Internal repair

A standard metal staircase and railing skirts the outer edge of the tank providing access to the tank roof. A manhole in the tank roof provides access for internal repairs. Discrete inlet and outlet lines are required to feed into the base of the tank. A pressure relief valve is... 

From the time of the introduction of the first adhesive used in an internal application, fibrin sealant, some clinicians have been seeking adhesive solutions to problems in the internal repair of the body, aiming to achieve excellent performance without the problems related to the use of the traditional mechanical means of repair such as localized fixation and the need for removal. Chemists and biologists have been keen to support them in this quest and have produced a wide range of different materials with the abihty to bond one or more tissue types. Initial experimentation is performed on ex vivo tissue and many materials show some promise in that environment. The ability to bond is, naturally, essential, but is not the only requirement, and... 

This chapter will discuss the history of the use of fiber-reinforced polymer (FRP) composites for internal repair of concrete pipelines, with a focus on the design, materials, installation, and quality control for this trenchless pipeline repair and upgrade method. 

Pipe repair options include (1) external repairs, such as circumferential posttensioning, replacement, external steel or CFRP bands, or encasement of the distressed pipe, or (2) internal repairs, such as installing a steel liner or slip-lining with fiberglass or steel pipes, or lining with hand lay-up CFRP. Selecting the best option depends on access, acceptable duration of construction, impact on operation, the expected cost of repair, and reliability of the repaired pipeline. 

There is a wide variety of reinforcing fabrics available in other industries however, for internal repair of pipelines, best practices include only the use of unidirectional carbon fiber fabric as the structural reinforcement. In order to resist all of the design loads acting on the pipeline, separate sheets of epoxy-saturated carbon fiber—reinforcing fabric are applied inside the pipeline with the direction of the fibers oriented in either the longitudinal or the circumferential direction to provide the necessary strength. 

This section provides further information on research, publications, and current developments related to PCCP and the use of CFRP lining systems for internal repair of concrete pressure pipes. 

However, most internal repair methods are used for low operating pressure pipelines and only to restore leak tightness (Toutanji and Dempsey, 2001). Also, these internal repair systems are considered to cause reductions in the inside diameter of pipelines that may hinder the ability to clean and inspect them using traditional tools. Thus, the use of composite materials for internal repair of pipes presents a number of difficulties that have yet to be fully explored. 

A limited number of stodies have been conducted on the internal repair of steel pipelines using composite material systems. As a consequence, only a few industries have used composite technologies for internal repair. In their report, Bruce et al. (2006) indicated that internal repair would have the best economics for underwater repair locations as it reduces out-of-service time and does not require divers and habitats. Such economics arise because the majority of the gas transmission line companies in the United States consider the ability of the pipeline to remain in service during internal repair to be very important. Moreover, they would considCT internal repair, even if the pipeline needs to be out of service (no flow), only if the pipeline remains pressurised and the line can still be inspected by a pipe inspection gauge after repair. However, these companies have indicated that they would consider performing a repair from inside the pipe once a proven and accepted internal repair system becomes available. Thus, the selection of the most appropriate technique of renovation, particularly on the internal repair of high-pressure and deep water pipeline applications, is a critical and ongoing issue. 

Axisymmetric corrosion defect Internal repair liner... 

Classifications of internal repair systems for steel pipelines... 

Cured-in-place A bonded internal repair system using a thin and flexible reinforced textile liner with the outermost layer coated with polyethylene and the inside diameter saturated with liquid thermosetting resin. The liner is usually installed by using water pressure to propel the liner through the pipe and turn it inside out so that the saturated resin side is pressed tightly against the host pipe section to be repaired (Rusch, 2004). 

Around 24 internal repair technologies were reviewed and represented in symbolic form, from 1 to 24. Performance measures, such as maximum allowable working pressure (MAWP) and maximum service temperature, of the various internal repair technology products are identified and plotted in Figures 13.5 and 13.6, respectively. 

Analytical methods are important for internal composite repair systems to ensure that damaged pipelines are properly analysed to evaluate the system against performance measures. Existing methods specifically focus on external repairs of pipelines with internal repairs still unexamined, even though the concept could potentially be applied to internal repairs. Therefore, the concepts and approaches that could be adopted for analysing unbonded and bonded repairs are considered below. 

Studies on internal repair of steel pipe rehabilitations... 

There are currently limited studies eondueted on the internal repair of steel pipelines using eomposite material systems. Similarly, there is a dearth of printed material on the usage and results from sueh repair appheations. Consequendy, there are only a few industries that have used eomposite teehnologies for internal repair. 

Internal repair systems using earbon and glass fibre (GF) composites were reviewed and evaluated by Bmee et al. (2006). Carbon fibre (CF) liner repair was seen as the more promising proeess, having better strength and stiffness characteristics than GF liners. However, the developed and investigated CF liner systems were patch repair only (sectional liners) and bonded to the steel pipelines. The details of these tests are discussed in the following sections. 

Carbon fibre has a modulus of elastieity almost similar to that of steel, thus has greater potential for internal repair of steel pipelines. Bruee et al. (2006) tested a section of 508-mm diameter and 6.35-mm-thick API 5L X52 pipe with a simulated corrosion defect. A defect was introduced to the pipe to represent a 25% reduetion in burst strength. The CF fabric used for the internal repair had a modulus of 241 GPa. 

This chapter reviewed the available literature and teehnologies applieable to the internal repair of corroded steel pipelines using FRP eomposite materials. Rigid bonded,... 

Some novel analytical methods that can be used to effectively design composite materials for internal repair were presented. Finally, available experimental studies conducted on internal FRP repair rehabilitation systems for steel pipe were discussed, demonstrating the high potential of composite materials for restoring the pressure capability of damaged pipelines. 

Bmce, B., Boring, M., Porter, N., Ritter, G., Harwig, D., Harris, I., Dierksheide, J., Mohr, B., Lozev, M., Gordon, R., Neary, C., Sullivan, M., 2006. Internal Repair of Pipelines Final Technical Report. EWI Project No. 46211GTH. Edison Welding Instimte, Columbus, Ohio, p. 202. 

Rusch, D.W., 2004. Internal repair of pipeline leaks using pressure-activated sealants. In Proceedings of the Society of Petroleum Engineer (SPE) Eastern Regional Meeting, West Virginia, 10 pp. 

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