C2012-0001674 Evaluation of FBE Coatings for High Temperature Pipeline Applications Jose Martin Lizcano Contreras, MSc and Miguel Mateus Barragan, MSc ECOPETROL S.A Km 7 Via to Piedecuesta Piedecuesta, Santander Colombia Alban Jaimes Suárez, MSc UT TIP Petrolabin Ltda Km 7 Via to Piedecuesta, Santander, Colombia Miguel Manrique Rojas, Eng CIMA Km 7 via to Piedecuesta, Santander, Colombia ABSTRACT In oilfields from Colombia, the surface operating temperatures of pipelines are around 120°C. Actually, Canadian and ASTM standard tests set the conditions for Cathodic Disbonding Testing to maximum temperature of 95 °C, while our scope for coating evaluation is between 95 to 150 °C. To select for higher performance coatings systems, we have developed a testing protocol to be applied at the factory, in the laboratory and in the field to assess the performance of coatings for operating conditions between 95 to 150°C. The protocol involved the following tests: dry film thickness, porosity, mechanical, abrasion resistance test, impact and elongation, adhesion, wet adhesion, immersion in chemical solution, cathodic disbonding and electrochemical impedance. The results in the laboratory can be correlated between the glass transition temperature and the electrochemical response. To clarify damage level found in the coatings evaluated. As a result of this work was found a reliable methodology for evaluating coatings at temperatures above 95°C. A good correlation was found in the results of electrochemical impedance tests and cathodic disbondment evaluated to 150°C. Key Words: electrochemical impedance, disbonding, epoxy, cathodic disbonding, permeation, pore of resistance. ©2012 by NACE International. Requests for permission to publish this manuscript in any form, in part or in whole, must be in writing to NACE International, Publications Division, 1440 South Creek Drive, Houston, Texas 77084. The material presented and the views expressed in this paper are solely those of the author(s) and are not necessarily endorsed by the Association. Luis Rojas Laurens - Invoice 369986 downloaded on 1/9/2024 12:46:13 AM Single-user licence only, copying/networking prohibited INTRODUCTION A research as need arises from the operation in oilfield, where fluids are produced with temperatures above 120°C, the soil around the buried pipeline has a lower temperature, this condition in combination with the high humidity generates a lot of steam at the interface pipeline / soil, affecting and degrading the coating. Currently, the standards to evaluate coatings have a limit in the testing temperature, 60°C for ASTM(1) G42 and 95°C for CSA(2) Z245.20-101. In this paper, we present a methodology to evaluate the coating performance; these tests involved mechanical evaluation of abrasion resistance, impact and elongation; also immersion and electrochemical tests such as; adhesion, wet adhesion, immersion in chemical solutions, cathodic disbonding and electrochemical impedance. With these investigations, we developed a testing methodology to select coatings for high temperature, as much as 150°C. BACKGROUND According to our knowledge, in the open literature there are not any standard test methods for evaluating epoxy coating performance above 95 °C. Kirkpatrick3, stated that test methods to predict the long-term coating performance of fusion-bonded epoxy coatings at elevated temperatures need to be developed. Papavinasam and Revie4 also stated that no industry standard exists to test coating performance at high temperature. In Table 1 It is a summary of standard Cathodic Disbondment test methods developed by different International Organizations. Table 1 Summary of International Standards on Cathodic Disbondment Test 5 Voltage Temperature Standard (Vs Cu/CuSO4) (°C) Duration ASTM(1) G86 -1.45 to -1.55 V 25 30 days ASTM(1) G197 -1.45 V 25 3 – 18 months ASTM(1) G421 -1.5 V 60 30 days ASTM(1) G808 -1.45 to -1.55 V 25 60 days ASTM(1) G959 -3.20 V 25 90 days CSA(2) Z45.21 (Sec -1.50 V 20 – 95 28 days 10 12.3) NACE RP039411 -1.50 V 66 28 days Shukla12 et al, established that EIS is a good tool for coating deterioration research, specially on a metal. EIS provides two very important pieces of information: (i) the absolute value of resistance and change in capacitance of the organic film that relates to water uptake, and (ii) the value of charge transfer resistance at the coating and metal interface. The deviation in capacitance and charge transfer resistance is measured in terms of coating impedance. Development of pores in the coating or disbonding of an electrolyte-saturated film at the onset of corrosion causes deviation from purely capacitive behavior and results in a decreased charge