silane with the resin, the steel strips have to be completely clean. Because the layers, which form the joined steel strips of the SSL pipe, often fail under a combined mode of failure, that is, a failure of shear and shear strength, it is desirable that the bonded steel layers maintain its resistance to the cutting of the leaf as well as its resistance to detachment under conditions of heat and humidity. To achieve this, in a preferred embodiment of the present invention, the use of fiber reinforced continuous fillings is incorporated in the resin that is used to join the steel strips and consequently the layers of steel strips. These fillers allow to control the joint thickness, improve the shear strength of the joint between the steel strips, improve the bond release resistance, reduce the resin matrix shrinkage, and increase the resin matrix resistance to cracking. Examples of continuous fiber reinforced fillings are manufactured from Kevlar, carbon and glass. These fillers are, preferably in the form of veils, for example, random synthetic veils, such as C-glass veils, and random veils, manufactured by Reemay and Freudenberg.; woven fabrics such as boat ribbons and ribbons of fiberglass yarns; unidirectional tapes; and monofilament meshes, such as those manufactured by Marquisette and Textie. The veils are formed using chopped fibers which overlap one another and whose ends can be fused or joined together. C-glass veils, for example, consist of chopped glass fibers which are bonded using a starch binder. Because the fibers are fused or joined together, the veils work and are considered continuous fillings with fiber reinforcement. The cost of the veils is typically less than that of woven fabrics which are formed by woven fibers. The monofilament mesh is estimated, typically, similar to the veils. The veils, woven fabrics, ribbons and meshes are all in the form of "ribbon", that is, they are in a continuous layer form which they form and refer to herein as convenience as "continuous fiber filling". As such, the continuous fiber filling can be wound onto the first steel layer formed by the winding of a steel strip. The continuous fiber filling is preferably impregnated with the appropriate resin before being wound around the steel strip pipe layer. This can be achieved by impregnating the resin at the pipe manufacturing site or by acquiring the continuous fiber filling in a pre-impregnated form, ie by acquiring the continuous fiber filling already pre-impregnated with the appropriate resin. Alternatively, the resin can be applied to the steel strip layer before the continuous fiber filling is wound, or the resin can be applied to the continuous fiber-filled roll. The fiber filling content for a continuous fiber filling is, typically, in the order of 30 to 70% of the total fiber and resin combination volume. However, a high content of fiber filling, for example, a fiber filling content at the higher end of this range or larger is preferred. The fibers serve as a separator that controls the space that exists between the subsequent steel layers and therefore controls the joint thickness between the steel layers resulting in improved peel strength. The continuous filling of fiber impregnated with resin can be rolled, simultaneously, with the steel layers at high speeds, which allows higher production speeds (because the winding process will not have to stop for the application of resin between the strips) as it provides a consistent joint thickness across all the layers. In a preferred embodiment, the continuous infill of impregnated fiber is wound onto the inner liner 40 of an SSL pipeline on a mandrel 42 simultaneously with the steel strips to form the SSL pipeline. Preferably, the inner lining of the SSL pipe, I-steel strips, the continuous impregnated fiber filling and the outer lining are wound relatively and simultaneously. For example, by forming an SSL pipe having three layers of steel, the winding of the inner lining on the mandrel is first started. As the inner liner 40 is rolled up, the first strip of steel 44 is wound onto a rolled portion of the inner lining, followed by the winding of a first continuous impregnated fiber backing 46, onto the rolled portion of the first strip of fiber. steel 44, followed by winding the second steel strip 48 over the wound portion of the first continuous fiber filling 46, followed by winding a second continuous impregnated fiber filling 50, followed by winding a third steel strip 52, followed by winding the outer skin of the pipe 54 over the rolled portion of the third steel strip 50. In this respect, the total thickness of the pipe is wound as the winding continues along the length of the mandrel, which is in the direction shown by arrow 56 in Figure 11. To improve the winding process, the steel strips are pre-formed to r pre-arranged with helical winding.

