Patent Application
20070240816
These figures are not drawn to scale and are intended only for illustrative purposes. While the invention is amenable to various modifications and alternative forms, specifics thereof have been shown by way of example in the drawings and will be described in detail. It should be understood, however, that the intention is not to limit the invention to the particular embodiments described. On the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the scope of the invention as defined by the appended claims.
Aspects of the present invention relate to a protective cover for girth-welds having an air release mechanism. In an exemplary embodiment, a heat recoverable polymer material (such as a heat shrink sleeve or sheet) having a plurality or matrix of holes is provided to be placed over a girth-weld that can facilitate air release during the shrinking process. The porous structures (e.g., holes extending through the inner and outer surfaces of the heat recoverable polymer sheet) will automatically direct air out of the sleeve as the heat shrink sleeve is activated (e.g., by shrinking). This process can prevent entrapped air from remaining trapped underneath the protective cover. In a preferred aspect, as the sheet or sleeve is shrunk, an adhesive material (e.g., a hot melt adhesive or a mastic) can flow through the porous structures after all the air is removed from the system. With the adhesive material now filling the plurality of holes, a protective layer is reestablished, thus preventing penetration of external elements (e.g., water). The adhesive flow can also act as an indicator of correct installation. For example, the adhesive can be a color different from that of the sheet or sleeve. An indicator can thus be a contrasting color visible on a top surface of the sheet or sleeve (e.g., a pattern of different color dots would appear) when the installation is complete. Additionally, the porosity and contrasting protective media can reduce the cathodic shielding normally seen in a typical heat shrink sleeve, whereby the adhesive could be modified to be more conductive.
A first aspect of the present invention is shown in
Pipe ends 101, 102 can be formed from a standard pipe material, such as steel. Pipe ends 101, 102 also include an outer coating 106 that can comprise a conventional protective coating, such as a polyolefin-based coating. In an exemplary embodiment, protective coating 106 comprises a three-layer coating having an epoxy, an adhesive and a polyolefin top coat that are melt-fused together on the pipe ends 101, 102. As would be understood by one of ordinary skill in the art given the present description, other formulations of protective coatings, such as two-layer coatings, and those described in J. A. Kehr, “Fusion-Bonded Epoxy (FBE): A Foundation for Pipeline Corrosion Protection”, NACE Press (Houston, Tex.), 2003 (see e.g., Chapter 4 and pages 234-246) (incorporated by reference herein), can also be utilized as the protective coat 106.
As is also shown in
As shown in
As shown in
The heat recoverable polymer material 120 can comprise a pre-expanded EPDM rubber or cross-linked polyethylene materials. Other example materials that can be used to form heat recoverable polymer material 120 includes those described in U.S. Pat. No. 6,015,600, and commercially available materials such as are available from Raychem (e.g., model WPCT M05106).
Further, an inner surface of the heat recoverable polymer material 120 can optionally be coated with an adhesive layer or coating 122 to help further bond the heat recoverable polymer material 120 to the pipe ends 101, 102. For example, the adhesive layer 122 can comprise a mastic or hot melt material. In one exemplary embodiment, the adhesive or coating 122 can have a color different from the color of the heat recoverable polymer sheet 120. Alternatively, adhesion of the heat recoverable polymer material 120 to the girth-weld region can be accomplished using corrosion coating 108.
In operation, a girth-weld is formed in the field by joining pipe ends 101 and 102. After welding, optionally, the girth-weld area can be further cleaned. Additionally, a field-applied corrosion coating 108 can be applied to the girth-weld. This optional coating 108 can be a liquid epoxy, such as Scotchcast 323 available from 3M Company, St. Paul, Minn.
After the optional corrosion coating 108 is applied and/or at least partially cured, heat recoverable polymer sheet 120 having a plurality of holes 124 is disposed (e.g., wrapped) over the girth-weld 104. As mentioned above, in an exemplary embodiment, an inner surface of the heat recoverable polymer sheet 120 is coated with an adhesive layer 122.
To conform the heat recoverable polymer material 120 to the surface of the girth-weld region, heat is applied (e.g., via a hot air gun or torch) to material 120. In one exemplary embodiment, the protective sleeve is wrapped around the pipe (to cover the girth-weld), then sealed longitudinally (e.g., by heating the overlap region). The sleeve can then be shrunk by applying heat. A technician, for example, can start at the center of the sleeve (with the weld seam being directly underneath the sleeve) and can seal the sleeve around the pipe by heating radially, working outward (longitudinally) from the middle, while alternating in each direction, to completely shrink the sleeve.
As the heat recoverable polymer material 120 is shrunk, air trapped underneath can be released through holes or pores 124 formed in sheet 120. As shown in
This exemplary embodiment can reduce or eliminate undesirable bubbles and wrinkles that often form under protective covers, helping to ensure more optimal conformity to the weld. Further, the above method and system can reduce the likelihood of incomplete installation, as the bubbles formed during shrinking can be visually monitored in a straightforward manner. Moreover, different colors for the adhesive and heat recoverable polymer material 120 can be selected to provide greater visual contrast as bubbles form in the plurality of holes to indicate the completion of the process.
In another embodiment, the adhesive 122 can be modified to have some conductive properties, for example, by chemically modifying the adhesive with polar groups (e.g. maleated polyolefin) or by adding conductive nanoparticles to the adhesive. As the adhesive 122 is designed to penetrating the sleeve 120 through holes 124, this arrangement can provide for the current to flow to ground and reduce the shielding effect of the bulk sleeve.
While the present invention has been described with a reference to exemplary preferred embodiments, the invention may be embodied in other specific forms without departing from the scope of the invention. Accordingly, it should be understood that the embodiments described and illustrated herein are only exemplary and should not be considered as limiting the scope of the present invention. Other variations and modifications may be made in accordance with the scope of the present invention.
This application claims the benefit of U.S. Provisional Patent Application No. 60/744,966, filed Apr. 17, 2006, the disclosure of which is incorporated by reference herein in its entirety.
| Number | Date | Country | |
|---|---|---|---|
| 60744966 | Apr 2006 | US |
