Paper No Christophe Baeté, CP Manager Elsyca n.v. Vaartdijk 3/603, 3018 Wijgmaal, Belgium

Transcription

1 Paper No CP MANAGEMENT OF MULTIPLE PIPELINE RIGHT-OF-WAYS Len J. Krissa, P.Eng. Engineering Specialist Enbridge Pipelines Inc Jasper Avenue Edmonton, AB T5J 3N7, Canada Jerry DeWitt, Sr. CP Specialist Enbridge Energy Partners 222 US 41 Schererville, IN , USA Christophe Baeté, CP Manager Elsyca n.v. Vaartdijk 3/603, 3018 Wijgmaal, Belgium ABSTRACT The report discusses cathodic protection (CP) experiences on the world s longest, most complex crude oil and liquid hydrocarbon transportation system; having 24,738 kilometers (15,372 miles) of pipeline throughout North America. Since initial construction of the first pipeline in 1949, infrastructure has continually been enhanced and improved to meet the needs of the Company s shippers. The expansion has resulted in areas of the mainline corridor where up to seven (7) parallel pipelines are contained within the same right-of-way (ROW). The evolution of construction materials over the course of the Company s long operating history has contributed to the diversity within the ROW. Early coating systems included asphalt, coal tar epoxy, and mummy-wrap. Polyethylene tape coated pipe was installed in the late 1960 s and 1970 s. Since the 1980 s, the Company has favored high performance coatings such as fusion bonded epoxy, dual layer epoxies, and high performance composite/powder (HPCC/HPPC). Presently, the ROW includes an assortment of pipeline vintages with various diameters and coating types which can consequently result in unbalanced CP levels. This Project includes in-depth research and analysis of various methods, procedures, and materials beneficial in regulating and maintaining appropriate levels of CP in complex multi-pipeline corridors. Associated rectifiers are all furnished with remote monitoring equipment and the majority of test stations have been retrofit with coupons enabling remote surveillance of real time CP/AC potentials and 1

2 corresponding current densities. All Project pipelines are regularly evaluated using inline inspection tools equipped with technologies to identify metal loss, and some of the pipelines have been inspected using inline tools capable of evaluating CP currents flowing in the pipe wall. These data have been consolidated and used to generate a computational model providing a more accurate representation of CP levels on each pipeline within the shared ROW. The purpose of such a model is to refine testing procedures, develop corrective measures and establish new guidelines for optimizing CP operation and effectiveness within ROWs containing multiple pipelines. Rationally managing and harmonizing CP levels within such multifaceted arrangements is necessary to accommodate the pipelines having a high current demand, while avoiding the detrimental effects of overprotection on adjacent, newer pipelines with high efficiency coating systems. Keywords: CP, cathodic protection, multiple pipelines, multi-pipeline ROW, right-of-ways, remote monitoring management, INTRODUCTION Enbridge owns and operates a sophisticated pipeline network of approximately 25,000 km. The mainline system comprises routings of two (2) to seven (7) pipelines within the same corridor. The complexity of the ROWs has increased over time as new pipelines were introduced and connected to common legacy CP systems. Consequently, the ROWs now include several combinations of pipelines having various diameters, coating types and current demands. The portion of mainline pipeline system which is the subject of this study can be characterized as follows: The pipeline vintage ranges from early 1968 to 2010; The diameter varies from 20 to 42 inch; The 2 primary coating types are: Polyethylene (PE) tape wrap and Fusion Bond Epoxy (FBE); The pipelines were backfilled with native soils with diverse characteristics. The lines have been opencut within river beds at the crossings of the water ways; with some instances of Horizontal Directional Drilled (HDD s) sections. The average distance between the anode beds and valve stations is 8 and 10 km, respectively. Valve stations are potential candidates for CP current loss through grounded structures; in particular utility neutrals, which have been mitigated through the implementation of DC decoupling devices The typical CP system consists of an impressed current rectifier coupled to a remote, shallow conventional groundbeds containing vertical anodes surrounded by coke breeze backfill. Each pipeline is individually connected to the rectifier via common bus bar through a junction box for individual current monitoring. An intensive campaign was initiated by the Operator to investigate the parameters and sensitivities that impact CP system performance. The objective of the study was to execute an in-depth review and analysis of the various options for monitoring, measuring, and controlling cathodic protection (CP) levels of the electrically continuous structures within shared right-of-way corridors and then implement corrective measures accordingly. Background CP potentials in electrically connected multiple pipeline corridors are primarily determined through a conventional annual survey process that meets regulatory requirements. The Company supplements these efforts with enhanced system monitoring techniques such as Close Interval Potential Surveys (CIPS/ CIS), voltage gradient (ACVG/ DCVG), or other indirect inspection techniques outlined within SP0502. Indirect inspections are intended to identify and assess the severity of coating faults, other anomalies and areas where corrosion activity was or still is occurring. Ideally, through successive 2