During rolling of the pipe a main roll is used to apply a normal force on the rolled steel strip to remove the excess resin that lies between the strips forming the adjacent steel layers or between the strips and a pipe cladding to better control the joint thickness. The normal force applied by the main roller causes the excess resin that is under a steel strip to be removed from a free edge of the strip. In addition, the normal force applied by the main roller improves the bond between the resin and the steel strip or between the resin and the coating that stimulates adhesion in the steel strip by creating greater loads of surface contact. The entire SSL pipe winding process can be automated as shown in Figure 12. There, a first steel layer 78 is formed by winding a steel strip on a liner formed on a mandrel. A continuous fiber fill 70 is withdrawn from a drum 72 through an impregnation bath 74 containing resin (Figure 12). The continuous filling of impregnated fiber is then wound, helically, onto the mandrel 76 used in the formation of the pipe. A second steel strip 78A is wound, helically, over the continuous filling of impregnated fiber on top of the mandrel. The steel strip is extracted from a drum 79. In the preferred embodiment, an automated process with steel strips of multiple turns on the mandrel is used simultaneously in order of the coating. In other words, the winding of the first strip starts first, followed by the winding of the second strip, and so on up to the fourth strip. For example, a steel strip 78 can be removed from a drum 79 and another steel strip 78A can be extracted from a drum 79A as shown in Figure 12. In this respect, the complete pipe can be rolled in a single step , by means of which the time required to form the pipe is reduced. Four strips of four different drums have been wound up, simultaneously, by the applicants to form SSL pipes. Applicants are currently planning to use ten strips of ten different drums, simultaneously, to roll up a tube. A main roller 80 is used to apply a normal force 82 on each steel strip as it is wound onto a continuous fiber fill impregnated in the mandrel. Typically, the roller is connected with an arm 84, which extends until it is positioned on the mandrel to allow the roller to apply a normal force to the rolled steel strip. The arm is rotatably connected with a device 85 about a pivot point 86. The arm can reciprocate to move the main roller to a position above the mandrel. The arm can be operated, pneumatically, hydraulically or electrically. A vertical member 88 is also rotatably coupled with the pivot point 86 on the device. A front portion 92 of a cylinder 90 is fixed to the member 88 so that the cylinder 90 is in a relatively parallel position with the arm 84. The rear part 94 of the cylinder 90 engages the rear portion 96 of the arm. Once the roller is in position above the mandrel, the cylinder 90 retracts causing the arm 84 to rotate (counterclockwise as shown in Figure 12) and the roller applies a normal force to the strip . Instead of using the mechanism described above, a roller with a predetermined weight could be used as the main roller provides the normal force that is required. The roller can be, by itself, of a predetermined weight or a separate weight can be added to the roller.

In an alternate embodiment, instead of using a continuous fiber filling, chopped or crushed fibers can be mixed with the resin in an amount that produces a high fiber content before applying the resin onto a first portion of the strip layer. rolled steel. Alternately, the resin can be applied to the rolled steel strip and the crushed or chopped fibers can be applied on the resin. Due to the fact that the fibers themselves can carry load, the addition of the fiber fillings to the resin improves the peel strength and the shear strength of the bond between the steel strip layers of the SSL pipe. In addition, the high fiber content reduces shrinkage, and thus, the shrinkage stress developed in the resin during curing improves the bond strength of the resin. In addition, the use of the fiber filler improves the resistance to the growth of cracks in the resin between the layers of steel strips. In essence, the fibers provide a high crack growth. The cracks will grow in the resin until it reaches a fiber where it will stop. The crack can continue to grow in the other portion of the resin and again stop when it reaches another fiber. This phenomenon can be observed in Figure 13, which represents a deflection graph as a load function for an SSL pipeline during loading of the parallel plate made by the ASTM D 2001 standard. As can be seen, the pipe carries charge until a crack develops at a load level 100. As the crack grows with the load application. The load drops to level 102. When it is at load level 102, the crack growth is stopped by means of a fiber and the specimen begins to bring the load back to a load level 104. Another crack begins at grow when it is at point 104 and the load drops to level 106. At level 106 the growth of the crack stops and the specimen begins to carry the load again. In yet a further embodiment, instead of using continuous reinforced fiber fill, glass spheres, also known as Z-shaped spheres of iron or micro spheres, are used as discontinuous fillings. Z-iron spheres are typically made from a ceramic