Nano Coating as an Alternative to Conventional Insulation for High Temperature Piping: Field Trial Qualification Test

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1 Original Research Article Nano Coating as an Alternative to Conventional Insulation for High Temperature Piping: Field Trial Qualification Test M. Hasbi A. Razak 1*, Amirah Che Zakaria 1, Sy Muhsin Sy A. Hamid 1 1 Materials and Corrosion Engineering, Engineering Department, PETRONAS Carigali Sdn. Bhd, PETRONAS Twin Towers, KLCC, Malaysia ABSTRACT *Corresponding author s phone no.: hasbi@petronas.com.my Date of submission: 26 th May 2015 Date of revision: 29 th July 2015 Date of acceptance: 5 th August 2015 A feasibility study was conducted on the application of a patented nano coating product as thermal insulation protection for high temperature piping as an alternative to conventional insulation. A field trial qualification test was conducted at an offshore gas platform on a 508 mm-diameter gas compression piping with skin temperature in the range of C. Three different coating thicknesses were tested to investigate and confirm the relationship between coating thickness and surface temperature. The condition of the piping was monitored regularly over a period of six (6) months via visual inspection, surface temperature checking and ultrasonic (UT) thickness measurement in order to determine its effectiveness as a thermal insulator. The findings from the field trial revealed that there was a temperature reduction in the range of thicknesses tested. However, the temperature reduction did not perform according to the manufacturer specifications. Keywords: Nano coating; thermal insulation; high temperature; temperature reduction. 1.0 INTRODUCTION Industries worldwide are currently shifting their focus towards nano technology, where many potential applications have been identified [1, 2, 3]. One such application is nano coating, which is a new type of insulation material in coating form with the materials size at the scale of atoms or molecules (10-9 m). This insulation technology limits the heat transfer through its layer and acts as a thin insulator which preserve the heat of fluids, and is safe for personnel touch according to Occupational Safety and Health Administration (OSHA). Conventional insulation has several disadvantages. It can lead to Corrosion Under Insulation (CUI). Another disadvantage of conventional insulation is in performing inspection and maintenance of piping systems. For example, in order to obtain reliable inspection results, insulation must be removed and replaced or re-installed, which can prove to be costly [4]. Many industries, such as the oil and gas sectors, are having problems with CUI [5, 6, 7], when conventional insulation is installed to high temperature piping systems. As an alternative method to eliminate CUI, a few industries in the oil and gas sector claimed to have successfully applied nano coating to replace conventional insulation. Furthermore, cost reductions can be attained due to a reduction in installation and periodical inspection maintenance costs. This leads to a reduced Life Cycle Cost (LCC) of the system throughout its operating life. The main objective of this paper is to investigate the effectiveness of a patented nano coating product (nano composite) which was selected from one manufacturer, in reducing the skin temperature 300

2 M. Hasbi A. Razak, Amirah Che Zakaria, Sy Muhsin Sy A. Hamid of hot piping systems, while performing visual inspection to assess the coating condition throughout the duration of the test and performing Ultrasonic Testing (UT) thickness gauging on designated locations. This paper does not discuss the nano coating manufacturing method and process, and product composition, as these information are proprietary to the manufacturer. 2.0 EXPERIMENTAL DETAILS 2.1 Test Panel UT Thickness Gauging Four (4) test plates with similar mock up defect sizes were prepared with the following detailed measurements (Figure 1). After blast cleaning the surface of each plate to SA 2.5, in accordance with the Society for Protective Coating (SSPC) specification, UT Thickness gauging was performed on each plate before and after applying the nano coating with different Dry Film Thicknesses (DFT) using UT CYGNUS 2 equipment. Figure 1. Test Plate with Mock up Notch Defects Dolly Pull Test To evaluate the adhesiveness of the coating, dolly pull tests were performed on the four (4) test plates with different coating thickness (Table 1), after curing time (i.e. 46 days after paint application). The dolly pull test was performed in accordance with ASTM D4541 [7] (Figure 2). Table 1. Coating Thickness on Test Plates Plate No. DFT (μm) Plate Plate Plate Plate

