THE INFLUENCE OF FLOW SPEED AND TIME PERIOD ON RUBBER LINING DAMAGE IN CIRCULATING WATER LINE OF STEAM POWER PLANT CONDENSER

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1 THE INFLUENCE OF FLOW SPEED AND TIME PERIOD ON RUBBER LINING DAMAGE IN CIRCULATING WATER LINE OF STEAM POWER PLANT CONDENSER Dita Fatmala 1, Markus Diantoro 2, Nasikhudin 3 1 Student, Physics Department, Faculty of Mathematics and Science, State University of Malang 2 Lecturer, Physics Department, Faculty of Mathematics and Science, State University of Malang 3 Lecturer, Physics Department, Faculty of Mathematics and Science, State University of Malang address: dita.fatmala@hotmail.com Abstract Rubber lining is the one of lining that made by rubber. Rubber usually used for protection of both the interior of tanks for acids and alkalis and of the exterior of pipes in the splashzone. Steam Power Plant Paiton Unit 7 & 8 3 is the one of power plant that provides electricity to the area of Java and Bali. To provide electricity for the area of Java and Bali, Steam Power Plant Paiton Unit 7 & 8 and 3 are equipped with devices that support the overall system. One of these devices is circulating water line of condenser that used as cooler device. The rubber lining applied inside the circulating water line to prevent corrosion. This research aim to find the scratches, blisters, and overlaps on the surface of rubber lining, conducted direct inspections in the location that has been determined and were photographed using digital camera. Inspection method that has been used is the visual inspection method. To measure the thickness changes on rubber lining, conducted thickness test using electronic thickness gauge (type: PosiTector 6000). Last, to find the pinholes on the surface of rubber lining, conducted holiday test using High Voltage Spark Tester. The number of scratches, blisters, overlaps, thickness changes, and pinholes expressed in percentages (%). The result of this research is increase in flow speed of fluid and time period of fluid flow through the line will cause the rubber lining damage more severe. To optimize the rubber lining as corrosion protection in circulating water line of condenser, require to decrease the flow speed of fluid, refining piping design, reducing the rubber lining joint and conduct the inspection more intensive than usual for minimize the rubber lining damage. Keywords: Flow Speed, Time Period, Rubber Lining, Circulating Water Line, Condenser INTRODUCTION Lining is the one of corrosion protection method as well as paint coatings. The term lining is often associated with higher film thicknesses than when using paints. Some of these lining can be applied in thicknesses of several milimetres, some may be several centimetres thick. Types of organic lining that are mostly used are tar coating, asphalt, various plastic coatings, bitumen, grease-like coatings, tapes, etc. Steam Power Plant Paiton Unit 7 & 8 3 is the one of power plant that provides electricity to the area of Java and Bali. To provide electricity for the area of Java and Bali, Steam Power Plant Paiton Unit 7 & 8 and 3 are equipped with devices that support the overall system. Existing equipment that has both technical specifications and functions and generally work systematically either mechanical, physical, or chemical. One of these devices is circulating water line of condenser that used as cooler device. The rubber lining applied inside the circulating water line to prevent corrosion. However, rubber lining cannot always prevent corrosion properly. Within some period, the rubber lining will be damaged due to flaking on the overlap caused by fluid that passes through the line at high speed. Very important to conduct this research about the influence of flow speed and time period on rubber lining damage in circulating water line of condenser to optimize the rubber lining as corrosion protection in circulating water line and prevents damage either technically and economically. THEORETICAL BACKGROUND Condenser Steam power plants utilize a surface condenser cooled by water circulating through tubes. The steam which was used to turn the turbine is exhausted into the condenser. The steam is therefore condensed as it comes in contact with the cool tubes full of circulating water. This condensed steam is withdrawn from the bottom of the surface condenser. The condensed steam is now water, commonly referred to as condensate water. Rubber Lining Rubber lining is the one of lining that made by rubber. Rubber usually used for protection of

