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MC _ CP Rev.0.pdf
The document is a calculation report for a cathodic protection system for a 12" pipeline. It includes: - Design of a cathodic protection system using vertical magnesium galvanic anodes. - Calculations to determine coating damage, surface area to protect, current requirements, anode size and quantity needed. - Recommendation to install seven anode beds along the pipeline to provide protection, with details on anode type, size, installation and connection to the pipeline.
MC _ CP Rev.0.pdf
- 1. REV. 0 12” LINEEXTENSION ENGINEERING DESIGN CALCULATION REPORT OF CATHODIC PROTECTION SYSTEM 11-04-2019 0 SENT FOR APPROVAL C. Vázquez P. Márquez/ M. Guzmán R. Balderaz DATE REV. N° REASON FOR REVISION PREPARED CHECKED APPD. APPD. DOCUMENT NUMBER : CMP-LE-001 JOB NUMBER:
- 2. CALCULATION REPORT OF CATHODICPROTECTION SYSTEM Sideline Testing LCC DATE: 11/04/2019 PAGE: 2 of 12 REV. 0 Disclaimer While all efforts have been made to exercise due care and caution, Sideline Testing LLC cannot assume any liability for damage, injury (personnel or plant), leakage, loss of containment, environmental damage, remediation or the like associated with the subject pipeline. It is understood by all parties that the measurement techniques used and discussed in this report are non-invasive, and as such never made actual physical damage with the subject pipeline. As a result, the data provided may not be indicative of actual pipeline condition and are deductive in nature. All recommendations are based upon similar experience, standard industry methods and best engineering practice.
- 3. CALCULATION REPORT OF CATHODICPROTECTION SYSTEM Sideline Testing LCC DATE: 11/04/2019 PAGE: 3 of 12 REV. 0 CONTENTS LIST OF FIGURES.........................................................................................................4 LIST OF TABLES ..........................................................................................................4 1. OBJECTIVE............................................................................................................5 2. SCOPE OF WORK .................................................................................................5 3. ENGINEERING AND CONSTRUCTION PROJECT OF THE CATHODIC PROTECTION SYSTEM ................................................................................................5 4. REFERENCE DOCUMENTS................................................................................10 5 CONCLUSIONS AND RECOMENDATIONS........................................................10
- 4. CALCULATION REPORT OF CATHODICPROTECTION SYSTEM Sideline Testing LCC DATE: 11/04/2019 PAGE: 4 of 12 REV. 0 LIST OF FIGURES Figure 1. Location of anodic beds along the new and existing pipeline................ 11 Figure 2. Typical multiple galvanic anode installation........................................... 12 LIST OF TABLES Table 1. General information of the pipeline. .......................................................... 6 Table 2. Soil resistivity vs. Degree of Corrosivity .................................................... 7 Table 3. Anode properties....................................................................................... 7
- 5. CALCULATION REPORT OF CATHODICPROTECTION SYSTEM Sideline Testing LCC DATE: 11/04/2019 PAGE: 5 of 12 REV. 0 1. OBJECTIVE To develop a basic detailed engineering based on instructions and standards that integrates the technical support for the design and installation of the cathodic protection system for the project 12 "Line Extension Engineering Design. 2. SCOPE OF WORK Design a cathodic protection system by vertical magnesium galvanic anodes. Sheet of calculations. Elaboration of drawing with specifications for the installation of the cathodic protection system including Bill of Materials. 3. ENGINEERING AND CONSTRUCTION PROJECT OF THE CATHODIC PROTECTION SYSTEM 3.1 GENERAL CONSIDERATIONS The type of cathodic protection system was considered by Galvanic Anodes. Once the cathodic protection system was installed the minimum pipeline potential shall be -0.85 volts with referenced to a saturated copper/copper sulfate electrode. The cathodic protection system is designed for 30 years of life. A 0.9% coating damage was considered to determinate the total external surface area of the pipeline to be protected. It was determined based on the type of coating and the design life of the system. The soil resistivity considered was 500 ohm-cm, along the right of way of the pipeline. The soil resistivity was considered very corrosive in order to design in a conservatively way.