3 applications of these techniques, a pipeline operator should be able to identify and address locations where corrosion is or was active. The NACE ECDA process takes this practice several steps forward and integrates information on a pipeline s physical characteristics and operating history (preassessment) with data from multiple field examinations (indirect inspections) and pipe surface evaluations (direct examinations) to provide a more comprehensive integrity evaluation with respect to external corrosion (post assessment). (1- ANSI/NACE; SP0502, 2008) Standard application of these enhanced monitoring techniques can however, return inconsistent results in multiple pipeline ROW situations. It is generally recognized that CIS along multiple pipeline corridors yield ON potentials that are a mixed, or geometrically averaged potential of some or all of the pipelines having proximity to the reference cell. Similarly, Off potentials may include sources of error associated with a rebalancing of potentials between protected structures, each having different levels of polarization. The cathodic/anodic current exchange between multiple pipelines may not stabilize within the typical OFF cycle of an interrupted survey to provide opportunity for obtaining a valid polarized value. An accurate and reliable OFF potential measurement is essential to evaluate CP effectiveness of the pipe when applying the -850mV CSE (Copper Sulfate Electrode) or 100mV shift criteria. (2- NACE; SP0169, 2013) In some instances, the indirect inspections have not provided information accurate enough to reliably understand CP sufficiency within the multiple pipeline ROW. The Company has documented several CP survey locations that were incorrectly classified as being either adequately protected or sub-criterion due to the errors in the measurement process. For decades, CP criteria has been an enduring issue; exhaustively scrutinized, studied and debated; however it continues to remain challenged as external corrosion is repeatedly and persistently discovered (3- R.A. Gummow, 2012). Perhaps some of the controversy should not necessarily be attributed to questionable or invalid criteria, but rather the result of erroneous field information having been applied. A number of factors can influence On and Off potential measurements (4- NACE TM0497, 2012), including: 1. IR drops through the soil 2. Foreign-generated DC currents 3. Capacitive effects 4. Chemical environment of the soil 5. Current generated from dissimilar levels of polarization between the electrically continuous structures The errors in conventional CP monitoring information can be demonstrated through ILI metal loss programs. Annual cathodic survey results consistently report achievement of protection criteria in multipipeline corridors but; newer pipelines with non-shielding CP compatible coating systems continue to have active external metal loss features identified from ILI results. In-line inspection techniques (MFL or US) determines areas of metal loss activity and corrosion rates can be calculated from consecutive measurements; however these methods do not provide the root cause of the corrosion mechanism. Balancing the application of CP in a multiple ROW configuration has been recognized as problematic since the early 1990 s. An industry initiative from that period identified the following issues while attempting to monitor cathodic protection levels using surface reference electrodes: Errors in ground level on- and off-potentials due to the interaction of two adjacent pipelines in the same right-of-way can be significant under certain conditions. Significant error due to interaction between pipes in a bare - bare pipe combination is limited to onpotentials. No significant interaction was observed for off-potentials. Significant error due to interaction between pipes in a bare - poorly coated pipe combination is limited to the coated pipe. Errors can be significant for both the on and off-potentials measured for the coated pipelines. Potentials measured over the bare pipe accurately reflect potentials of the bare pipe. Significant error due to interaction between pipes in a poorly coated - well coated pipe combination is limited to the well coated pipe. Errors can be significant for both the on- and off-potentials measured for 3

