INSTITUTE OF INTEGRATED ELECTRICAL ENGINEERS OF THE PHILIPPINES, INC. (IIEE-ERCSA) First IIEE Accredited Foreign Chapter (Charter

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1 INSTITUTE OF INTEGRATED ELECTRICAL ENGINEERS OF THE PHILIPPINES, INC. () First IIEE Accredited Foreign Chapter (Charter No. 62) Most Outstanding Chapter Overseas for the year 1998, 1999, 2000, 2002, 2003 & 2005 Foreign Chapter Excellence Bronze Awardee 2013 Foreign Chapter Excellence Silver Awardee

2 Buried Pipeline Production Pipeline : A pipeline transporting oil, gas or water to or from a well. These include flow lines, test lines, water injection lines and trunk lines. Flow lines-a pipeline connected to a well Test lines-a pipeline that is used for testing an individual well or group of wells. Trunk lines-a pipeline designed to distribute or gather product from two or more wells, typically connecting flow lines or injection lines to the associated GOSP or WIP. 2

3 Buried Pipeline Cross Country Pipeline: A pipeline between; two plants areas, another cross-country pipeline and a plant area, or between two cross-country pipeline. Transmission Pipeline: A cross country pipeline transporting product between GOSPs, WIPs or other process facilities Utility Pipeline: A pipeline designed to deliver an end use service product (typically water, gas or air) 3

4 Deep Anode Bed: Anode or anodes connected to a common CP power supply Installed in a vertical hole (typically 25 cm diameter) with a depth Exceeding 15 m (50ft) Galvanic Anode: Anode fabricated from materials such as aluminum, magnesium or Zinc that are connected directly to the buried structure to provide cathodic protection without the requirement for an external cathodic protection power supply. Galvanic anodes are also referred to as sacrificial anodes Impressed Current Anodes: Anodes fabricated from materials such as High Silicon Cast Iron (HSCI) or Mixed Metal Oxide (MMO) that are immersed or buried and are connected to the positive terminal of a DC power supply to provide cathodic protection current. 4

5 Project : UBTG-1 Pipeline Replacement Project Length : 67 kilometer Diameter of pipe : 56 inches 5

6 Contents What is Cathodic Protection? General Design Requirements CP Performance Criteria CP Material Requirements Installation, Testing and References 6

7 What is Cathodic Protection? Cathodic protection (CP) is a technique used to control the corrosion of a metal surface by making it the cathode of an electrochemical cell. 7

8 A 'Cathode' is a Negatively charged Electrode (or Element) that attracts the Positive (+) ions (Cations) in a Circuit or Chemical reaction. The 'Anode' is the Positively charged Electrode (or Element) that attracts the Negative (-) ions (Anions) in a Circuit or Chemical reaction. Diagram of a copper cathode in a galvanic cell (e.g., a battery). A positive current i flows out of the Cathode. 8

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13 CP Method The simplest method to apply CP is by connecting the metal to be protected with a piece of another more easily corroded "sacrificial metal" to act as the anode of the electrochemical cell. The sacrificial metal then corrodes instead of the protected metal. For structures where passive galvanic CP is not adequate, for example in long pipelines, an external DC electrical power source is used to provide current. 13

14 General Design Requirements Design Considerations Soil Resistivity Survey Results Design Current Density Protection Criteria System Design Life 14

15 Soil resistivity is a function of soil moisture and the concentrations of ionic soluble salts and is considered to be most comprehensive indicator of a soil s corrosivity. Typically, the lower the resistivity, the higher will be the corrosivity as indicated in the following Table Corrosivity ratings based on soil resistivity 15

16 Design Current Density = 0.10 ma/m² 16

17 Design Current Density = 0.10 ma/m² 17

18 Protection Criteria Pipelines: The negative pipe-to-soil ON potential shall be a minimum of 1.2 volts and a maximum of 3.0 volts, with reference to a copper/copper sulfate electrode Pipeline Valves and associated buried piping: The negative pipe-to-soil ON potential shall be a minimum of 1.0 volts and a maximum of 3.0 volts, with reference to a copper/ copper sulfate electrode For all pipelines, cathodic protection must be achieved within 30 days of pipeline burial. If this cannot be met, provide temporary cathodic protection. 18

19 System Design Life The design life of cathodic protection system for pipeline shall be for 20 years. The design life of anodes shall be calculated as per SA-SAES-X-400 paragraph 7.2 Formula: Design Life = Total Anode Weight(Kgs) 20 Anode Cons. Rate x Rect. Rated Current Cap. Where: Total Anode Weight, WA =38.6 Kg x 36 nos. Anode Consumption Rate = 0.45 Kg/A-Y Rated Current Capacity = 150 A Design Life = years Using 36 x TA-4 anodes satisfies the minimum requirement design life of 20 years or more 19

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21 CP Performance Criteria Guidelines & Parameters Surface area to be protected Calculation of Deep Anode Temporary CP System 21

22 Guidelines & Parameter Guideline/Parameter CP system type Anode installation Anode type Anode Weight net weight Anode current capacity Value/ Comment Impressed Current Deep Well Anode Bed High Silicon Cast Iron (TA-4) 38.6 Kg (SAES-X-400) 4.45 A (SAES-X-400) Anode-bed Active length 11,000cm Anode-bed diameter 25cm Nos. of Anodes 36 Anodes Spacing 100cm Anode consumption rate 0.45 Kg/A-Y (SAES-X-400) Anode current density 0.7mA/cm² (SAES-X-400) Life 20 Years (SAES-X-400) Soil Resistivity 1,400 ohm-cm 22

23 Surface Area To Be Protected 23

24 System Design Life The cathodic protection system for pipeline is designed For 20 years. The design life of anodes shall be calculated As per SA-SAES-X-400 paragraph 7.2 Formula: Design Life = Total Anode Weight(Kgs) 20 Anode Cons. Rate x Rect. Rated Current Cap. Where: Total Anode Weight, WA =38.5 Kg x 36 nos. Anode Consumption Rate = 0.45 Kg/A-Y Rated Current Capacity = 150 A Design Life = years Using 36 x TA-4 anodes satisfies the minimum requirement design life of 20 years or more 24

25 Temporary Cathodic Protection System Design Considerations: Soil Resistivity: Assume a value of 3,000 ohm-cm Current Density : As per SA standard SAES-X-400 specifies a current of 0.005mA/m² (Table 2) Protection Criteria: The negative pipe-to-soil ON potential shall be a minimum of -1.0 volts and a maximum of 3.0 volts. Design Life: As per SA standard SAES-X-400 specifies The minimum design life of temporary CP shall be 2 years 25

26 CP Material Requirements ICCP/Transformer Rectifier Anode Junction Boxes Bond Boxes Test Station 26

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37 An air cooled cathodic protection rectifier connected to a pipeline 37

38 An air cooled cathodic protection rectifier connected to a pipeline 38

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40 Junction Box 40

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46 References NACE National Association of Corrosion Engineers SAES-X-400 Cathodic Protection of Buried Pipeline 46

47 INSTITUTE OF INTEGRATED ELECTRICAL ENGINEERS OF THE PHILIPPINES, INC. () First IIEE Accredited Foreign Chapter (Charter No. 62) Most Outstanding Chapter Overseas for the year 1998, 1999, 2000, 2002, 2003 & 2005 Foreign Chapter Excellence Bronze Awardee 2013 Foreign Chapter Excellence Silver Awardee