transfer resistance. Al – Borno et al13, developed a method to run cathodic disbonding test at high temperatures. They design a cell for high temperatures; this cell test includes a cooling jacket which can be thermostatically controlled easily allowing that higher test temperatures can be used without electrolyte evaporation up to 180°C / 356°F . (1) (2) American Society for Testing and Materials Canadian Standards Association “Plant-applied external coatings for steel pipe, May 2010” ©2012 by NACE International. Requests for permission to publish this manuscript in any form, in part or in whole, must be in writing to NACE International, Publications Division, 1440 South Creek Drive, Houston, Texas 77084. The material presented and the views expressed in this paper are solely those of the author(s) and are not necessarily endorsed by the Association. Luis Rojas Laurens - Invoice 369986 downloaded on 1/9/2024 12:46:13 AM Single-user licence only, copying/networking prohibited EXPERIMENTAL PROCEDURE Figure 1 shows a flow chart describing the proposed methodology. In addition to the traditional tests such as; dry film thickness and porosity for quality control of the coating application, we propose the use of mechanical, immersion, catholic disbonding and electrochemical impedance tests. Samples were prepared in the pipeline coating manufacturing plant in Cartagena, Colombia. Start Mechanical Tests EIS, Immersion and CD Tests Abrasion Resistance Impact Resistance Flexibility Test Adhesion Wet Adhesion Immersion tests in Chemical Solutions Cathodic Disbonding at 130, 150°C Electrochemical Impedance at 130, 150°C Figure 1: Methodology to evaluate and select coatings for high temperature. Each of the tests is described below: Abrasion Resistance: This test was conducted at two conditions. a) As received, after application and curing of the coating, b) Aging samples for 28 days at 150°C, subsequently cooled to room temperature to perform the testing in accordance with ASTM(1) D406015 standard and CS – 17 wheels were used. Impact Resistance: The impact test was in accordance with ASTM(1) D279416 standard. This test was conducted at two conditions. a) Aging samples for 28 days at 150°C, subsequently cooled to room temperature to perform the testing, b) Aging samples for 2 days at 150°C, subsequently, to perform the testing at 150°C. Flexibility of Coatings: Following CSA(2) Z245.20-102 standard, section 12.1, the samples were bent until failure. Adhesion: The testing was in accordance with ASTM D4541 standard. This test was conducted at two conditions. a) Aging samples for 28 days at 150°C, subsequently cooled to room temperature to perform the testing, b) Aging samples for 2 days at 150°C, subsequently, to perform the testing at 150°C. It should be noted that for this test, the maximum pulling stress is limited by the tester equipment, for FBE coating is common to support the load without pulling out, in case of degradation if it is possible take it as criterion of pass / fail. Wet Adhesion: The samples were exposed in water at 150°C for 28 days. ©2012 by NACE International. Requests for permission to publish this manuscript in any form, in part or in whole, must be in writing to NACE International, Publications Division, 1440 South Creek Drive, Houston, Texas 77084. The material presented and the views expressed in this paper are solely those of the author(s) and are not necessarily endorsed by the Association. Luis Rojas Laurens - Invoice 369986 downloaded on 1/9/2024 12:46:13 AM Single-user licence only, copying/networking prohibited The test was in accordance with CSA(2) Z245.20-103 general standard specifications, section 12.14. Immersion tests in chemical solutions: Aging samples in an oven for 28 days at 150°C, subsequently, the samples were exposed to two different pH fluids (pH 3 and pH 7) during 400 hours at 95°C. The values of pH were chosen in function of the pH of the soil which the operating conditions are above 95ºC. Normally, the pH of the soil in the oilfields is around of 4 – 6.8. Both solutions have 10% NaCl. It should not be changes in color, corrosion products, blistering, softening or delamination. Cathodic Disbondment: Test temperatures of 130 and 150°C on steel surface with applied voltage of 1.5 Volts Vs SCE. Electrochemical Impedance: Test temperatures of 130°C and 150ºC on steel surface. Coating samples were applied in the factory and the aging was done in an oven, which remained constant at 150ºC. The objective of the aging was to accelerate the degradation process in the coating system. To conduct electrochemical impedance and cathodic disbonding test, we designed a glass cell with external water cooling. Figures 2 