4 the well coated pipeline. Potentials measured over the poorly coated pipe accurately reflect potentials of the poorly coated pipe. Increasing spacing decreased the error due to two pipeline interaction. Decreasing pipe depth decreased the error due to two pipeline interaction. Increasing potential difference decreased the error due to two pipeline interaction for the bare - bare pipe on-potential condition only. For all other conditions, the effect of potential difference was negligible. Increasing resistivity decreased the error due to two pipeline interaction for on potential measurements. No effect of resistivity was observed for off-potential measurements. Regression equations were developed for calculating percent interaction for a wide range of pipeline/soil conditions. Analysis procedures were developed to calculate errors due to interactions for field data. The calculations require on- and off-potentials over each pipeline, no other special measurements are required. For a pipeline crossing situation, the ground level off-potential reflects the off potential of the top pipe even when the bottom pipe is bare and the top is coated (exception may be for a very well coated pipe). For a given pipeline geometry, the parameter that defines coating quality and controls the interaction effects is the coating resistivity to soil resistivity ratio. For a given coating quality, as the soil resistivity varies, the coating resistivity is also expected to vary. The ground water that fills the coating pores or holidays, in part, establishes the coating resistivity. (5- CORTEST Columbus Technologies, Inc., October 29, 1993) Although awareness of the subject has obviously existed; the ability to effectively measure and manage cathodic levels was limited by the technologies available at that time. The preceding conclusions also coincide with a period when digital memory was expensive, and any relevant data measurements were logged very discerningly. Advances in electronics and portable power capacity over the past 20 years, has now enabled unprecedented access to immense volumes of information that can be transmitted almost instantaneously from remote locations very economically. The capability of computer modeling applications has progressed significantly to the point where sophisticated and realistic simulations can be generated from powerful computational algorithms which incorporate a multitude of variables. The industry no longer faces the dilemma of data rationing, but rather one of effective management and utilization of the massive, readily obtainable information sets. A new approach has been implemented by the Operator using the following state-of-the-art technologies: 1. CP coupons with stationary reference cells & data loggers/rmu s 2. remote monitoring of rectifier outputs 3. soil resistivity surveys 4. in-line cathodic protection current mapping inspection 5. advanced computational modeling 6. Correlation with ILI metal loss (MFL and Ultrasonic) and Inertial / GPS data 7. Strategic cross-bonding of commonly protected pipelines This rigorous study was initiated 2 years ago for a 625 km (445 mi) common corridor consisting of 4 pipelines of various sizes and dissimilar coating efficiencies. The results of the above techniques have been compared with ILI metal loss data with the objective of correlating the modeling results with wall loss measurements, to find the root cause of the corrosion attack. Effective remediation measures can then be employed for pipeline integrity optimization. Applied Technologies The Operator has elected using the aforementioned technologies to obtain immense volumes of field data; subsequently serving as the key input to generating a progressive computational model of the multiple pipeline ROW CP profile. 4