- 6. CALCULATION REPORT OF CATHODICPROTECTION SYSTEM Sideline Testing LCC DATE: 11/04/2019 PAGE: 6 of 12 REV. 0 Table 1. General information of the pipeline. Pipeline ID: 12” LINE EXTENSION ENGINEERING DESIGN Company: Laredo ENERGY Diameter: 12 inches Thickness: 0.375 inches Length: 1.545 miles Type of Coating: 3 layer polyethylene 3.2 OBJECTIVES Determine the total external surface area to protect. Determine the current requirement for an adequate cathodic protection. Select the type and size of the galvanic anodes. Calculate the quantity of galvanic anodes required. Calculate the anode bed to the earth resistance. Calculate the current output from the anode. Determinate the anode life. Distribute in a uniform way the anodes along the ROW of the pipeline. 3.3 DESIGN BASIS Cathodic protection has been used for the effective control of external corrosion of submerged or buried metallic structures. For galvanic anode CP systems, the anode of the electrochemical cell is a casting of an electrochemically active alloy (normally aluminum, zinc or magnesium based). This anode is also the current source for the CP system and will be consumed. Accordingly, it is often referred to as a “sacrificial anode”, as alternative to the term “galvanic anode”. The galvanic anodes protection consists in electrically joining the metal structure that it is about protecting with a more electronegative metal than the steel buried in the same electrolyte. The existence of the electrolyte is completely essential, which completes the system for the process.
- 7. CALCULATION REPORT OF CATHODICPROTECTION SYSTEM Sideline Testing LCC DATE: 11/04/2019 PAGE: 7 of 12 REV. 0 3.4 SOIL RESISTIVITY The soil considered for the design of the cathodic protection system was 500 ohm- cm, considering a very corrosive soil along the ROW of the pipeline, according the Table 2. Table 2. Soil resistivity vs. Degree of Corrosivity Soil Resistivity Degree of corrosivity 0-500 Very Corrosive 500-1000 Corrosive 1,000-2,000 Moderately corrosive 2,000-10,000 Mildly corrosive Above 10,000 Negligible 3.5 CALCULATIONS - CURRENT OUTPUT FROM THE ANODE Current Output for One Anode I = Current output of one anode in amps 0.363 Ec = Cathode potential in volts (potential to which the pipe is to be polarized) -0.85 Ea = Anode potential in volts -1.55 Ra = Groundbed resistance in ohms 1.93 Table 3. Anode properties H-1 Alloy Cast Magnesium Anode Current density 3.25 mA/ft² Dimension 5 x 5 x 21 inches Theoretical Amp Year per Pound 0.116 Amp-yr/lb Potential with ref to CuSO4 -1.55 volts Electrochemical capacity of Anode 500 Amp-hour/lb Current Efficiency (%) 50 Weight of anode 32 lbs Utilization 0.85
- 8. CALCULATION REPORT OF CATHODICPROTECTION SYSTEM Sideline Testing LCC DATE: 11/04/2019 PAGE: 8 of 12 REV. 0 - ANODE LIFE ANODE LIFE V = Life in years. 4.34 C = Theoretical Amp Year per Pound 0.116 P = Anode weight in lbs 32 R = Efficiency 0.50 U = Utilization 0.85 I = Current output of the anode in amps 0.363 - SURFACE AREA TO PROTECT TOTAL EXTERNAL SURFACE TO PROTECT AB = surface area in sq. ft. 245.07 f = coating damage factor 0.009 π = 3.1416 3.1416 D = Diameter in ft. 1.0625 L = lenght in ft. 8157.6 - CURRENT REQUIREMENT CURRENT REQUIREMENT I = current requirement in amps 0.80 AB = surface area in sq.ft. 245.07 ID = current density in mA/sq.ft. 3.25
