In the upstream production systems,the external corrosion management typically does not affect thedefinition of the whole gathering network system design.However,its role is crucial for the integrity ofany steel structure.The external corrosion is generally managed with external coatings or cathodic protection systemsdesigned to provide a durable protection against corrosive environments (either onshore or offshore).Typical external coating materials are polypropylene,polyethylene (in case of polyolefin coating),fusionbounded epoxy (FBE) or,in specific applications,thermal sprayed aluminium (TSA).In High Pressure and High Temperature (HP/HT) reservoir applications,usually located in deepwatersoffshore where the ambient temperatures are low (i.e.high temperature gradient between inside the pipelinesand external environment),the selection of a specific external coating material might have significant impacton the design specification of the installed hardware,with special focus on the pipelines.In fact,dependingon different physical properties of the external coating technologies,those may introduce stronger or weakerinsulating capabilities and will modify the pipelines U Value,which describes the capacity of the pipelinesto exchange heat with the external environment (and consequently the design specification of the productionnetwork).A Case Study is here presented where impacts on the pipeline design specifications based on the selectionof different external coating technologies have been described.In particular,it is here shown how theapplication of coating materials with lower insulating performance,e.g FBE coating,can increase the heatexchange between the hot production fluid and the cold external environment,leading to faster cooldownof production fluid.In this case,reduction in operating fluid temperature has been used to prevent internal corrosion issues(generally linked to top of the line corrosion),however it may also be used as mitigation of HP/HT relatedissues,e.g.lateral buckling.Main pros and cons of FBE applied as a standalone external anticorrosioncoating have been described in this paper.
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