Materials Performance Supplements

Corrosion Management for Pipeline Integrity 2018

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.

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14 JUNE 2018 W W W.MATERIALSPERFORMANCE.COM CORROSION MANAGEMENT FOR PIPELINE INTEGRIT Y SUPPLEMENT TO MP Field Joint Coatings Lee Wi L son , Corrosion Control and Solutions, Tyne and Wear, United Kingdom Engineering and selecting the most ade- quate and appropriate pipeline coating depends upon a multitude of factors. Care- ful analysis of several critical factors must be considered, such as the pipe diameter, the service pressures or operating tempera- tures of the transport materials, the soil conditions if installing a landline, construc- tion techniques for installation, cathodic protection (CP), and whether impressed current CP or sacrificial CP will be used. These are all factors that will determine the material selection for pipeline protection; and it is important to understand that the critical field joint zone and girth weld will be subjected to precisely the same factors, stresses, and service conditions. What is a Field Joint? The area where two pipe spools or pipe joints are welded together is known as the field joint. This is a significant area because the pipe is welded here and its surface is uncoated. Subsequently, the field joint is exposed to the environment and suscepti- ble to corrosion. Field joints are often con- sidered the weakest point within a pipeline prim ari ly du e to c omp ati bi lity i ssu e s between the factory-applied or mainline coating and the selected material used to protect the field joint. Some of the most important properties that field joint coat- ing systems must provide are: • Long-term corrosion protection and th ermal insul ation p er for - mance • Excellent adhesion to the substrate that is to be protected • Exceptional compatibility with the factory or mainline coating system • The ability to be applied under extreme environmental conditions • E a se of appli cation—to en sure rapid application and reduced field joint cycle times Challenges when engineering the most suitable anticorrosion protection systems for the transport pipeline include cost effectiveness, safety of operators and appli- cators, the proposed lifetime of the struc- ture, local legislation, and coating in con- junction with CP. There are many other factors as well that depend greatly upon the pipe itself. Corrosion is one of the leading causes of failures of subsea and land-based pipeline transportation systems, with both internal and external corrosion recorded as signifi- cant factors in pipeline coating failures. Sig- nificant catastrophic failures recorded in recent history have linked corrosion failure to health, safety, and environmental conse- quences for operators and the public, and fines for negligence have cost hundreds of millions of dollars. The criticality of engi- neering a suitable field joint coating to cope with extreme environmental and service conditions is imperative. Coating a Field Joint In recent years there have been signifi- cant changes to the way field joint coating systems have been engineered. Tradition- ally the field joint coating was often over- looked and protection for this crucial zone was based upon compatibility with the mainline coating, regardless of whether or not the field joint coating requirements were different. Several factors differ between the main- line factory coating and the field joint coat- ing. For example, the mainline coating is often applied in ideal factory conditions using specialized equipment, and time spent on surface preparation and applica- tion is not critical. Since field joint coatings are applied in the field, they are subject to extreme environmental factors with differ- ences in ambient conditions. Historically, the application of field joint coating sys- tems has been rushed to adhere to critical cycle and production times, which has sub- sequently led to quality issues and prema- ture failures. Simply put, the field joint coating system must be integrated into the pipeline construction conditions. Pipeline Protection Articles A field joint coating system must be integrated into a pipeline's construction conditions.

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