Patent Application
20160279865
The present invention relates generally to polyolefin pipes and other structures, and more particularly relates to a method and apparatus for repairing and/or joining polyolefin pipes and other structures.
Polyolefin materials include the following: thermoplastic polyolefins: polyethylene (PE), polypropylene (PP), polymethylpentene (PMP), polybutene-1 (PB-1); Polyolefin elastomers (POE): polyisobutylene (PIB), ethylene propylene rubber (EPR), ethylene propylene diene monomer (M-class) rubber (EPDM rubber). Such materials, especially in a tubular configuration (i.e., pipes), are utilized to deliver or convey an assortment of media that may have corrosive chemical properties. PE and PP pipe is commonly used by gas utility companies, for example. Such pipes themselves may be deployed in environments that also subject the exterior of the pipe to corrosive or otherwise physically or chemically damaging conditions. Polyolefins are also materials from which various other types of structures, such as holding tanks, pressure vessels and the like, which may be deployed in harsh environments.
When deploying polyolefin pipe in a particular application, it is of course frequently necessary to join two sections of pipe together end-to-end. One method of accomplishing this is by welding the pipe sections together. In a common technique known as butt fusion, the two pipe sections are heated by a welding plate in the form of a heated disk to cause the ends of the pipes to become molten. The welding plate is then removed and the pipe sections are pressed together with some predetermined force for some predetermined duration of time, depending upon wall thickness and pipe diameter. The result is a weld joint that typically has a circumferential bead cap. There are known potential problems with such weld joints, due to stress differentials and the like that may exist in the heat-affected zone. Weld joints are susceptible to cracking over time, either due to external forces, such as soil movement or physical impact, or due to the material becoming brittle over time.
There are also various types of field connections that may be made to polyolefin pipe. These include couplings such as tees, elbows, reducers, and so on. Field connections typically employ some form of crimping force to squeeze the joints together. This crimping process is known to introduce micro-cracks in the pipe material. These micro-cracks can grow over time, due to cyclic pressures, exposure to temperature swings, material embrittlement, and so on, leading to failure or leaks.
Persons of ordinary skill in the art will appreciate that polyolefins are materials that by their very nature are difficult to bond to, due to their molecular density and low surface energy. This prevents most simple methods of bonding most types of materials to a polyolefin surface from being entirely effective. Consequently, there has heretofore been little that could be done to repair polyolefin structures that have become degraded by mechanisms such as described above. Pipes may exhibit mechanical damage, including the growth of micro-cracks that can be induced from crimp connections. Of course, this is undesirable where such defects could allow for leaking, posing dangers to individuals or the environment.
In view of the foregoing and other considerations, the present invention is directed to a method and apparatus for repairing polyolefin structures, particularly (but not exclusively) PE or PP pipe. In one embodiment of the invention, a damaged area of a polyolefin pipe has filler material applied thereto as necessary to fill cracks, voids, or other degradation of the pipe. Following application of a filler material, a transitional film is applied over the area being repaired. The transitional film has a first side that is adapted to bond to polyolefins. The bonding process may involve application of heat and/or compressive force. After the transitional film is applied and bonded, a reinforcement system, such as a fiber-reinforced polyurethane application, is applied over the repair area to complete the repair process.
In another embodiment of the invention, a butt weld joint is repaired or reinforced. In some cases, it may be necessary to prepare the joint by smoothing or eliminating the bead cap formed during the welding process. In this embodiment, no filler material may be necessary. The transitional film as described above is applied over the joint and bonded to the joined segments of pipe. Thereafter, a reinforcement system is applied over the transitional film to complete the repair or preventative reinforcement of the weld joint.
In another embodiment of the invention, a crimped area, such as at a field connection, is repaired or reinforced, in a manner similar to that described above for repairing or reinforcing a butt weld.
The present invention is best understood with reference to the following detailed description of embodiments of the invention when read in conjunction with the attached drawings, in which like numerals refer to like elements, and in which:
In the disclosure that follows, in the interest of clarity, not all features of actual implementations are described. It will of course be appreciated that in the development of any such actual implementation, as in any such project, numerous engineering and technical decisions must be made to achieve the developers' specific goals and subgoals (e.g., compliance with system and technical constraints), which will vary from one implementation to another. Moreover, attention will necessarily be paid to proper engineering practices for the environment in question. It will be appreciated that such development efforts might be complex and time-consuming, outside the knowledge base of typical laymen, but would nevertheless be a routine undertaking for those of ordinary skill in the relevant fields.
Referring to
Once the filler material has been applied and cured or otherwise hardened, a next step in accordance with the disclosed embodiment of the invention is to overlay a transitional film 16 over the section of pipe being repaired. This is shown in
A preferred attribute of the transitional film 16 is that it is adapted on one side thereof to bond effectively with polyolefinic materials, such as PE, EVA, EPOM, and PP and adapted on the opposite side thereof to bond to PVC, polyurethane, ABS, PC, PA, etc.
In an exemplary embodiment, the transitional film is wrapped around the length of pipe 10 being repaired. Those of ordinary skill in the art will recognize that the bonding of film 16 to pipe 10 must be activated. Typically, this is accomplished by means of application of heat and compressive force. One method of accomplishing this is through the use of heat-activated shrink tape (not shown in the Figures), such as 220R 4″ 20% shrink release coated roll commercially available from Dunston Inc., headquartered in Charlotte, N.C., United States. See www.shrinktape.com.