2 both the interior of tanks for acids and alkalis and of the exterior of pipes in the splashzone. The coating takes place in the shops where the steel is first blast cleaned and then applied with a tie coat primer. This primer acts like a glue for the rubber lining itself, which is applied as wallpaper. The rubber is cured (vulcanized) under pressure and hot air (approximately o C) in a kind of oven, a so-called autoclave. The vulcanization may take one hour or more. Rubber Lining Damage Rubber lining damage in this research, is the damage on the surface of rubber lining due to friction between fluid flow and the surface of rubber lining continuously. Types of rubber lining damage are. Cracking is fissure that are more heavy and deeper than checking (the coatings breaks down due to cracking in the surface). To find the scratches on the surface of rubber lining, conducted direct inspections in the location that has been determined and were photographed using a camera. Inspection method that has been used is the visual inspection method. The number of scratches expressed in percentages (%). Blister is filled bumps that look like bubbles on the rubber lining. To find the blisters on the surface of rubber lining, conducted direct inspections in the location that has been determined and were photographed using a camera. Inspection method that has been used is the visual inspection method. The number of blisters expressed in percentages (%). Overlap is a break or hole between rubber lining joint.to find the overlap damage on the surface of rubber lining and rubber joint, conducted direct inspections in the location that has been determined and were photographed using a camera. Inspection method that has been used is the visual inspection method. The overlapdamage expressed in percentages (%). Thickness changes, to measure thickness changes of rubber lining, conducted direct inspections in the location that has been determined and measured the thickness of rubber lining using electronic film thickness gauge [Figure 1]. Inspection method that has been used is the thickness test. The number thickness changes expressed in percentages (%). Pinhole is small craters, holes or pits in the coating film.to find the pinholes on the surface of rubber lining, conducted direct inspections in the location that has been determined and detected the pinholes using Holiday Tester (High Voltage Spark Tester) [Figure 7]. Inspection method that has been used is the holiday test. The number of pinholes expressed in percentages (%). To measure the rubber lining damage in this research is by comparing the condition of rubber lining before damaged with condition when fluid passes the surface of rubber lining within certain flow speed and time. Rubber lining damage in this study, expressed in percent (%). Electronic Film Thickness Gauge Electronic Film Thickness Gauge is an electronic device used for measuring the coating film thickness. To measure the thickness of rubber lining, using PosiTector Figure 1: Electronic Film Thickness Gauge(type: PosiTector 6000) Figure 2: Types of testing probes that used (from left to right: for measuring film thickness on the curved surface and using µm-mm unit, for measuring film thickness on the plane and using mm unit, for measuring film thickness on the plane surface and using µm unit) High Voltage Spark Tester Holiday tester (High Voltage Spark Tester) is an electronic device used for locating discontinuities in a non-conductive coating applied to a conductive substrate. The instrument can either be connected to the mains or have rechargeable batteries. It is operate at voltages from approximately 1000 to volt, depending on the instrument. The instrument is equipped with a testing probe, either in the shape of a steel brush or a rubber-coated probe. This method is commonly used for coatings with a thickness of 500 μm or more. When a holiday is detected, a signal lamp within the exploring electrode flashes or an audible sound is produced.

3 RESULTS Pipe Diameter Variation Time Period : 1 Year Temperature : 45 o C Flow (Q) : 8.52 m 3 /s Fluid Density : kg/m 3 Table 2. Scratch Percentage on Rubber Lining Figure 3: Holiday Tester (High Voltage Spark Tester). Before the spark testing process is started, these conditions must be fulfilled. The top coat must not be electrically conductive. The paint must be fully cured. The surface must be clean (free of grease, oil, and dirt). The paint film thickness should normally be above 500 μm, but also lower thicknesses can be holiday tested. more scratches on rubber lining. This is also shown in figure below. Table 1. Suggested voltages for high voltage spark testing, listed in the standard ASTM D 5162 Figure 4. Flow Speed vs Scratch RESEARCH PROCEDURE The setting of this research that based on the objectives, using quantitative descriptive method, where this study sought to describe the influence of flow speed on rubber lining damage in circulating water line of condenser PT. IPMOMI (Steam Power Plant Paiton Unit 7 & 8). The research procedures include thickness test, holiday test, and direct inspection in the location using camera. But, we found an oddity between Inner Loop Pipe and Manhole. It is due to different flow regimes. In fact, turbulent flow occurs more often in manhole than in Inner Loop Pipe. This case can be proved by calculating Reynolds number. Inner Loop Pipe Re = ρvd μ = 1015,95!". 1,62!. 2,59 m!!! 6,47 10!! Pa. s = 6,59 10! Manhole Re = ρvd μ = 1015,95!". 18,69!. 0,76 m!!! 6,47 10!! Pa. s = 22,3 10! Re number of manhole is greater than Re number of Inner Loop Pipe. This proves that turbulent flow occurs more often in manhole. Consequently, based on standard measurement in this research (page 32), the scratch value in Inner Loop Pipe is greater than scratch value in Manhole. Table 3. Blister Percentage on Rubber Lining

