Abstract
Cathodic protection (CP) has been used as a primary method in the control of corrosion, therefore it is regarded as the most effective way for protecting buried pipelines. However, it is difficult to apply CP to a pipeline for district heating distribution systems, because the pipeline has thermally insulated coatings which could disturb the CP. Theoretical calculation and field tests alone are not enough for a reliable CP design, and therefore additional CP design methods such as computational analysis should be used. In this study, the CP design for pre-insulated pipelines is tested considering several environmental factors, such as temperature and coating defect ratio. Additionally, computational analysis is performed to verify and optimize the CP design. The simulation results based on theoretical methods alone failed to satisfy the CP criteria. Then, a re-design is conducted considering the IR drop. Consequently, all of the simulation results of defective pipelines satisfied the CP criteria after adding the proper CP current.
Highlights
IntroductionIn district heating (DH) systems, heated water is distributed through a double-pipe network and transferred to buildings for use in space heating, hot water generation, and process heating [1]
In district heating (DH) systems, heated water is distributed through a double-pipe network and transferred to buildings for use in space heating, hot water generation, and process heating [1].DH systems have three main elements: the heat source, the distribution system, and the customer interface
The high-density polyethylene (HDPE) is susceptible to unpredictable mechanical damage, and the polyurethane foam (PUR) can be vanished by heat, humidity, and oxygen during its long operational life [4,5]
Summary
In district heating (DH) systems, heated water is distributed through a double-pipe network and transferred to buildings for use in space heating, hot water generation, and process heating [1]. The impressed current CP (ICCP) system has a power supply (rectifier) that generates larger potential differences between the anode and the structure [9] For this reason, ICCP is applied to many industrial pipelines. The immersed PUR layer can deteriorateduring and long operating periods, causing exposure of theexposure bare carbon to thecarbon corrosive environment For this vanish during long operating periods, causing of steel the bare steel to the corrosive reason, it is For important to apply to operating pipelines external coatingwith defects, as a precaution environment. Is alsothe appropriate protecting current required to reach therequired external to surface theexternal pipelinesurface with proper difficult to verify the appropriate protecting current reachofthe of theCP potential For this reason, additional design methods, such as computational analysis, pipeline with proper CP potential. A computational analysis was performed verify and optimize design pre-insulated pipelines.
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