METHOD TO INSTALL A WEAR-RESISTANT POLYMER SLEEVE IN A METAL PIPE BEND STIFFENER

Abstract

This invention offers a method to install a wear-resistant polymeric sleeve in a pipe bend stiffener with a metal inner wall, including the following steps: calculate thickness of the internal wall of the stiffener that can removed; remove the thickness of at least a portion of the calculated inner wall; and apply a polymeric material sleeve in the inner wall of the stiffener, where the polymeric material sleeve has the thickness of the inner wall removed.

Claims

1. Method to install a wear-resistant polymeric sleeve in a metal pipe bend stiffener, characterized by the following steps calculate the thickness of the internal wall of the stiffener that can be removed; remove the thickness of at least a portion of the calculated inner wall; and apply a polymeric material sleeve in the inner wall of the stiffener, where the polymeric material sleeve covers the dimensions of thickness of the inner wall removed.

2. Method according to claim 1, characterized by including the step of treating the internal wall of the stiffener, before the step of applying the polymeric material sleeve to the internal wall of the stiffener.

3. Method according to claim 1, characterized by the step of calculating the thickness of the internal wall of the stiffener that can be removed, including modeling the stiffener by a software tool, and analyzing the stiffener structure by the finite elements method.

4. Method according to claim 1, characterized by the step of removing the calculated inner wall thickness including a machining process.

5. Method according to claim 1, characterized by including the step of replacing anticorrosive protection on the surface of the metallic stiffener that has undergone the step of removing the calculated thickness of the inner wall.

6. Method according to claim 1, characterized by including the step of performing a non-destructive test on at least one of the following: the metallic stiffener; and the polymeric material sleeve after the step of removing the calculated thickness of the inner wall.

7. Method according to claim 6, characterized by including non-destructive testing, including use of at least one of the following: ultrasound; and penetrating liquid.

8. Method according to claim 1, characterized by the polymeric material being polyurethane.

9. Method according to claim 1, characterized by the step of applying a polymeric material sleeve in the inner wall of the stiffener, including manufacturing a mold for the polymeric material sleeve, assembling the mold in the stiffener, and casting a polymer in the mold, where the temperature throughout the process is controlled.

10. Method according to claim 1, characterized by a step to remove the calculated thickness of the inner wall, removing at least 10 mm of thickness of the inner wall of the metal stiffener.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0019] The detailed description given below is for the accompanying figures and the respective reference numbers, representing the modalities of this invention.

[0020] FIG. 1 illustrates the metal part of a common stiffener, without an inner liner, used in the prior art.

[0021] FIG. 2 shows a FIG. 1 stiffener after undergoing the installation method of a wear-resistant polymeric sleeve of this invention.

DETAILED DESCRIPTION OF THE INVENTION

[0022] First, note that the following description will start with the preferred embodiment of the invention. As will be apparent to one skilled in the art, however, the invention is not limited to this particular embodiment.

[0023] In addition, note that this report will use both the term pipe, as well as the term riser, to refer to the flexible line element. These terms are commonly used by anyone skilled in the art so that, indeed, the use thereof is not likely to cause confusion.

[0024] As discussed above, the use of pipes (risers) with stiffeners without liners, is well established in the prior art. However, due to friction between these elements, the pipe must be frequently inspected to assess the amount of wear to the outer layer, because normally the pipe suffers premature wear in the area in contact with the stiffener metal.

[0025] When wear becomes critical, namely there is a risk to the structural integrity of the pipe, a process called re-terminating must be performed, which basically consists of cutting a portion of the end of the flexible line (riser) and installing a new connector. However, when there is not sufficient length for this procedure, a new structure must be acquired and the damaged riser must be replaced.

[0026] Both solutions are expensive and do not solve the problem of pipe wear, they only renew the short service life of the element.

[0027] Another option would be to replace the stiffener without a liner with a new model, such as a stiffener with a polymeric liner. However, this solution is not always feasible, due to the large dimensional differences between the risers used and a new stiffener, in addition to the load limitations of the platforms on which the risers are installed. In addition, replacement of the stiffeners in question would be very costly.

[0028] Thus, this invention solves the prior art problem, so as to allow a metallic stiffener to be reworked, allowing for the installation of a sleeve with polymeric material inside. Thus, metal-riser friction is eliminated, since the polymeric material sleeve will be in contact with the riser, and not with the metal stiffener, reducing damage to the outer casing of the riser.

[0029] Thus, the installation of a polymeric sleeve in a metallic stiffener of an older model increases the useful life of the riser, reducing the rate of wear between the outer casing of the riser and the inner surface of the stiffener. Thus, loss of production due to re-termination or replacement of the riser is considerably reduced.