3 Nano Coating as an Alternative to Conventional Insulation for High Temperature Piping: Field Trial Qualification Test Figure 2. Pull Off Test using Elcometer Temperature Test Four (4) different coated test plates were exposed to a direct heat source (flame from burner) at the bottom. Temperature measurements were taken at the top (coated) and bottom (uncoated) surfaces. Three (3) different locations were identified on each of the coated and uncoated surfaces (Figure 3). The temperature of the entire uncoated surface was maintained at 100 C. Figure 3. Temperature Measurement Locations Note: Loc = Location 2.2 Field trial The field trial was conducted at an offshore gas platform on a gas compression piping, approximately 500mm in diameter with skin temperature between 95 to 100 C (Figure 4). 302

4 M. Hasbi A. Razak, Amirah Che Zakaria, Sy Muhsin Sy A. Hamid Figure 4. Selected Gas Compression Piping System Prior to Application. The pipe section was divided into 3 adjacent areas, at 2m length each with 3 different coating thicknesses i.e. 350, 500 and 700 μm (Figure 5). Area 1 (350 µm) Area 2 (500 µm) Area 3 (700 µm) Loc 1 Loc 2 Loc 3 Loc 4 Loc 5 Loc 6 Figure 5. Pipe Sections with Different Coating Thicknesses Note: Loc = Location The coating thicknesses were selected in order to achieve different surface temperatures as per manufacturer specifications (Table 2). Area Table 2. Coating Thickness Selection against Expected Temperature Reduction. Expected Average Surface Temperature / % Reduction Coating Thickness (μm) Remark Area 1 57 C (~40%) 350 Safe touch according to OSHA Area 2 47 C (~50%) 500 Intermediary Temperature Area 3 37 C (~60%) 700 Equivalent to human body temperature Each of the location identified i.e. location 1, 2, 3 etc. were further divided into 4 equidistant locations (Figure 6). The temperature of each of these locations were measured and averaged. 303

5 Nano Coating as an Alternative to Conventional Insulation for High Temperature Piping: Field Trial Qualification Test Figure 6. Temperature Monitoring Locations. The temperature measurements were taken via digital contact thermometer regularly over a 6 month period after curing time (45 days after paint application). 3.0 RESULTS AND DISCUSSION 3.1 Test Panel UT Thickness Gauging UT thickness gauging was able to be performed on top of nano coating even with DFT of 1000 μm at room temperature (Table 3). Nano coating need not be removed during offline inspection to perform UT thickness gauging. However, this may only be applicable to certain UT equipment. Table 3. UT Thickness Gauging Before and After Coating. Plate No. Thickness Before Coating (mm) Defect No. Thickness After Coating (mm) Defect No Plate Plate Plate Plate Dolly Pull Test Pull Test strength exceeds the SSPC Painting Manual and PETRONAS Technical Standards requirements which are a minimum of 200 psi and 300 psi respectivelytable 4). As the thickness of the coating increases, the strength of the coating decreases. This could be due to the development of inner stress within the coating layer as the thickness increases, which leads to a weakening of the bonding strength between the coating and the metal surface. As a result, mechanical properties such as adhesiveness decreases. 304