- 9. CALCULATION REPORT OF CATHODICPROTECTION SYSTEM Sideline Testing LCC DATE: 11/04/2019 PAGE: 9 of 12 REV. 0 - REQUIRED ANODIC MASS MASA ANÓDICA REQUERIDA W = total wegiht of required anodic mass in lbs 454 I = current requirement in amps 0.80 DR = Anode consumption lbs/yer 19 DL = CP system design life in years) 30 - NUMBER OF REQUIRED ANODES NUMBER OF REQUIRED ANODES N = Number of required anodes 14 W = total weight of required anodic mass in lbs 454 WA = weight of one anode in lbs 32 - GROUND BED RESISTANCE Ground bed Resistance for Multiple Vertical Anodes in Parallel (Sunde’sFormula) R = resistance in ohms 1.93 ρ = soil resitivity in ohm-cm 500 L = anode lenght in feet 1.75 d = anode diameter in feet 0.417 S = anode spacing in feet 13 N = number of anodes 2 *ln is the natural logarithm function
- 10. CALCULATION REPORT OF CATHODICPROTECTION SYSTEM Sideline Testing LCC DATE: 11/04/2019 PAGE: 10 of 12 REV. 0 4. REFERENCE DOCUMENTS The documents listed below are an integral part of the calculation report. Control of Pipeline Corrosion, A.W. Peabody Edited by R. L. Binchetti. Cathodic Protection Survey Procedures, Second Edition, W. Brian Holtsbaum. CP-1 Cathodic Protection Tester Course manual, NACE International. CP-2 Cathodic Protection Technician Course manual, NACE International. CP-3 Cathodic Protection Technologist Course manual, NACE International. APPLICABLE CODES & STANDARDS • NACE SP 0169 Control of External Corrosion on Underground or Submerged Metallic Piping Systems • ISO 15589-1:2015. Petroleum, petrochemical and natural gas industries – Cathodic protection of pipeline systems - Part 1: On-land pipelines. 5. CONCLUSIONS AND RECOMENDATIONS It is recommended to install seven anodic beds along the right of way uniformly distributed, located as follows in progressive mileage, see Figure 1 for more details: - Bed 1, mile 0.85, two vertical galvanic anodes. The progressive mileage is considered from the zero in the interconnection point with the new pipeline to the end of the existing pipeline. - Bed 2, mile 0.59, two vertical galvanic anodes. The progressive mileage is from the zero in the interconnection point with the new pipeline to the end of the existing pipeline. - Bed 3, mile 0.33, two vertical galvanic anodes. The progressive mileage is from the zero in the interconnection point with the new pipeline to the end of the existing pipeline. - Bed 4, mile 0.08, two vertical galvanic anodes. The progressive mileage is from the zero in the interconnection point with the new pipeline to the end of the existing pipeline.
- 11. CALCULATION REPORT OF CATHODICPROTECTION SYSTEM Sideline Testing LCC DATE: 11/04/2019 PAGE: 11 of 12 REV. 0 - Bed 5, mile 0.176, two vertical galvanic anodes. The progressive mileage is from the zero in the interconnection point with the existing pipeline to the end of the new pipeline. - Bed 6, mile 0.43, two vertical galvanic anodes. The progressive mileage is from the zero in the interconnection point with the existing pipeline to the end of the new pipeline. - Bed 7, mile 0.68, two vertical galvanic anodes. The progressive mileage is from the zero in the interconnection point with the existing pipeline to the end of the new pipeline. Figure 1. Location of anodic beds along the new and existing pipeline. The anodes should be H-1 Alloy Cast Magnesium Anodes, 32 lbs. in weight and will be buried at a depth equal to or greater than the pipeline depth and should be separated at a minimum distance of 10 feet from the axis of the pipeline, the spacing between anodes should be 10 feet at least. The connection of the HMWPE 12 AWG Cathodic protection cable from the anode to the pipeline must be joined by exothermic welding and shall be properly insulated. A test station should be placed in each anodic bed for potential reading in order to determine effectiveness of the cathodic protection system.
- 12. CALCULATION REPORT OF CATHODICPROTECTION SYSTEM Sideline Testing LCC DATE: 11/04/2019 PAGE: 12 of 12 REV. 0 Figure 2. Typical multiple galvanic anode installation.