Patent Application
20070241558
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. After the girth-weld is formed (and optionally cleaned), a corrosion (protection) coating is applied in the field to the girth-weld. Before the corrosion coating cures or sets, a protective cover is then disposed over the girth-weld. In one aspect, the protective cover is a multilayer material having a first structured layer that mechanically couples to a corrosion coating coated thereon, where the corrosion coating permeates a substantial portion of the first structured layer. The multilayer cover material also includes a second layer comprising a polymer layer adhered to the first layer, where the second layer protects the corrosion coating and girth-weld from damage.
In an alternative aspect, after the girth-weld is formed, a protective cover is disposed over the girth-weld. This protective cover includes an injection system that provides for the corrosion coating to be applied to the girth-weld after the protective cover is positioned and disposed over the girth-weld. In a preferred aspect, as the corrosion coating is being injected onto the girth-weld area through the protective coating, excess coating can flow through bleed holes formed in the protective coating to provide an indication of completion of the installation process.
Further, in both the alternative aspects, full installation of the protective cover system can be accomplished without the need for an external heat source. More details are provided below.
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
In addition, flexible protective cover or sheet 120 can include a second layer (or outer surface) 124 that provides impact protection for the girth-weld 104. For example, layer 124 can comprise a polymer material (e.g., polypropylene or polyethylene) having suitable toughness. Layer 124 can be bonded or adhered to layer 122 in a conventional manner (e.g., lamination).
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.
After the corrosion coating 108 is applied and/or partially cured, the flexible protective cover or sheet 120 is disposed (e.g., wrapped) over the girth-weld 104. Optionally, the sheet 120 is provided in roll form and the adjoining wrap ends or edges can be coupled or sealed together using a mechanical fastener. Preferably, the sheet 120 is wrapped about the girth-weld such that the inner surface of the sheet 120 contacts a substantial amount of the newly applied or partially cured corrosion coating 108.
As mentioned above, in an exemplary embodiment, an inner surface of the flexible protective cover or sheet 120 is structured (e.g., with hooks or fibers), thus providing for a mechanical bonding with the corrosion coating 108 as it further cures, to anchor the sheet 120 into the underlying corrosion coating. In addition, as the corrosion coating is not yet fully cured, in a preferred aspect, as the flexible sheet is wrapped around the girth-weld, a substantial portion of the first layer is permeated by the corrosion coating, thus allowing the flexible cover 120 to better bond to the surface of the girth-weld region. The flexible protective cover or sheet 120 does not require the use of an external heat source (e.g., a hot air gun or a propane torch) to create a bond between the protective sheet and the girth-weld region of the pipeline or system.
Thus, in this aspect, a no-heat weld wrap can be utilized as an alternative to a heat shrink sleeve. The sheet's mechanical structures can anchor the sheet into the underlying corrosion coating to help prevent the sheet 120 from slipping under soil stresses.
An alternative aspect of the present invention is shown in
As shown in
In addition, cover 220 can further include one or more bleed holes 225 formed therethrough. The holes 225 can be formed in cover 220 through a standard technique, such as a mechanical process (e.g., drilling, puncturing, etc.), focused radiation (e.g., laser, or other), or thermal process.
In one aspect, protective cover 220 comprises a flexible polymer (such as a polyolefin material) sheet that is secured in place around the girth-weld via, e.g., a mechanical fastener, an adhesive, and/or a clamp. Alternatively, the protective cover 220 can comprise a more ridged polymer that has been shaped or molded to fit around the weld. In another aspect, the protective cover 220 is formed from a substantially transparent material.
In operation, a protective cover 220 is placed around the girth-weld. The cover 220 can then be secured down to the mainline pipe coating via a clamp, a fastener, or the like. A liquid corrosion coating is then delivered to the girth-weld area or the pipe. Preferably, the corrosion coating is injected through port 226 at the (relative) bottom of the cover 220 to completely fill the space between the pipe and the wrap. As the space enclosed by cover 220 is filled with the corrosion coating, air is pushed out of the system. When full, the corrosion coating may begin to seep out of the bleed holes 225, indicating completion. In preferred aspects, the corrosion coating has a color different from the color of the protective cover, thus providing a more visual indication of completion of the process as the corrosion coating may begin to seep out of the bleed holes 225 or as the installer sees the corrosion coating (through a substantially transparent cover) spreading over the girth-weld region.
As with the embodiment of
Further, corrosion coating and protective cover 220 can be provided to an installer as a kit that could include the protective cover, a pre-measured bag or other container of liquid corrosion coating, (optionally) a pump, and a hose that could attach to port 226.
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. 60/744,961, filed Apr. 17, 2006, the disclosure of which is incorporated by reference herein in its entirety.
| Number | Date | Country | |
|---|---|---|---|
| 60744961 | Apr 2006 | US |