5 CP Coupons in close proximity to a stationary reference electrode Dual Coupon Housing with a stationary copper/copper sulfate reference electrode has been installed at 418 locations along the pipeline routing. The coupons were installed in accordance with industry standards (6- ANSI / NACE Standard RP0104, 2004) as shown in Figure 1. One coupon is facing towards and connected to the pipeline, while the other coupon is facing in the opposite direction (180) and electrically isolated. The CP coupons provide native potentials (disconnected coupon) and ON/OFF potentials (connected coupon). The potentials are measured against the CSE stationary reference cell housed in a controlled electrically conductive backfill medium located between the two coupons, and can be substantiated with respect to a portable CSE reference cell at grade level. Figure 1: schematic representation of double coupon test station w/ integrated reference cell Remote monitoring units (RMU) RMU devices are installed at rectifiers for real-time monitoring of the DC current output of each individual pipeline, the rectifier DC total current and DC voltage (see Figure 2). Monitoring data is retrieved real-time through a web based application. The RMUs are also utilized on AC mitigation systems and in some instances on bonds with foreign pipelines. At some locations a negative DC current is measured by the device as can be seen for sites 7 and 17 in Table 1. It was observed that the sum of the individual currents (line 1 to 4) does not always equal the total current output of the rectifier. This unexpected phenomenon is believed to be related to the sampling rate of the RMU, where interrogation of the channels is not synchronized and recording of the measurements does not occur simultaneously. The timeframe to register the measurements can be in the order of seconds which may lend to susceptibility of being affected by the 120 Hz output ripple of typical tap set rectifiers, and/or influences by interrupted surveys on other nearby foreign CP systems. Shunt value will dictate the resolution capability of the current being recorded, so round off error can also play as a contributing factor. Operators must be aware of the capabilities, limitations and configurations of the equipment being employed to ensure it is suitable for the purpose intended. 5

6 Figure 2: Typical installation of rectifier c/w RMU installation Table 1 - Example Data from Remote Monitoring Units DC 42 FBE 20 FBE 24 FBE 34 PET Site DC Volts Amps / V / / V V / / V V V V V V / / V V V V V V V V V V Total Soil resistivity survey Soil resistivity is measured at various locations during the design and installation of new or replacement anode bed designs. All related data from rectifier locations has been incorporated into the model parameters. The Operator has supplemented the model by using soil resistivity measurements along 6

7 the ROW, between rectifiers, that was collected during AC mitigation studies. Within regions of AC colocation, multiple layer soil models were developed from industry accepted Wenner four-pin method, in accordance with IEEE 1 (7- IEEE Standard 81, 2012), using the MEGGER Digital Earth Tester DET2/2. The electrode spacing varied from 2.5 feet to 100 feet and the soil resistivity measurements were used to derive equivalent soil structure models for the inductive and conductive interference analyses. Publicly available soil databases were also accessed to provide additional model information on soil types and characteristics for the relevant areas. The soil parameters of the model were further reinforced from data collected during integrity excavations and coupon installations where there was opportunity to gather information on ph and chlorides in addition to resistivity. All soil data collected from the various sources and techniques were then integrated into the computational model discussed later below. Cathodic Protection Current Mapper (CPCM ) inline inspection This inline tool inspects piggable pipeline sections under normal cathodic protection operations as depicted in Figure 3 below. The ILI technology is unique in that it is able to accurately measure the axial potential drop across the pipe wall caused by DC current while travelling inside the line at a speed of a few km/hr. The voltage drop is converted to axial current flow through Ohm s law I = E/R. By evaluating variations in axial current, the tool can: determine local current density (coating condition) verify the DC current output of the rectifiers detect location of bonds and short in the pipeline that leads to DC current loss or gain detect AC and DC interference currents Measuring current flow in the pipe wall will indicate the magnitude of current the pipe receives from the common CP systems and/or third party sources in the inspected section. Current from rectifiers are typically positive and negative (current coming from both sides of the pipe) whereas inadvertent continuity to grounded structures typically results in a radical change in current value while maintaining its polarity. The slope of the line current between rectifier locations is characteristic of the coating resistance. (8- D.Janda, 2013) Figure 3: Cathodic protection current monitoring ILI tool 1 Institute of Electrical and Electronics Engineers, Inc. (IEEE), 3 Park Ave, 17 th Floor, New York, NY Trade Name 7

