North American Oil & Gas Pipelines

SEP 2018

North American Oil & Gas Pipelines covers the news shaping the business of oil and gas pipeline construction and maintenance in North America, including pipeline installation methods, integrity management innovations and managerial strategies.

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34 North American Oil & Gas Pipelines | SEPTEMBER 2 018 By Casey Whalen C omposite repair products used in oil and gas pipeline reha- bilitation and restoration applications have been available for close to 30 years. In that time, multiple misconceptions have evolved regarding these products, their principles and their performance. Myth: "Any off-the-shelf product can address my simple repair" There are plenty of manufacturers that would have operators believe their products are adequately manufactured to handle any repair based on their one-size-fits-all construction. In reality, these types of products can provide a good repair solution only in the right conditions, but even then, that doesn't necessarily make it right or the best option. There are many variables when considering a composite repair, including operating pressures and temperatures, defect type and severity, pipe geometry and external or internal chemical presence. Considering all these variables, it is near impos- sible for a single, ready-made composite to work well in every situ- ation. A wrinkle bend case study from Ringgold, Louisiana, shows how a customized repair was necessary over a pre-designed repair. A 24-in. OD horizontal pipeline in Ringgold needed a repair for six wrinkle bends at a crossing about 26 to 31.5 in. apart. With no visible corrosion, the distance from the center of the first wrinkle bend to the sixth wrinkle bend was 12.2 ft. Milliken Infrastructure Solutions (MIS) engineers designed a 20- year design life repair, using 20 layers of the Atlas wrap system using the spiral method for 16 lf to restore the structural integrity of the pipeline back to pristine conditions. Wrinkle bends provide local- ized stress increases that can dramatically reduce the life of a pipe undergoing fatigue. The Atlas system was designed to locally reduce the stress in the buckled areas increasing fatigue life closer to that of the pristine pipe. The severity of the repair as well as operating conditions play a large part in the long-term effectiveness of the pipeline system and any composite repair needs to address these details to ensure longevity can be achieved. The repair was completed in 13 hours by three MIS technicians and three contracted personnel. The repair area was grit blasted and wiped clean with acetone, then EP420 was applied as filler material for the load transfer at the wrinkle bends. Next, PPR epoxy coating was applied to the entire repair zone followed by a layer of fiberglass with ILI markers on both ends of the repair. The composite wrap system was applied, followed by constrictor wrap, perforation and then allowing adequate time to cure. After curing, the constrictor wrap was removed, and the team applied a topcoat with additional PPR epoxy coating. "Pre-designed," ready-made repair products should only be used to address very specific situations. These situations and limitations should be clearly and plainly understood. However, keep in mind that the prevailing ASME PCC-2 and ISO 24817 standards state that each repair should be properly designed in accordance with the guidelines. Finding a product that is engineered to the exact specs of a given scenario will not only offer the optimum design required to provide a sufficient repair, but it can also reduce costs. Addition- ally, there are many other conditions, such as bending or combined loading, that the repair must address. This is more likely to be done if the repair is custom designed by a knowledgeable engineering team versus assuming an off-the-shelf product has pre-considered every specific loading condition. Myth: "Composite products provide only a temporary repair solution" The largest issues with this misconception is lack of definition when it comes to the words "temporary" and "permanent." They tend to mean something different to each operator, manufacturer and auditor. With regards to composite repairs designed for one sce- nario or the other, a general definition may be given as: Temporary repair: This repair will be installed for a specified, usu- ally short, amount of time with specialized scheduled inspections or a planned service removal. Permanent repair: This repair will be installed without require- ments for specialized scheduled inspections other than routine scheduled inspections for the entire pipe. In either case, a "permanent" repair is only viable for a com- posite repair system if the defect itself has been addressed and no further damage to the pipe or composite repair is antici- Fixing Myths Dispelling Composite Repair Misconceptions Through Case Studies

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