4 more blisters on rubber lining. This is also shown in figure below. Table 4. Thickness Changes Percentage on Rubber Lining higher the thickness changes on rubber lining. This is also shown in figure below. Figure 5. Flow Speed vs Blister But, we found an oddity between Manhole and Discharge Pipe. It is due to different time period of fluid through those pipes. In fact, the fluid flow through the discharge pipe only once per 8 hours while manhole always passed by fluid flow in a year. Consequently, blister value in manhole is greater than discharge pipe. Table 4. Overlap Percentage on Rubber Lining more overlaps on rubber lining. This is also shown in figure below. Figure 7. Flow Speed vs Thickness Changes But, we found an oddity between Inner Loop Pipe and Manhole. It is due to dramatic flow speed difference. So, the erosion on rubber lining surface more often occurs in Manhole that cause the rubber lining thickness decreased. Consequently, thickness changes value in manhole is greater than Inner Loop Pipe. Table 5. Pinhole Percentage on Rubber Lining more pinholes on rubber lining. This is also shown in figure below. Figure 6. Flow Speed vs Overlap But, we found an oddity between Manhole and Discharge Pipe. It is due to different time period of fluid through those pipes. In fact, the fluid flow through the discharge pipe only once per 8 hours while manhole always passed by fluid flow in a year. Consequently, overlap value in manhole is greater than discharge pipe. Figure 8. Flow Speed vs Pinhole

5 Table 6. Rubber Damage Rate (Total) Due to Flow Speed Table 8. Blister Percentage on Rubber Lining From the figure above, we can conclude that the more severe the rubber lining damage. This is also shown in figure below. line, the more blisters on rubber lining. This is also shown in figure below. Figure 9. Flow Speed vs Rubber Damage Rate (Total) Time Period Variation Location : Discharge Pipe Flow Speed : m/s Flow (Q) : 8.52 m 3 /s Temperature : 45 o C Fluid Density : kg/m 3 Table 7. Scratch Percentage on Rubber Lining Figure 11. Time Period vs Blister But, we found an oddity between 9 and 12 months. It is due to the shutdown process of circulating water. Within 9-12 months, the discharge pipe has rarely passed by the fluid flow. So, the presence of blisters in 9 months not too different from 12 months. Table 9. Overlap Percentage on Rubber Lining line, the more scratches on rubber lining. This is also shown in figure below. line, the more overlaps on rubber lining. This is also shown in figure below. Figure 10. Time Period vs Scratch Figure 12. Time Period vs Overlap But, we found an oddity between 6 and 9 months. It is due to the process of circulating water. Within 6-9 months, the discharge pipe has rarely passed by

6 the fluid flow. So, the presence of blisters in 6 months not too different from 9 months. Table 10. Thickness Changes on Rubber Lining But, we found an oddity between 9 and 12 months. It is due to the shutdown process of circulating water. Within 9-12 months, the discharge pipe has rarely passed by the fluid flow. So, the presence of pinholes in 9 months not too different from 12 months. Table 12. Rubber Damage Rate (Total) Due to Time Period line, the higher the thickness changes on rubber lining. This is also shown in figure below. From the figure above, we can conclude that the line, the more severe the rubber lining damage. Figure 13. Time Period vs Thickness Changes But, we found an oddity between 9 and 12 months. It is due to the minor damage, and that is overlap. The overlap causes the fluid entered the rubber lining joint so the fluid push the rubber lining which still attached to pipe until that rubber lining off from the pipe (rubber lining loss of adhesion) and the rubber lining go wasted to discharge canal. Finally, the fluid interact directly with the pipe causes the corrosion of the pipe and causing leakage. Table 11. Pinhole Percentage on Rubber Lining line, the more pinholes on rubber lining. This is also shown in figure below. Figure 14. Time Period vs Pinhole Figure 15. Time Period vs Rubber Damage Rate (Total) From the figure above, we can conclude that the line, the more severe the rubber lining damage. DATA ANALYSIS Data analysis in this study using Numbers application where the obtained data are presented in plot. The plot that made was the relationship between flow speed of fluid to the percentage of rubber lining damage and relationship between time period to the percentage of rubber lining damage. To calculate the flow velocity of fluid, using equation v =!!, where: v = speed of fluid (m/s) Q = flow rate (m 3 /s) A = pipe cross section area (m 2 ) to calculate Reynolds number (used to characterize different flow regimes within a similar fluid, such as laminar or turbulent flow), using equation, Re = ρvd μ = vd ν = QD νa where: D = diameter of pipe (m) Q = flow rate (m 3 /s) A = pipe cross-sectional area (m 2 ) v = speed of fluid (m/s) μ = dynamic viscosity of fluid (Pa.s) ν = kinematic viscosity (m 2 /s)