8 Advanced computational modeling Elsyca CatPro software is a BEM/FEM based computational tool that simulates the CP and corrosion behavior of complex pipeline networks such as a multiple pipeline ROW. A model of the pipeline and CP asset is created which includes insulating flanges, groundings, interconnection bonds, anode beds, cables and rectifiers. The major parameters determining the effectiveness of a given CP system (with fixed geometry and anode configuration) are COATING QUALITY, SOIL RESISTIVITY and STUCTURE POLARIZATION. These parameters can vary along the structure which complicates the design and control of the CP system. Therefore, field data relating to the above mentioned parameters needs to be collected and continually integrated in the model ensuring the proper values are addressed. The resolution of the model is determined by a user-defined pipeline section length for which the above constraints are entered case by case. Typically, the first simulation is performed by considering an average soil resistivity and using blueprint values for the coating resistance. The rectifier output current is imposed in the model and the simulated ON potentials at grade level are compared with the measured field data at test stations from annual survey results. A further refinement of the model is then possible for the coating resistance (ohmm 2 ), local soil resistivity (ohmm) and polarization data (I-V curve) depending on the availability and accuracy of the data. The model calculates the following parameters for the entire pipeline network: pipe-to-soil ON at any depth IR-free potential at pipe surface current density leaving/entering the pipe section axial or line current through the pipe wall rectifier voltage and current current through bonds and cables In this study the field data retrieved from the RMU s, coupons, soil resistivity surveys and CP ILI inspection were used to refine the model for coating condition and polarization behavior. For example the measured axial current of the CP ILI tool is compared with the simulation results. This comparison complements the model particularly when there are unintentional connections to grounded systems, such as at valve stations. The measured axial current allows adjustment of the coating resistance for the various pipe sections defined. Additionally, measured ON potentials from the coupons and pipe is also used to verify the obtained coating resistance. Once the connections and coating resistance are tuned, the model is further refined by considering the native, OFF potential and current demand acquired from the coupons. The coupon data is used to deliver representative polarization levels for specific regions. Once the model is in place, a virtual in-situ system can be used to analyze the CP effectiveness and better understand the behavior of each pipeline. The modeling technology was further extended to explore the impact of different scenarios such as: eliminating accidental current drains at valve stations introducing shunt resistors to control the back current flow towards the rectifier repositioning the anode beds Trade Name 8

9 RESULTS Although the full investigation and analysis is still ongoing at the time of writing, some interesting preliminary results are discussed. Some rectifiers were found to be backfeeding current TO the pipeline rather than draining current FROM the pipeline. This is not uncommon in systems with multiple pipelines being protected by a common rectifier. Field personnel and equipment must, respectively be diligent and capable to correctly document the polarity when measuring negative drain current values. The region outlined within Table 1 has been selected since unfavourable ON potentials were measured during annual surveys. The total current (DC Amps) and overall voltage (DC Volts) is monitored as well as the current of each individual line. It can be noted that the individual current of newer lines can have a negative sign while in the case of the old line, the current is always positive. In the area between Sites there is a high concentration of rectifiers where there is significant current demand for a relatively short pipeline section ( about 10 miles long). The following information corresponds with the coupon installation program. Each of the following data sets were sampled through a 1 minute duration and recorded at a frequency of 60 measurements/second (3600 data points/graph). Figures 4 and 5 demonstrate the change in pipe-tosoil potentials once the coupon is physically disconnected from the pipeline at the 30 second point in the test. 34 PE Tape FBE FBE 2007/08 42 FBE Figure 4: Protected Coupon PSP w.r.t. portable CSE at-grade/over pipeline Vs. Time (sec) 34 PE Tape FBE FBE 2007/08 42 FBE Figure 5: Protected Coupon PSP w.r.t. stationary/close proximity CSE Vs. Time (sec) 9

