Materials Performance

JUN 2019

Materials Performance is the world's most widely circulated magazine dedicated to corrosion prevention and control. MP provides information about the latest corrosion control technologies and practical applications for every industry and environment.

Issue link: https://mp.epubxp.com/i/1121314

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40 JUNE 2019 W W W.MATERIALSPERFORMANCE.COM COATINGS & LININGS ESSENTIALS Continued f rom page 39 Previous Problems Historically, having pipeline risers pass through the splash zone inside I-tubes or pull-tubes provides some protection from the surrounding environment, explains Kirk Francis, regional director of the specialist provider. However, this also creates a situation where the inspection and repair of coatings and sheaths are not possible with the asset remaining in service. And when a riser is pulled into the platform through a pull- tube, the coating can be scraped and dam- aged, with no method for repair. According to Francis, the gels solve the problem of not being able to inspect or repair coating or sheath damage in these situations by removing splash zone considerations. e thixotropic gel is installed inside the tube or other structure to eliminate the cor- rosive air-water interface. is prevents the corrosion of CS pipeline risers or other struc- tures inside the tube, where coating repair and clamps cannot be performed due to lack of access, and where cathodic protection is not very effective, the company says. How the System Works Since the gels are non-aqueous and den- sity tuned to be slightly lighter than sea - water, it sits on top of the seawater and displaces it out of the tube, thereby replac- ing the air-water interface. e product then increases in viscosity and stays static within the tube, despite external waves and platform motions. e gel solution has been designed to be com- patible with steels and polymer materials by coating them and preventing further corrosion. A biocide in the form of tetrakis- hydroxymethyl phosphonium sulfate (THPS) can be added to the mixture for extra protection against MIC, Francis notes. e gel can be installed quickly and requires no hot work, divers, or other safety- critical tasks, thus allowing production to continue during installation. According to the company, it is relatively low cost when compared to existing inspection and repair tools. Further, it does not face the issues associated with lack of access inside a tube. is mitigates the potential problem of not being able to inspect in the region and also

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