Once film 16 has been bonded to pipe 10 over the area being repaired, an outer reinforcement system 18 is applied over the repair area, as shown in
In addition to providing a means of effectuating structural repair of polyolefin structures such as PE pipes, as described above with reference to
In particular, in
It is further contemplated that the present invention may be employed as a preventative measure to strengthen the integrity of a conventional butt fusion joint between two sections of pipe.
Turning to
As shown in
As described above, the next step 42 is to apply filler material as necessary to provide a relatively smooth repair surface. This step 42 may or may not be necessary depending upon the nature of the damage being repaired. As noted above, suitable filler materials may be a polyester, epoxy, vinyl ester, polyurethane, thermoplastic material, rubber compound, or acrylic, such as a methylacrylate or thermoplastic material.
The next step 44 is to apply the bi-material coextruded transitional film to the repair area. In one embodiment, bonding of the transitional film to the repair area is accomplished by applying heat, such as with a heat gun or the like, as represented by block 46.
Next, in block 48, a reinforcement system is applied over the repair area. The aforementioned A+ Wrap™ or FormaShield™ systems are candidates for the reinforcement system.
Next, in block 50, compressive force is applied to the repair area. As noted above, one manner of accomplishing this is through the use of heat-shrinking tape that is wrapped around the tubular member being repaired and then applying heat, such as with a heat gun, to cause the tape wrap to constrict or compress around the tubular member and the repair area.
As noted in block 52, the reinforcement system is allowed to cure, at which time the means of applying compressive force (e.g., the heat-shrink tape) may be removed.
Turning now to
In block 60, the hi-material, co-extruded transitional film is applied, as hereinbefore described. Heat is the preferred method of bonding the transitional film to the repair area, as reflected by block 52. Thereafter, a reinforcement system as described above is applied.
In the embodiment of
A vacuum bag pressure system is employed to exert compression force on the repair area as the reinforcement system is curing. In block 70 of
In block 72, vacuum pressure is applied to compress the vacuum bag against the repair area. This compression force is maintained for as long as it takes for the reinforcement system to cure, typically two to four hours.
Referring now to
The transitional film 24 and the reinforcement system 26 can be any of the transitional films 24 and the reinforcement systems 26 described in relation to any of the other embodiments.
When the respective ends of the tubular members 20, 22 are placed within the couple 110, which defines the coupler joint (the couple joint contains the coupler and the portion of the tubular members within the coupler). Preferably, when the transitional film 24 is applied and bonded to the coupler 110 and at least a portion of the at least two tubular members 20, 22 it is wrapped around the coupler 110 and the tubular members 20, 22. The wrapping of the transitional film 24 preferably completely covers the coupler 110. The wrapping of the transitional film 24 preferably extends onto the tubular members 20, 22 at least about 0.5 inch more preferably 1 inch past the end of the coupler.
In one embodiment, the bonding of the transitional film to the respective ends of the tubular members comprises applying heat to the transitional film. In one embodiment, the bonding of the transitional film to the respective ends of the tubular members comprises wrapping the pipe with heat-activated shrink tape and heating the damaged area to activate a bonding process of the transitional film to the respective ends of the tubular members.
In one embodiment, applying a reinforcement system over the transitional film comprises wrapping the reinforcement system over the transitional film. In one embodiment, less than 100% or less than 90% of the surface area of the transitional film is covered by the reinforcement system. In another embodiment, essentially all of the surface area of the transitional film is covered by the reinforcement system. “Essentially all” in this application is defined to be at least 95%. In another embodiment, the reinforcement system covers essentially all of the surface area of the transitional film and at least a portion of the tubular members outside of the transitional film area.
The coupler may be made of any suitable material such as metal, or a polymer. It may be made of the same or different materials than the tubular members.
The coupler may contain more than two tubular members.
The ends of the tubular members to be joined together must reside within the coupler, but they do not have to be physically touching. In one embodiment, the ends of the tubular members are in physical contact touching with nothing else between them. In another embodiment, the ends are close to each other, being separated by less than about 5 millimeters, more preferably less than 3 millimeters. In another embodiment, the ends are separated by a more substantial distance, between about 0.5 and 2 inches. In another embodiment, there is a material located between the ends of the tubular members, such as formed during butt fusion, adhesives, gaskets, or any other suitable material.
From the foregoing detailed description, it will be apparent to those of ordinary skill in the art that a method and apparatus (system) for repair polyolefin structures such as PE or PP pipes as well as non-tubular structures, such as holding tanks and the like, has been disclosed. Although specific implementation details have been provided herein, this has been done solely for the purposes of illustrating generally the scope of the invention, which is defined in the claims which follow. It is to be understood that various substitutions, alterations, and/or modifications may be made to the disclosed embodiment without departing from the actual scope of the invention.
This application is a Continuation-in-part of co-pending U.S. application Ser. No. 14/668,096, entitled, “Method and Apparatus for Repair of Polyolefin Pipes and Structures” filed on Mar. 25, 2015, which is herein incorporated by reference in its entirety.
| Number | Date | Country | |
|---|---|---|---|
| Parent | 14668096 | Mar 2015 | US |
| Child | 15078352 | US |