6 M. Hasbi A. Razak, Amirah Che Zakaria, Sy Muhsin Sy A. Hamid Plate No. DFT (μm) Table 4. Dolly Pull Test Results. Maximum Strength Before Failure (psi) Dolly 1 Dolly 2 Dolly 3 Dolly 4 Dolly 5 Average Plate ,300 1,100 1,400 1, Plate , Glue Failure Plate Plate 4 1, Glue Failure 400 Glue Failure Temperature Test There was a noticeable reduction in temperature on the coated surface for all coating thickness (Table 5). In general, there is a downward trend of temperature as the coating thickness increases. Table 5. Average Coated Surface Temperature of Different DFT. Plate No. Thickness (μm) LOC 1 ( C) LOC 2 ( C) LOC 3 ( C) Plate Plate Plate Plate Field Trial Visual Inspection The coating was visually inspected and was found to be in good condition throughout the duration of the testing period Surface Temperature Test The coating was applied via airless spray on 8 September 2012 and completed on 19 September The coating was allowed to cure for 45 days prior to conducting any inspection and testing. One (1) set of temperature readings was taken after 60 days and two (2) more sets of temperature readings were taken after 120 days upon completion of application. Table 6 and Figure 7 shows the average temperature of four (4) equidistant points on the surface of the pipe at each location compared with the expected temperature based on the manufacturer s specifications. Table 6. Temperature Readings at each Location of Different Coating Thicknesses. Skin temperature before application : C Description Days after coating application Area 1 (350 μm) Area 2 (500 μm) Area 3 (700 μm) Expected Temp. ( C) N/A

7 Temperature ( C) Nano Coating as an Alternative to Conventional Insulation for High Temperature Piping: Field Trial Qualification Test Expected % Temp. Reduction Actual Ave. Temp. at four equidistant points at each location ( C) ~40 ~50 ~60 > > > Ave. Temp. ( C) N/A Actual % Temp. Reduction N/A Expected vs. Actual Skin Temperature Expected Temp Actual Temp Ave. Skin Temp Before Coating Coating Thickness (μm) Figure 7. Expected vs. Actual Skin Temperature. A slight temperature reduction was observed as the coating thickness increased i.e. from 63.3 C at 350 μm to 58.4 C at 700 μm. However, this is deemed insignificant when compared with the expected temperature reductions as highlighted in the manufacturer s specifications. In the aspect of the coating homogeneity as well as coating texture, porosities might also contribute to small temperature reduction which need to be further investigated. It also appears that the coating materials do not exhibit low thermal conductivity property, and may not be effective as thermal insulators [9], therefore there is a need to evaluate the nano coating phases and crystalline structure. CONCLUSION The findings from the field trial revealed that the test results are not encouraging. The development of nano coating as thermal insulation protection should be continuously monitored as it has a lot of potential benefits. However, it may require some time for this technology to reach maturity. 306

8 M. Hasbi A. Razak, Amirah Che Zakaria, Sy Muhsin Sy A. Hamid ACKNOWLEDGEMENT The authors would like to thank PETRONAS Carigali Sdn. Bhd. (PCSB) for their continuous support in the study and field trial of this technology. REFERENCES 1. Mokhatab, S., Fresky, M. A., Islam, M. R., Applications of Nanotechnology in Oil and Gas E&P, Society of Petroleum Engineers, Bell, Matthew R.G., A Case for Nanomaterials in the Oil & Gas Exploration & Production Business, International Congress of Nanotechnology (ICNT), San Francisco, California, USA, November 7-10, Monfrared, S., Applications of Nanotechnology in the Oil and Gas Industry, Technical Communication , Norman, Oklahoma, USA. 4. Anderson, S. A., Out of Sight, Out of Mind?, Hydrocarbon Engineering, August Hanratty, T., Corrosion Under Insulation - The Hidden Problem, Hydrocarbon Asia Apr-Jun 2012, p Fruge. D., Bishop. K, Corrosion Under Insulation, 20 th Ethylene Producers Conference, New Orleans, Louisiana, USA, April 6-10, Lettich. M., Is There A Cure For Corrosion Under Insulation?, Insulation Outlook, November ASTM International, Standard Test Method for Pull-Off Strength of Coatings Using Portable Adhesion Testers, ASTM D e1, Garber-Slaght. R., Craven. C, Technical Report # Product Test: Nansulate and Super Therm, Cold Climate Housing Research Center, August