material and are formed as spheres. Z-iron spheres can be hollow or solid. They are manufactured by 3M and Zeelan Industries, Inc. Due to their spherical shape, Z-iron spheres can compact densely in the resin. Preferably, the resin filled with Z-iron spheres should include approximately 7.5% by weight of Z-iron spheres. In laboratory tests, the use of Z-shaped spheres improved the cut resistance between the steel strips in hot conditions (that is, at temperatures of 110 ° C (230 ° F)). However, the carrying capacities of an SSL pipeline formed with steel strips joined with a resin filled with Z-iron spheres was less than the capabilities of an SSL pipeline formed with steel strips attached using a reinforced continuous backfill. fibers which is impregnated with resin (Figure 13). The addition of Z-iron spheres also improves the crack growth resistance of the resin matrix as can be seen from Figure 13. When a resin filled with Z-iron spheres is used, the joint thickness is controlled at use a rubber sweeper. Then, a resin coated with Z-iron spheres is applied to a strip, the excess resin is removed using the rubber sweeper. A main roller can also be used to control the joint thickness and to improve the quality of the joint. In addition, from the performance factors of the union of peel strength and blade shear strength in hot conditions and the retention of blade shear strength in wet conditions, the applicants discovered that other important factors need be considered when selecting a resin filler. These factors are: (1) the resin caking time, that is, the amount of time it takes to remove the excess resin that exists between the strips to maximize bond strength; (2) ease of application of the filling; and (3) the cost of the filling. The caking time and ease of application of the filler affects the production of SSL pipe, in that if the caking times are long and / or if the filling application is difficult, the time and costs associated with the production of SSL pipeline they can become excessive. Figure 14 provides a comparison in relative terms of these factors for woven cloth, monofilament mesh, random synthetic veil, and Z-iron spheres. When the data was applied for this table, it was obtained through the tests. As can be seen from Figure 14, the use of a monofilament mesh allows a very fast resin caking time. However, a joint that is formed with monofilament mesh has a high degradation in cut resistance under wet conditions. The synthetic synthetic veil has a good overall balance in the above factors in that it has a high peel strength, a high cut resistance in hot conditions, a moderate retention of cut resistance in wet conditions, it provides an average time of Caked with resin, it is easy to apply and has a moderate cost. The woven fabric has similar performance characteristics as the random synthetic veil except that it provides longer resin caking times and has high material costs. Z-iron spheres tend to have a low peel strength. The use of fiber reinforced continuous fillings or Z-shaped iron spheres in the resin used to join the iron strips in the SSL pipes improves the pipe's service life. These fillers can be used to form a resin matrix that is used to join steel strips, which are treated with an adhesion stimulator such as sol-gel or silane, or the steel strips are sandblasted or sandblasted. steel strips that are not treated in any way or form. Applicants have discovered, however, that the combination of using an adhesion stimulator such as sol-gel or an organofunctional silane on the steel strip coupled with the use of the filler described herein provides an improved bonding and bonding strength. provides improved retention of resistance to peeling under operating conditions with heat and moisture. From the tests conducted by the applicants the results of which are represented in Figure 15, in this it can be seen that the cut resistance of the joint sheet incorporating Z-shaped iron spheres as a filler between the strips steel at 110 ° C (230 ° F) increased when the steel strips were treated with sol-gel and increased even more when the steel strips were treated with silane. In addition, the retention of the cut resistance in hot and humid conditions also increased from 560 psi after 505 hours of exposure in water at 110 ° C (230 ° F) to 2360 psi and 3280 psi when the strips steel were treated with sol-gel and silane, respectively, and were exposed in hot water at 110 ° C (230 ° F) for 820 hours. A comparison of the leaf cutting resistances at different exposure times in water at 110 ° C (230 ° F) of the steel strips which are coated with an organofunctional silane and are joined using either Z-type G-800 iron spheres, a Freudenberg veil 723020, or a Reemay veil type 2270; which are shown in Figure 16. As can be seen from Figure 16, the use of the Reemay and Freudenberg veils significantly increased the resistance to detachment of the union to a low exposure in hot water, as it is shown in Figure 16, with acceptable increases in times of resin caking. Although the present invention has been described and illustrated with respect to the multiple modalities thereof, it is understood that it will not be limited, since changes and modifications can be made to this document, which are within the total scope of the invention. this invention is intended as claimed below.

