Optimization of Eregli high pressure natural gas pipe line cathodic protection system by using different anode materials

OPTIMIZATION OF EREGLI HIGH PRESSURE NATURAL GAS PIPELINE CATHODIC PROTECTION SYSTEM BY USING DIFFERENTANODE MATERIALS(M.Sc. Thesis)Fatih Mehmet BOLUKGAZİ UNIVERSITYINSTITUTE OF SCIENCE AND TECHNOLOGYSeptember 2006ABSTRACTCorrosion is a natural phenomena which can be defined as the deformation of amaterial due to the interaction with its environment. Cathodic protection is oneof the most effective methods to prevent corrosion. Cathodic protection systemdesigns are generally based on the determination of the current required toprotect the targetted structure by changing anode type and configuration.Cathodic protection can also prevent corrosion completely in undergroundnatural gas pipeline systems. In this study, an impressed current cathodicprotection system design was carried out on the Eregli High Pressure NaturalGas Pipeline. In order to design the cathodic protection system, site survey andsoil resistivity measurements along the pipeline were performed. Four types ofanode material (mixed metal oxide coated titanium anode, iron silicone anode,graphite anode and platinum coated titanium anode)were selected for cathodicprotection. These anode materials were compared from the point of mass loss,current efficiency, and the number of anodes required for cathodic protection(with specified dimensions). By analyzing these parameters, most suitable anodematerial was determined for Eregli High Pressure Natural Gas Pipeline.On this study it is determined that, resistivity of all anode beds are between 0,93to 0,99 ohm. So resistivity of anode beds are sufficient. From the point ofnumber of anodes used, highest number of graphite anodes (37) and lowestnumber of iron silicone anodes (31) were determined for the cathodicprotection. It is also required 32 mixed metal oxide coated titanium anodes and33 platinum coated titanium anodes. From the point of anode bed resistivity andthe number of anodes; it is determined that there is no significant differencebetween anode types except graphite anode. In spite of this similarity, it isknown that there is a huge difference in current capacity and mass loss valuesof the anode materials considered in this study. Mixed metal oxide coatedtitanium anode is the highest, on the other hand, mass loss value of the sameanode is the smallest. As a result of this study, it is decided that mixed metaloxide coated titanium anode is the most appropriate one not only due to lowanode number, current capacity and mass loss but also its being adaptable toany kind of environment and its non passivizing character during operation.Science Code : 912Key Words : Corrosion, cathodic protection, anode, metal oxidePage Number : 79Adviser : Dr. N. Alper TAPAN