and 3 detail the assembly and cell used. Figure 2: Assembly to run Cathodic Disbonding and Electrochemical Impedance test under conditions of 130 and 150ºC. Figure 3 shows cell design, the cell has a volume of 220mL with a solution of 3% NaCl. To achieve the desired temperature of 150°C for cathodic disbondment, we used two heating means, shot metal and sand. For shot metal, the temperature in shot metal bed was of 205°C, the steel temperature was 150 ± 5°C, with the cooling system, the electrolyte temperature was maintained around 60 ° C, enabling the possibility to run electrochemical tests. For sand, the temperature in sand bed was of 260°C, the steel temperature was 150 ± 5°C, with the cooling system, the electrolyte temperature was maintained around 60 ° C, enabling the possibility to run electrochemical tests. ©2012 by NACE International. Requests for permission to publish this manuscript in any form, in part or in whole, must be in writing to NACE International, Publications Division, 1440 South Creek Drive, Houston, Texas 77084. The material presented and the views expressed in this paper are solely those of the author(s) and are not necessarily endorsed by the Association. Luis Rojas Laurens - Invoice 369986 downloaded on 1/9/2024 12:46:13 AM Single-user licence only, copying/networking prohibited Figure 3: Design of Glass Cell for electrochemical tests. ©2012 by NACE International. Requests for permission to publish this manuscript in any form, in part or in whole, must be in writing to NACE International, Publications Division, 1440 South Creek Drive, Houston, Texas 77084. The material presented and the views expressed in this paper are solely those of the author(s) and are not necessarily endorsed by the Association. Luis Rojas Laurens - Invoice 369986 downloaded on 1/9/2024 12:46:13 AM Single-user licence only, copying/networking prohibited RESULTS AND DISCUSSION Characterization Tests Table 2 shows the characterization tests results. The systems A and B have the highest Tg among all of the samples. Test / System Gel Time Density Cathodic Disbondment Calorimeter Table 2 Characterization Tests Unit A Seconds 9 g/cc 1.53 mm 2.37 Tg.1 (°C) 56.3 Tg.2 (°C) 133.5 119 H (J/g) B 9 1.37 1.83 56.4 154 158 C 14 1.42 3.16 60.7 97.7 67.6 D 15 1.59 3.05 61.2 104.6 48.3 Abrasion Resistance Table 3 shows the abrasion test results. System D did not present significant changes between without and with aging, it is noteworthy that after aging in oven at 150°C, all test systems showed a color change due to thermal degradation and generated an increasing in coating hardness. The samples A, B and C showed increases in the abrasion resistance in samples after aging. System A – single layer B – single layer C – dual layer D – dual layer Table 3 Abrasion Resistance Results Wear Index Observations Wear Index (mg/cycle) (mg/cycle) 31 Without aging 68 43 Without aging 74 55 Without aging 72 75 Without aging 76 Observations With aging With aging With aging With aging Figure 4: Changes in Abrasion Resistance. ©2012 by NACE International. Requests for permission to publish this manuscript in any form, in part or in whole, must be in writing to NACE International, Publications Division, 1440 South Creek Drive, Houston, Texas 77084. The material presented and the views expressed in this paper are solely those of the author(s) and are not necessarily endorsed by the Association. Luis Rojas Laurens - Invoice 369986 downloaded on 1/9/2024 12:46:13 AM Single-user licence only, copying/networking prohibited Impact Resistance Table 4 shows the results of impact test. System C did not present significant changes without and with aging. The systems A, B and D showed a loss in the impact resistance. This indicates that there is a negative relation between the properties of Abrasion and Impact resistance. System A – single layer B – single layer C – dual layer D – dual layer Table 4 Impact Resistance Results Impact Failure Observations Impact (J) Failure (J) 7.5 Without aging 4.3 8.4 Without aging 6.8 5.4 Without aging 5.7 7.0 Without aging 5.2 Observations With aging With aging With aging With aging Figure 5: Changes in Impact Resistance. Flexibility Test Table 5 shows flexibility test results. The results reported below were obtained deflecting samples until failure. E = Elongation = 0.5d/R (1) °/PD = Grade / pipe diameter % E = 50d/R. d = OD of the pipe. R = Radius to the neutral axis of the circle to which the pipe can be bent to the maximum limit without any coating damage. Table 5 Flexibility Test Results without aging thickness System º/PD (FBE + metal) mm A – single layer 2.1 7.865 B – single layer 2.2 7.805 C – dual layer 3.3 8.03 D – dual layer 2.3 8.025 %E 1.89 