Composite Sleeves / Composite Wraps
Composite sleeves or full composite wraps are the latest innovation in pipeline defect repair where leakage or spillage has not started.
They are well suited for repairing contoured pipelines and sections of pipelines where fittings are installed, such as small take-off points or metering points.
They are capable of restoring damaged pipelines to their original Maximum Allowable Operating Pressure (MAOP), with the added benefit of coating the pipes to protect them from corrosion. Today, commercially available prefabricated sleeves (designed and cured in a factory for rapid installation on site and also wet sleeves that are wrapped and cured on site as needed.
Most popular and CPL approved (Chevron Pipeline Company) composite sleeve is Clock Spring® which are made up of corrosion-resistant high tensile fiberglass material.
However, ASME B31.8 only accepts such repairs in case "proven through reliable engineering tests and analysis." Where possible, composite sleeve wrapping is carried out at one-third of the operating pressure so that sleeve can share hoop stress once the pipe is restored to regular operation.
During application, fiberglass is wrapped around a damaged portion of bare pipe, after cleaning, in layers, and a filler metal is applied in each layer. For dented areas, special hardening filler material (provided by composite sleeve manufacturer) is used before the application of sleeve wrapping. Pipeline pressure should be kept reduced until the completion of sleeve installation and curing time.
Installation of composite sleeves is never recommended for damaged pipes where cracks have developed. Installation of composite sleeves should be performed by personnel trained and certified by qualified instructors, preferably under the guidance of the composite sleeve manufacturer. When these conditions are met, a composite sleeve offers damage repair for..
Important: Some pipeline experts/companies still doubt the long-term integrity of of composite sleeves because of the aging of the sleeve material.