10 Figures 4 & 5 above, clearly demonstrate the possible shortcomings of performing a CIS through this region since the OFF potentials would be recorded as being quite similar from line to line. However, the actual polarization of the structures is not fully realized until the coupon has been electrically disconnected; with some degree of error still occuring when the measurement is made from grade level where a more optimistic level of polarization is being depicted. Table 2 - Summarized Soil Resistivity Data MP Resistivity [ohm m] Table 2 demonstrates significant variability of soil resistivity along the ROW, particularly between MP175 and MP192. It should be noted that within this region a transition occurs from a poorly drained silt loam to a extensively to poorly drained sandy soil. A girth weld inventory with corresponding GPS coordinates was established from the CP ILI enabling all information to be consistent for correlation with historical metal loss inspections. The CP ILI detected several undocumented drains where a significant magnitude of current was draining back to the pipeline and creating a substantial burden to the CP system s effectiveness. The majority of such locations were discovered at mainline valves and typically involved conduit for supplying power to motor operators. Acceptable induced AC levels were reported by the CP ILI confirming effectiveness of recent AC mitigation efforts within defined segments. Conversely, a substantial rise and fall in the AC data plot was identified indicative of persistent AC voltage accumulating and discharging to ground in an uncontrolled manner. Remedial action was subsequently initiated and the issue resolved. An initial model was created for the ROW section between MP136 and MP227. The rectifier outputs from Table 1 were applied in the model and known shortings at valves grounding and casings were also considered. In total, 12 different sections in the ROW has been defined where a different coating resistance is assigned to the pipes. The blueprint values are based on the coating type and pipe vintage and further refined based on the ON potential measurements of the latest annual test station survey. Table 3 summarizes the coating resistance results and an average soil resistivity of 55 ohmm was initially considered in the model. 10

11 Table 3 - Assumed Coating Resistance Values in the Model 34 PET FBE 2007/ FBE FBE 2008 min 3.25E E E E+03 max 1.74E E E E+05 average 1.76E E E E+05 Simulation results based on the blueprint values for the coating resistance are shown in Figures 6 to 9. Figure 6 outlines the simulated ON-potential values of the individual lines compared with the measured mixed or average potential at the test stations. The most unfavourable ON-potentials are found in the middle of the ROW section between MP180 and MP197. The current density per line is simulated and from Figure 7 it can be seen that the oldest pipe (34 PE circa 1968) has negative or cathodic current densities over the entire trajectory. The results of the newer pipes (Line 2, 3 and 4) is shown in Figure 8. Figure 9 depicts a focused region between MP182 and MP201 where Line 2 and 4 are exhibiting anodic or corrosion current densities, albeit rather low, namely 2.17 to 22.6 microa/m 2. ON potential [v vs CSE] Line 2 Line 4 Line 3 Line developed length [mi] Figure 6: simulated ON potentials of pipelines compared with test station data 0.0E E 03 Current density [A/m 2 ] 4.0E E E E 02 Line 1 1.2E E Figure 7: simulated current density of oldest pipeline in ROW 11

12 5.0E E+00 Current density [A/m 2 ] 5.0E E E 04 Line 2 Line 3 Line 4 2.0E Figure 8: simulated current density of newer pipelines in ROW Current density [A/m2] 3.0E E E E E E E E 05 Line 2 Line 3 Line E E E E developed length [mi] Figure 9: zoom-in near section with anodic current density CP axial current measurements from ILI tool Further refinement of the computational model is underway based on CP ILI data. CP inline inspection was performed on Line 2 and 4 respectively. Line 4 was surveyed for its entire length of 742 km (461 mi) while for line 2 reliable data was only available for the last section of 294 km. Figure 10 shows the results of the line current. Both pipelines are in the same ROW from the beginning but Line 2 leaves the ROW after 518 km (321 mi). The section where CP ILI data is available for both pipelines is between 446 and 518 km ( 277 and 321 mi). The graphs demonstrate: Both lines behave completely different in the ROW attributed to variances in installation The region between MP 190 and MP 201 with high rectifier current output is apparent The large negative current peak (-6 amps) in Line 4 coincides with the rectifier at MP190 while the large positive peak (4 Amps) coincides with the rectifier at MP196. It is assumed that a grounded structure may inadvertently be connected to the pipe at those locations, influencing the CP current flow 12