1.91 2.88 1.97 ©2012 by NACE International. Requests for permission to publish this manuscript in any form, in part or in whole, must be in writing to NACE International, Publications Division, 1440 South Creek Drive, Houston, Texas 77084. The material presented and the views expressed in this paper are solely those of the author(s) and are not necessarily endorsed by the Association. Luis Rojas Laurens - Invoice 369986 downloaded on 1/9/2024 12:46:13 AM Single-user licence only, copying/networking prohibited Adhesion Test Table 6 shows adhesion test results. The system A showed an adhesion loss in samples with aging at 150°C for 28 days. System A – single layer B – single layer C – dual layer D – dual layer A – single layer B – single layer C – dual layer D – dual layer Table 6 Adhesion Test Results Value Percentage of MPa (psi) failures 60% Adhesive, 20.68 (3000) 40% Cohesive failure 100% Adhesive 20.68 (3000) Failure 100% Adhesive 15.86 (2300) Failure 90% Adhesive 15.51 (2250) Failure >22.06 (3200) Glue Failure >22.06 (3200) Glue Failure >22.06 (3200) Glue Failure >22.06 (3200) Glue Failure Observations Aging for 28 days at 150°C and test at room temperature Aging for 2 days at 150°C and evaluated at 150°C Wet Adhesion Table 7 shows wet adhesion test results. The immersion time was 28 days at 150ºC. The temperature of 150ºC was selected with the objective to simulate the real conditions and more critical. Table 7 Wet Adhesion Test Results Rated agreed to Coating System CAN Z245.20-10 A – single layer Rating 1 B – single layer Rating 1 C – dual layer Rating 1 D – dual layer Rating 1 In mechanical tests performed for impact, abrasion and pull off, it was observed an aging effect, because of the change in properties. Immersion tests in chemical solutions In the samples evaluated, from visual inspecting only color change was identify; no corrosion products were observed, neither softening and blistering of coating, which means a good chemical resistance of the samples. Table 8 shows test results. The coating systems suffered damage by the effect of temperature, however, when the samples were exposed to acidic and neutral fluids did not suffer any visual damage. ©2012 by NACE International. Requests for permission to publish this manuscript in any form, in part or in whole, must be in writing to NACE International, Publications Division, 1440 South Creek Drive, Houston, Texas 77084. The material presented and the views expressed in this paper are solely those of the author(s) and are not necessarily endorsed by the Association. Luis Rojas Laurens - Invoice 369986 downloaded on 1/9/2024 12:46:13 AM Single-user licence only, copying/networking prohibited Table 8 Immersion tests in chemical solutions pH 3 and pH 7 Coating System failure type A – single layer Strong Color Change B – single layer Strong Color Change C – dual layer Strong Color Change D – dual layer Strong Color Change Cathodic Disbonding Table 9 shows the cathodic disbonding test results at 150°C during 14 days. Table 10 shows the cathodic disbonding test results at 150°C during 14 days and 150 º C during 28 days. Samples C and D did not show changes in the cathodic disbonding. Table 9 Cathodic Disbonding results at 150ºC – 1.5V Vs SCE, 14 days. Maximum Radius System Photographic Register (mm) A – single layer 2.9 B – single layer 3.9 C – dual layer 3.8 ©2012 by NACE International. Requests for permission to publish this manuscript in any form, in part or in whole, must be in writing to NACE International, Publications Division, 1440 South Creek Drive, Houston, Texas 77084. The material presented and the views expressed in this paper are solely those of the author(s) and are not necessarily endorsed by the Association. Luis Rojas Laurens - Invoice 369986 downloaded on 1/9/2024 12:46:13 AM Single-user licence only, copying/networking prohibited System Maximum Radius (mm) D – dual layer 3.0 Photographic Register Table 10 Comparison between two Cathodic Disbonding tests CD CD (mm) at 150°C during (mm) at 150°C during System 14 days 28 days Voltage CD(mm) Voltage CD (mm) A – single layer -1.5V 2.9 -1.5V 4.8 B – single layer -1.5V 3.9 -1.5V 10.2 C – dual layer -1.5V 3.8 -1.5V 3.3 D – dual layer -1.5V 3.0 -1.5V 2.2 Electrochemical Impedance Table 11 shows the electrochemical impedance test results, at 150°C, for 30 days. This test is developed with the objective to evaluate the grade of water permeation in the coating. The results show a reduction in the protective properties of samples evaluated, comparing the behavior at 0 hours and 720 hours, except for sample A that shows a good behavior. The reduction percentage of protection is calculated in terms of pore resistance, as follows: % RP = (Pore Resistance at 30 days – 720 hours/ Pore Resistance at 0 day – 0 hours)*100 (2) Table 11 Electrochemical Impedance Test Results at 150ºC, 10000Hz – 0.01Hz – 10mV rms Vs OCP. Pore Resistance Pore Resistance %Reduction of Protection System 0 hrs ( ) 720 hrs ( ) 8 7 A – single layer 8.9x10 2.015x10 2.3 B – single layer 1.037x109 5.5x108 53 C – dual layer 1.16x109 5.3x108 45.7 D – dual layer 8.07x108 1.08x108 13.4 ©2012 by NACE International. Requests for permission to publish this manuscript in any form, in part or in whole, must be in writing to NACE International, Publications Division, 1440 South Creek Drive, Houston, Texas 77084. The material presented and the views expressed in this paper are solely those of the author(s) and are not necessarily endorsed by the Association. Luis Rojas Laurens - Invoice 369986 downloaded on 1/9/2024 12:46:13 AM Single-user licence only, copying/networking prohibited CONCLUSIONS A good correlation was found between electrochemical impedance tests and cathodic disbondment. The evaluated FBE coating systems showed thermal degradation on mechanical properties. At 150°C, the combined effect of voltage, time and temperature promotes a loss in the resistance to cathodic disbondment. A methodology was developed for coatings selection at temperatures above 95°C, which provides reliable and comparable results, which allow selecting different FBE coating systems. RECOMMENDATION The authors want to establish that this investigation is an input for developing the experimental basis of the new standards to evaluate FBE coating systems at high temperatures (>95°C). REFERENCES 1. ASTM G42 96(latest revision), “Standard Test Method for Cathodic Disbonding of Pipeline Coatings Subjected to Elevated Temperatures” (West Conshohocken, PA: ASTM). 2. CSA Z245.20-10, “Plant applied external coatings for steel pipe”. 3. D. Kirkpatrick, F. Aguirre, and G. Jacob. “Review of Epoxy Polymer Thermal Aging Behavior Relevant to Fusion Bonded Epoxy Coatings.” Proceedings of the CORROSION/2008 Conference, Paper 08037. Houston, Texas: NACE. 2008. 4. S. Papavinasam and R.W. Revie. “Coating for Pipelines.” International Workshop on Advanced Research & Development of Coatings for Corrosion Protection. Golden, Colorado: Colorado State University. 2004. 5. S. Papavinasam, S. Attard, and R.W. Revie. “Modified Cathodic Disbondment Testing of External Polymeric Pipeline.” Proceedings of the CORROSION/2007 Conference, Paper 07021. Houston, Texas: NACE. 2007. 6. ASTM G8 - 96(latest revision), “Standard Test Methods for Cathodic Disbonding of Pipeline Coatings” (West Conshohocken, PA: ASTM). 7. ASTM G19-04(latest revision), “Standard Test Method for Disbonding Characteristics of Pipeline Coatings by Direct Soil Burial” (West Conshohocken, PA: ASTM). 8. ASTM G80(latest revision), “Standard Test Method for Specific Cathodic Disbonding of Pipeline Coatings” (West Conshohocken, PA: ASTM). 9. ASTM G95 – 07(latest revision), “Standard Test Method for Cathodic Disbondment Test of Pipeline Coatings” (West Conshohocken, PA: ASTM). 10. CSA Z245.21-10, “Plant applied external coatings for steel pipe”. ©2012 by NACE International. Requests for permission to publish this manuscript in any form, in part or in whole, must be in writing to NACE International, Publications Division, 1440 South Creek Drive, Houston, Texas 77084. The material presented and the views expressed in this paper are solely those of the author(s) and are not necessarily endorsed by the Association. Luis Rojas Laurens - Invoice 369986 downloaded on 1/9/2024 12:46:13 AM Single-user licence only, copying/networking prohibited 11. NACE RP0394-2002(latest revision), “Standard Recommended Practice Application Performance, and Quality Control of Plant Applied, Fusion Bonded Epoxy External Pipe Coating”. 12. P. Shukla, R. Pabalan and L. Yang. “On Development of Accelerated Testing Methods For Evaluating Organic Coating Performance Above 100 °C”, Proceedings of the CORROSION/2010 Conference, paper 10006. Houston, Texas, NACE. 2010. 13. A. Al – Borno, M. Brown, S. Rao. “High Temperature Cathodic Disbondment Tests”, Proceedings of the CORROSION/2010 Conference, paper 10008. Calgary, Alberta, NACE. 2010. ©2012 by NACE International. Requests for permission to publish this manuscript in any form, in part or in whole, must be in writing to NACE International, Publications Division, 1440 South Creek Drive, Houston, Texas 77084. The material presented and the views expressed in this paper are solely those of the author(s) and are not necessarily endorsed by the Association. Luis Rojas Laurens - Invoice 369986 downloaded on 1/9/2024 12:46:13 AM Single-user licence only, copying/networking prohibited