[0030] To this end, this invention provides a method to install a wear-resistant polymeric sleeve on a metallic pipe bend stiffener involving the following steps: calculate a thickness value of the internal wall of the stiffener that can be removed; remove the thickness of at least a portion of the calculated inner wall; and apply a polymeric material sleeve on the inner wall of the stiffener, where the polymeric material sleeve covers the thickness of the inner wall removed.

[0031] After various studies, it was possible to calculate the thickness of the inner wall of the stiffener that could be removed to apply the sleeve, so that, preferably, removal of thicknesses greater than 10 mm is required so that applying the sleeve directly on the inner surface of the stiffener is feasible.

[0032] This invention provides that the thickness of at least a portion of the inner wall of the stiffener is removed, and situations are provided for in which the thickness of the inner wall as a whole is removed at least in part, and situations where only one part of the inner wall has thickness removed.

[0033] Thus, the step of calculating the thickness of the internal wall of the stiffener that can be removed can determine the technical feasibility of the proposed modification, and the maximum thickness that can be removed from the internal diameter of the stiffener without compromising its mechanical strength was verified. For a more accurate assessment at this stage, the stiffener is optionally numerically modeled by a computational tool and its structure is analyzed by the finite elements method.

[0034] After calculating the thickness to be removed, and deciding that the stiffener can go through the process of removing thickness as described, it is dismantled and its parts are inspected to check the integrity of such components. In this step, the stiffener is disassembled component by component, and the possibility of reusing each part is assessed. In cases of very damaged components, such components are replaced.

[0035] Optionally, drawings are made of the new configuration of the stiffener, with the polymeric material sleeve. This drawing may include details on each component and the drawing of the already assembled final group.

[0036] Thus, the step of removing the thickness of at least a portion of the calculated inner wall is carried out. At this point, the stiffeners preferably go through a machining process, the complexity of which may depend on the geometry and finish specified for each case.

[0037] Optionally, in order to increase the strength of the stiffener, the elements undergo surface treatment of the metal parts to restore corrosion protection. At this stage, chemical and/or mechanical treatments (painting) can be applied to the still dismantled components, and these treatments may follow the type of coverage used in the original stiffener design.

[0038] Another option is to include a non-destructive testing step for the stiffener and/or polymeric material sleeve. In this step, the stiffener and/or polymeric material sleeve are subjected to traditional non-destructive testing such as: ultrasonic, liquid penetrant and/or other testing necessary to assess the integrity of manufactured or refurbished parts.

[0039] Thus, a step of applying a polymeric material sleeve in the inner wall of the stiffener is included, where the polymeric material sleeve covers the thickness of the removed inner wall. Optionally, a mold is manufactured and assembled inside the stiffener, so that after the polymer is cast and cured it will meet the planned dimensions of the polymeric material sleeve, without any adjustments after this step. Optionally, the polymeric material sleeve may be pre-manufactured, and simply adhered to the inner surface of the stiffener.

[0040] If the polymeric material sleeve is directly molded on the inner surface of the stiffener, the polymer, which may be polyurethane, is cast in the mold, and the temperature throughout the process is controlled to prevent any internal or surface imperfections and also to ensure perfect adherence of the polymeric material sleeve to the metal body of the stiffener.

[0041] After applying the polymeric material sleeve, all parts are properly brought together and assembled, following the torques recommended by the stiffener manufacturer. After assembly, the whole is measured, based on the values determined by the design drawings.

[0042] Finally, in order to guarantee the tracking process, documentation of all of the processes involved in reworking the stiffener are gathered. This documentation must include the detailed designs of the components, the assembly drawing, the certificate of the materials used to recreate parts considered necessary parts and other labor certificates and certificates for consumables used in the process.

[0043] FIG. 1 shows a common metal stiffener 1, known from the prior art. FIG. 2 illustrates metal stiffener 1 in FIG. 1 after undergoing a method of installing a wear-resistant polymeric sleeve 2 in a metal pipe bend stiffener 1 of this invention. Note in FIG. 2, that stiffener assembly 1, polymeric material sleeve 2 does not show increased thickness when compared to stiffener 1 in FIG. 1.

[0044] Thus, it is clear that the installation method of a wear-resistant polymer sleeve in a metal pipe bend stiffener shown here resolves the problems of the prior art, allowing for refurbishing of a common metallic stiffener, reducing (or doing away with) metal/pipe friction without the high costs of replacing the entire stiffener.