13 line current [A] CPCM Line 2 CPCM Line developed length [mi] Figure 10: measured line current by CP ILI tool Several undocumented drains are reported having a significant magnitude of current flowing to the pipeline creating a substantial burden to the CP system s effectiveness. The majority of such locations were discovered at mainline valves and typically involved conduit supplying power to motor operators. The CP ILI data is used to further refine the model. A separate model of Line 4 was built (34 PE tape 1968) and the current sources and drains values from the CP ILI data have been added. A blueprint value of the coating resistance of 1e04 ohmm 2 for the complete line output the most reasonable results. As can be seen in Figure 11 there is a decent correlation between the measured and simulated line currents. Some regions where a discrepancy is observed requires further refinement to the model through adjustment of coating resistance and soil resistivity values. Note that the blueprint value is smaller than the one used from the initial model iteration (see Table 3). Consequently, the sensistivity of coating resistance was investigated in the Line 4 model as demonstrated in Figures 12 & Line current [A] CPCM blueprint developed length [mi] Figure 11: measured line current of Line 4 compared with blueprint simulation 13

14 6 4 2 Line current [A] scenario 1 scenario developed length [mi] Figure 12: effect of coating resistance on line current in the model 1.E+05 Coating resistance [ohmm 2 ] 1.E+04 1.E+03 scenario 1 scenario developed length [mi] Figure 13: coating resistance values used within Figure 12 14

15 CONCLUSIONS Achieving effective cathodic protection on multiple pipelines in a mutual corridor, using common current source systems is a complicated and challenging assignment. Although the complexity and difficulties relative to the subject were recognized decades ago; the industry is presently in a position where the technological advancements of several fields have made it to possible to logically and strategically contend with the situation. Pipeline operators are able to exploit a multitude of technologies and collect the necessary information to create representative models of cathodic protection levels of pipelines under such configurations. However, caution must be exercised during the data acquisition process, as there are many opportunities to record erroneous information pertaining to cathodic protection of pipelines; particularly in the case of polarized or instant Off potentials. Therefore, awareness of such errors is imperative and gathering of accurate field measurements is critical for subsequent use as simulation input. Accomplishing a reliable model can provide the pipeline operator edified direction for making essential CP system adjustments or modifications to minimize or ultimately eliminate external corrosion on pipelines installed with non-shielding coating systems. The models should be used in conjunction with ILI metal loss inspections where the correlation of results will identify areas that can proactively be mitigated before repair criteria is reached; thereby eliminating costly excavations and substantially reducing the risk of failure. ACKNOWLEDGEMENTS The authors would like to recognize and sincerely thank Sherif Hassanien and Ryan Sporns for their continual support, dedication and devotion towards advancing pipeline integrity management. REFERENCES 1- ANSI/NACE; SP0502. (2008). Standard Practice - Pipeline External Corrrosion Direct Assessment Methodology. Houston, TX: ANSI (American National Standards Institute) / NACE International. 2- NACE; SP0169. (2013). Standard Practice - Control of External Corrosion on Underground or Submerged Metallic Piping Systems. Houston, TX: NACE International. 3- R.A. Gummow, W. F. (2012). Would the Real -850 mvcse Criterion Please Stand Up. Corrosion 2012; Paper No. C Salt Lake City, UT: NACE International. 4- NACE TM0497. (2012). Standard Test Method - Measurement Techniques Related to Criteria for Cathodic Protection on Underground or Submerged Metallic Piping Systems. Houston, TX: NACE International. 5- CORTEST Columbus Technologies, Inc. (October 29, 1993). Multiple Pipelines In Right-Of-Way: Improved Pipe-To-Soil Potential Survey Methods. Houston: PRCI Catalog No. L51692e; Contract # PR ANSI / NACE Standard RP0104. (2004). Standard Recommended Practice - The Use of Coupons for Cathodic Protection Monitoring Applications; Item No Houston, TX: ANSI (American National Standards Institute) / NACE International. 7- IEEE Standard 81. (2012). Guide for Measuring Earth Resistivity, Ground Impedance, and Earth Surface Potentials of a Ground System. New York, NY: Institute of Electrical and Electronics Engineers, Inc. (IEEE). 8- D.Janda, C. B. (2013). A New Approach to Pipeline Integrity Combining In-Line Inspection and Cathodic Protection Simulation Technology. CORROSION 2013, Paper No (p. 5). Orlando, FL: NACE. 15