Cathodic Protection and Field Surveys of Underground Pipelines
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The document discusses corrosion control techniques for underground pipelines, including coatings, cathodic protection, and chemical inhibitors. It outlines the objectives of minimizing corrosion to increase pipeline lifespan and safety. Key techniques are summarized, such as using coatings as a barrier between the pipeline and environment, cathodic protection methods like galvanic anodes and impressed current, and chemical inhibitors. Field surveys like pipe-to-soil potential and close interval potential surveys are described. Experimental work involved performing these surveys on various pipelines and coating inspection. The conclusion emphasizes the importance of corrosion control for oil/gas pipelines and following standards like NACE for cathodic protection.
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Cathodic Protection and Field Surveys of Underground Pipelines
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- 2. PROJECT TITTLE Corrosion Control/ Cathodic Protection, and Field Surveys of underground pipeline network DAWOOD UNIVERSITY OF ENGINEERING & TECHNOLOGY KARACHI 2
- 3. Group Members Dilnawaz D-12-MME-373 Shahnawaz D-12-MME-394 Waqas Junaid D-12-MME-375 Abdul Baseer D-12-MME-379 Israr Ahmed D-12-MME-363 Internal Supervisor METALLURGY & MATERIALS ENGINEERING DEPARTMENT Dr Khursheed Mehmood 3
- 4. CONTENTS Objective Introduction To Corrosion Corrosion Control Techniques Coatings Cathodic Protection Chemical Inhibitors Field Surveys Experimental Work And Results 4
- 5. OBJECTIVE To minimize the corrosion rate in oil & gas sectors To save worlds metal Avoiding hazardous conditions (hydrogen embritlement , blasting of pipes) For increasing life of oil/Gas pipeline To provide high quality of product To run plants good and safe manner 5
- 8. S:No Environment Corrosivity 01 Sea water High 02 Fresh water Low 03 H2SO4 Very high 04 Petroleum & gasses High ENVIRONMENTS AND CORROSIVITY 8
- 10. FORMS OF CORROSION Uniform corrosion Crevice corrosion Galvanic corrosion attack Pitting corrosion 10
- 11. Intergranular corrosion attack Stress corrosion cracking Erosion corrosion 11
- 13. CORROSION CONTROLLING METHODS 1. Coating 2. Cathodic Protection • Cathodic Protection with Galvanic Anodes • Impressed Current Cathodic Protection 3. Chemical Corrosion Inhibitors 13
- 14. COATING FOR PIPELINE Coating is used to protect the pipeline structure and acts as insulated barrier between the environments and the pipelin. Coating is also known as first line of action. It is the best way to protect the metal pipeline from corrosion. It prevents the metal pipeline in direct contact with the electrolyte (soil & water). Coating can also be used for any environment. 14
- 15. TYPES OF COATING 1. ENAMEL COATING 2. TAPE COATING 3. POLYETHYLENE C OATING 4. COLD APPLIED LIQUID COATING 15
- 18. COLD APPLIED LIQUID COATING 18
- 20. CATHODIC PROTECTION FOR PIPELINE Cathodic protection is an electrochemical process of controlling corrosion activities of underground or submerged metallic structures. The concept of cathodic protection involves reducing the potential differences between the local anodic and cathodic sites. Rate of corrosion could be reduced if every bit of exposed metal on the surface of a pipeline could be made to collect current 20
- 21. TYPES OF CATHODIC PROTECTION 1. CATHODIC PROTECTION WITH GALVANICANODES 2. IMPRESSED CURRENT CATHODIC PROTECTION 21
- 22. CATHODIC PROTECTION WITH GALVANIC ANODES 22
- 24. NACE CRITERI FOR CATHODIC PROTECTION NACE standard RP0169 “control of external corrosion on underground or submerged metallic piping system.” There are three criteria defined in the NACE RP0169 for steel and cast iron including ductile iron are: •A negative (cathodic) potential of at least 850 Mv •A negative polarized potential of at least 850 mV •A minimum of 100 mV of cathodic polarization 24
- 27. PIPE TO SOIL POTENTIAL (PSP) DIRECT CURRENT VOLTAGE GRADIENT (DCVG) CLOSE INTERVAL POTENTIAL SURVEY(CIPS) PIPELINE CURRENT MAPPER (PCM) FIELD SURVEYS 27
- 29. DIRECT CURRENT VOLTAGE GRADIENT (DCVG) 29
- 32. Our project experimental work totally based on the field surveys and collecting result of different pipeline structures. We spent 15 days and did some survey at MPL-325, MPL-316, MPL-330, and FOJI FERTILIZER BIN QASIM LIMITED post line. We had two days on coating of indus left bank pipeline 16” dia. We did following surveys and test there: •Pipe-to-soil potential •Close interval potential Survey •Holiday inspection of new coated pipeline EXPERIMENTAL WORK 32
- 33. Check Test point Locations Reading Current drain MPL-325 1.28 No current drain MPL-316 1.45 No current drain MPL-330 0.87 Current drain found FFBQL 1.25 No current drain PIPE-TO-SOIL POTENTIAL 33
- 34. KMP-341 U/S graph CLOSE INTERVAL POTENTIAL SURVEY 34
- 35. KMP-341.5 U/S 35
- 36. HOLIDAY INSPECTION Holiday inspection is used to detect coating defect and holidays on new coated pipeline before it buried and old pipeline that has some coating damages. We inspected this method on indus left bank pipeline 16” dia, that was dug for new coating about 1Km. Coal-tar coating was applied on pipeline. We inspected that coated pipeline with holiday detector, and three section were not properly coated. All the damaged sections recoated again and inspected to witness that no holidays on pipeline. 36
- 37. CONCLUSION Corrosion is most common problem for any metallic structure that are used in different operating conditions and environments. It is very critical for oil and gas sector pipeline and underground storage tanks. Cathodic protection has variety of application over this underground pipeline and storage tanks. The cathodic protection designed and installed according to the NACE standards. NACE standards for external metallic cathodic protection is RPO 169 that is the potentials must be maintained - 850 mV 37
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