It is noted that in relation to this date, the best method known by the applicant to carry out the aforementioned invention is that which is clear from the present description of the invention.

Claims (35)

1. Claims Having described the invention as above, the content of the following claims is claimed as property: 1. A method for forming a laminated pipe, characterized in that it comprises the steps of: forming at least a portion of an inner layer of the pipe; coating a first stof steel with a sol-gel coating; roll the steel stover the inner layer; and forming an outer layer on the rolled steel st 2. A method according to claim 1, characterized in that it further comprises the steps of: coating a second steel stwith a sol-gel coating; and winding the second steel stover a rolled portion of the first steel st 3. A method according to claim 2, further characterized in that it comprises the step of: forming a layer comprising resin between the two rolled steel st. 4. A method according to claim 3, wherein the step of coating comprises the step of forming the sol-gel coating, characterized in that the step of forming the sol-gel coating comprises the steps of: forming a solution containing a precursor partially reactive metallo-organic; hydrolyze the solution; and condense the solution. 5. A method according to claim 3, further characterized in that it comprises the step of: mixing the chromate in the sol-gel. A method for forming a laminated pipe, characterized in that it comprises the steps of: forming at least a portion of an inner layer of the pipe; coating a first stof steel with a coating of silane; roll the steel stover the inner layer; and forming an outer layer on the rolled steel st 7. A method according to claim 6, characterized in that it further comprises the steps of: coating a second steel stwith a silane coating; and winding the second steel stover a rolled portion of the first steel st A method according to claim 7, further characterized in that it comprises the step of: forming a layer comprising resin between the two rolled steel st. 9. A method according to claim 8, characterized in that the resin is an organic resin, wherein the silane comprises YR-Si-X3, where the Si joins the surfaces of the steel st where R is a group of bridge formation, and where Y is a non-hydrolyzable organic radical that interacts with the resin. A method for forming a laminated pipe, characterized in that it comprises the steps of: forming an inner lining of the pipe; forming a first steel layer having an inner surface and an outer surface on the coating; joining a second inner surface of the steel layer with the first steel layer using an adhesion stimulator mixed with a resin; and forming an outer coating on the second steel layer. 11. A method according to claim 10, characterized in that the adhesion stimulator is selected from the group of adhesion stimulators consisting of sol-gel and silane. 12. A method for coating a stof material with an adhesion stimulator, characterized in that it comprises the steps of: passing the stthrough a washing fluid; passing the stthrough a rinsing fluid to rinse the wash solution off the st passing the stthrough an adhesion stimulator solution; and drying the solution of the adhesion stimulator on the st 13. A method for coating a stof material with an adhesion stimulator, characterized in that it comprises the steps of: passing the stthrough a washing fluid; passing the stthrough a rinsing fluid to rinse the wash solution off the st pass the stthrough an air knife to remove excess fluids from the strip; pass the strip through a sol-gel solution; pass the strip through a dryer to dry the sol-gel on the strip; and passing the strip through a second air knife to remove the excess adhesion stimulator from the strip to obtain a coating of the adhesion stimulator on the strip having a predetermined thickness. 14. A laminated pipe, characterized in that it comprises: an interior lining that defines an interior surface of the pipe; a first layer of steel formed on the inner lining. a second steel layer bonded onto the first steel layer, wherein at least one of the first and second steel layers is coated with a sol-gel coating to ensure the bonding of a steel layer; and an outer coating on the second steel layer defining an outer surface of the pipe. 15. A laminated pipeline according to claim 14, characterized in that the sol-gel coating comprises a partially reactive metalloorganic precursor. 16. A laminated pipeline according to claim 14, characterized in that the sol-gel coating comprises chromate. 