7 ρ = density of fluid (kg/m 3 ) For flow in a pipe diameter D, experimental observations show that for fully developed flow, laminar flow occurs when Re D < 2300 and turbulent flow occurs when Re D > In the interval between 2300 and 4000, laminar and turbulent flows are possible and are called transition flows, depending on other factors, such as pipe roughness and flow uniformity. CONCLUSIONS 1. Increase in flow speed and time period of fluid through the line will cause the rubber lining damage (total) more severe. Scratch The presence of scratches on the rubber lining surface caused by flow speed, turbulent flow, and time period. Increase in flow speed and time period, and more often turbulent flow occurs will cause the scratch value greater. Blister The presence of blisters on the rubber lining caused by flow speed, time period, and circulating water process. Increase in flow speed and time period will cause the blister value greater. The more often the fluid flow passes the line during circulating water process, the more blisters on rubber lining. Overlap The presence of overlap on the rubber lining caused by flow speed, time period, and circulating water process. Increase in flow speed and time period will cause the overlap value greater. The more often the fluid flow passes the line during circulating water process, the more overlaps on rubber lining. Thickness Changes Thickness changes on the rubber lining caused by flow speed, minor damage, and time period. Increase in flow speed and time period will cause the overlap value greater. The more often the minor damage occurs during circulating water process, the more severe the thickness changes on rubber lining. Pinhole The presence of pinholes on the rubber lining caused by flow speed, time period, and circulating water process. Increase in flow speed and time period will cause the pinhole value greater. The more often the fluid flow passes the line during circulating water process, the more pinholes on rubber lining. SUGGESTIONS 1. Conduct the inspection more intensive than usual to minimize the rubber lining damage. 2. Refining the piping design by reducing the difference in pipe diameter to minimize rubber lining damage (scratch, blister, overlap, thickness changes, and pinhole). 3. Reducing the rubber lining joint to minimize overlapping. REFERENCES Kjernsmo, Dag.,Kleven, Kjell. & Scheie, Jan Corrosion Protection: Inspector s Book of Reference. FROSIO. Carter, V. E Corrosion Testing for Metal Finishing. Butterworths. ASM International. Metals Handbook Ninth Edition Volume 13 Corrosion. Revie, Winston, R. & Uhlig, Herbert, H Corrosion and Corrosion Control 4 th Edition: An Introduction to Corrosion Science and Engineering. John Wiley and Sons, Inc. DOE Fundamentals Handbook Thermodynamics, Heat Transfer, And Fluid Flow (Volume 3). Washington, D.C: U.S Departement of Energy. Harsisto. & Anwar, Syaiful Failure Analysis of Cast Material 316 L of Sea Water Pump Impeller in the Petroleum Industries. JurnalKorosi, 18(1): Setia Nusa, M.N Korosi Erosi yang Mengakibatkan Rusaknya Flange Pipa Penyalur. Jurnal Korosi, 18(1): A. Neville, T. Hodgkies, J. T. Dallas. A Study of The Erosion-corrosion behavior of Engineering Steels for Marine Pumping Application. Wear, 186(187): Dooley, R. B. & Chexal, V. K. Flow-accelerated Corrosion of Pressure Vessels in Fosil Plants. International Journal of Pressure Vessels and Piping, 77(3): Uzelac, N.I., Willems, H.H. &Barbian, O.A. In- Line Inspection Tools for Crack Detection in Gas and Liquid Pipelines. Corrosion, (online), Paper No.88. Robinson, J. &Drews, T. Resolving Flowaccelerated Corrosion Problems in the Industrial Steam Plant. OnePetro, 3-7. Habib, K. Failure of Thin Films of Organic Coatings by Shearography: Novel Approach-1. The Journal of Corrosion Science and Engineering, (online), 10(34): Potter, Merle C. & Wiggert, David C Schaum s Outline Mekanika Fluida. Erlangga.

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