17. A laminated pipe, characterized in that it comprises: an inner lining defining an interior surface of the pipe; a first steel layer formed on the inner lining; a second steel layer bonded onto the first steel layer, wherein at least one of the first and second steel layers is coated with a silane coating to ensure the bonding of a steel layer; and an outer coating on the second steel layer defining an outer surface of the pipe. 18. A laminated pipeline according to claim 17, characterized in that the silane comprises: silicon; a hydrolysable group; and an organic non-hydrolysable radical. 19. A laminated pipe, characterized in that it comprises: an inner lining defining an interior surface of the pipe; a first steel layer formed on the inner lining; an intermediate layer comprising resin and a fibrous filler on the first steel layer; a second steel layer bonded to the first steel layer by means of an intermediate layer; and an outer coating formed on the second steel layer defining an outer surface of the pipe. 20. A laminated pipe according to claim 19, characterized in that the intermediate layer comprises fibrous material selected from the group of materials consisting of glass, carbon and Kevlar. 21. A laminated pipe according to claim 19, characterized in that the intermediate layer comprises chopped fibrous material. 22. A laminated pipe according to claim 19, characterized in that the intermediate layer comprises a continuous layer of reinforced fiber. 23. A laminated pipe according to claim 22, characterized in that the continuous layer of reinforced fiber is of the form selected from the groups of shapes consisting of veils, woven fabrics, ribbons and monofilament meshes. 24. A laminated pipe according to claim 19, characterized in that at least one of the steel layers is coated with an adhesion stimulator before joining. 25. A laminated pipe according to claim 24, characterized in that the adhesion stimulator is selected from the group of adhesion stimulators consisting of sol-gel and silane. 26. A method for forming a laminated pipe, characterized in that it comprises the steps of: forming at least a portion of an inner lining; winding a first strip of steel on the inner lining that forms a first layer of steel; forming a fibrous layer on the first steel layer; winding a second strip of steel over the fibrous layer that forms a second layer of steel; and forming an outer coating on the second steel layer. 27. A method according to claim 26, characterized in that the step of forming a fibrous layer comprises the step of forming a layer which in turn comprises resin and chopped fibers. A method according to claim 26, characterized in that the step of forming a fibrous layer comprises the step of wrapping a reinforced fibrous continuous layer over the first steel layer. 29. A method according to claim 26, further characterized in that it comprises the step of applying a sol-gel or silane coating to at least one of the steel strips. 30. A method in accordance with the claim 26, further characterized in that it comprises the step of applying sol-gel or silane to the fibrous filler. 31. A laminated pipe, characterized in that it comprises: an inner lining defining an interior surface of the pipe; a first steel layer formed on the inner lining, the first steel layer has an outer surface; a layer of glass spheres on the first steel layer; a second layer of steel joined with the glass spheres; and an outer coating formed on the second steel layer defining an outer surface of the pipe. 32. A laminated pipeline according to claim 31, characterized in that the layer of glass spheres comprises a resin and a sol-gel or silane. A method for forming a laminated pipe, characterized in that it comprises the steps of: forming at least a portion of an inner lining; winding a first strip of steel over the inner lining that forms a first layer of steel; forming a layer of glass spheres on the first steel layer; roll a second steel strip over the fibrous layer that forms a second layer of steel; and forming an outer coating on the second steel strip. 34. A method according to claim 33, characterized in that the first steel strip has an outer surface that orients the layer of glass spheres, and where the second steel strip has an inner surface that orients the layer of spheres of glass. glass, the method further comprises the step of applying 'sol-gel or silane to at least one of the surfaces. 35. A method in accordance with the claim 33, characterized in that the step of forming a layer of glass spheres comprises the steps of: forming a mixture of glass spheres, resin and sol-gel or silane; and apply the mixture on the first layer.