An Examination of Interfering Factors in the ASTM D-1838 Copper Strip Test

Transcription

1 GPA Research Report RR-190 GPA RESEARCH PROJECT No An Examination of Interfering Factors in the ASTM D-1838 Copper Strip Test ASRL # P.D. Clark and K.L. Lesage, Alberta Sulphur Research Ltd., c/o Department of Chemistry, The University of Calgary, Calgary, Alberta, Canada March 2006

2 II. FOREWORD This project continues GPA s research program on trace specie impact on the Copper Strip Test (ASTM D-1838). This continuation of Project 982 and was designed to verify and validate the Copper Strip Test for LP Gas. This work was supported with funding from the Propane Education and Research Council. Based on the results presented in this report and the previous work on this project, the following conclusions can be made: The Copper Strip Test accurately detects corrosion for several containments commonly found in LP Gas. Even with the addition of water as required by ASTM D-1838, Carbonyl Sulfide does not reliably produce a corrosive test coupon. Use of the Copper Strip Test requires that one rigorously follow the test procedure, including the use of the proper apparatus and methods. The findings of previous studies which did not precisely follow ASTM D-1838 are therefore suspect. Dan McCartney, Coordinator GPA Project 982 Arild Wilson, Sub-group #1 Chairman David Bergman, Section F Chairman i

3 III. DISCLAIMER AND COPYRIGHT NOTICE GPA publications necessarily address problems of a general nature and may be used by anyone desiring to do so. Every effort has been made by GPA to assure accuracy and reliability of the information contained in its publications. With respect to particular circumstances, local, state, and federal laws and regulations should be reviewed. It is not the intent of GPA to assume the duties of employers, manufacturers, or suppliers to warn and properly train employees, or others exposed, concerning health and safety risks or precautions. GPA makes no representation, warranty, or guarantee in connection with this publication and hereby expressly disclaims any liability or responsibility for loss or damage resulting from its use or for the violation of any federal, state, or municipal regulation with which this publication may conflict, or any infringement of letters of patent regarding apparatus, equipment, or method so covered. Entire contents Copyright 2006 by Gas Processor s Association, all rights reserved. ii

4 IV. TABLE OF CONTENTS II. FOREWORD i III. DISCLAIMER AND COPYRIGHT NOTICE ii IV. TABLE OF CONTENTS iii V. LIST OF TABLES... iv VI. LIST OF FIGURES iv VII. INTRODUCTION.. 1 VIII. OVERALL RESULTS AND CONCLUSIONS 1 IX. DISCUSSION OF RESULTS..2 Test Matrix and Results.2 Interpretation and Conclusions from Individual Sets of Tests..4 Blank tests.4 Test with Hydrogen Sulfide (H 2 S) 4 Tests with Elemental Sulfur (S 8 )...4 Tests with Carbonyl Sulfide (COS)...5 Tests with Oxygen (O 2 ).5 Tests with carbon dioxide (CO 2 ) 5 Test with a Combination of H 2 S and O 2 5 Test with a Combination of H 2 S and CO 2.6 Test with a Combination of COS and O 2..6 X. EXPERIMENTAL DETAIL..7 XI. REFERENCES.. 9 XII. APPENDIX A-1. Data tables 10 A-2. Figures..14 A-3. Reaction Schemes for Interaction of Trace Contaminants with Copper Surfaces.41 iii

5 V. LIST OF TABLES Table 1. Matrix of Tests...3 Table 2. Results of Copper Strip Tests..3 Appendix A1: Gas composition of propane mixtures pre and post copper strip testing Table A1-1. Propane + H 2 S...10 Table A1-2. Propane + COS Table A1-3. Propane + O Table A1-4. Propane + CO Table A1-5. Propane + H 2 S and O Table A1-6. Propane + H 2 S and CO Table A1-7. Propane + COS and O VII. LIST OF FIGURES Figure 1. Reproduction of the ASTM Copper Strip Corrosion Standards Plaque..14 Figure 2. Instrument Propane Blank...15 Figure 3. H 2 S 5 ppmw in Propane...16 Figure 4. H 2 S 10 ppmw in Propane. 17 Figure 5. H 2 S 20 ppmw in Propane. 18 Figure 6. S 8 5 ppmw in Propane..19 Figure 7. S 8 10 ppmw in Propane 20 Figure 8. S 8 20 ppmw in Propane 21 Figure 9. COS 5 ppmw in Propane..22 Figure 10. COS 10 ppmw in Propane..23 Figure 11. COS 20 ppmw in Propane..24 Figure 12. COS 100 ppmw in Propane 25 Figure 13. O 2 50 ppmw in Propane.26 Figure 14. O ppmw in Propane...27 Figure 15. O ppmw in Propane.28 Figure 16. CO 2 10 ppmw in Propane..29 Figure 17. CO ppmw in Propane 30 Figure 18. CO ppmw in Propane..31 Figure 19. H 2 S 5 ppmw + O ppmw in Propane...32 Figure 20. H 2 S 5 ppmw + O ppmw in Propane.33 Figure 21. H 2 S 10 ppmw + O ppmw in Propane...34 Figure 22. H 2 S 5 ppmw + CO 2 10 ppmw in Propane...35 Figure 23. H 2 S 5 ppmw + CO ppmw in Propane.36 Figure 24. H 2 S 10 ppmw + CO 2 10 ppmw in Propane.37 Figure 25. COS 10 ppmw + O ppmw in Propane 38 Figure 26. COS 10 ppmw + O ppmw in Propane..39 Figure 27. COS 100 ppmw + O ppmw in Propane 40 iv

6 VII. INTRODUCTION ASTM D 1838 is a test procedure used to evaluate the potential corrosiveness of liquefied petroleum gas containing trace impurity components towards copper. In summary, the test involves immersion of a polished copper strip in the LPG in question at 100ºF (37.8ºC) for 1 hour and then comparison of the appearance of the strip to a set of commercial standards prepared for use as part of the ASTM procedure. The standards are differentiated into four categories (1 4) with sub-classifications of 1a - 1b, 2a 2e, 3a 3b and 4a 4c. The categories 1 4 represent slight tarnish, moderate tarnish, dark tarnish and corrosion respectively and the visual appearance of the categories ranges from an off-color copper metal for 1, a range of pinks, green/lavender and brassy gold colors for 2, magenta with over-casts of red and green for 3 and generally dark grays and blacks for 4. The D-ASTM 1838 procedure recognizes the general difficulty of differentiating some of the possible test results by not offering definitive guidelines for absolute assignment of a particular classification within each class. A review of the literature (refs.) shows that it is generally accepted that hydrogen sulfide (H 2 S) and elemental sulfur (S 8 ), even at low levels (1 20 ppmw), result in corrosion of the copper such that LPG containing these materials will result in 2c 4c results. Carbonyl sulfide (COS) has been shown not to tarnish copper within the framework of ASTM D-1838, even up to concentrations of 100 ppmw. However, hydrolysis or oxidation of COS may result in production of H 2 S and S 8 respectively, thus leading to field observations that LPG containing COS can fail the copper strip test if air or water contaminants are introduced at a later date. VIII. OVERALL RESULTS AND CONCLUSIONS A series of ASTM D-1838 copper strip corrosion tests was performed using propane as the base hydrocarbon containing various contaminant species, namely H 2 S, S 8, COS, CO 2 and O 2. In some cases, a combination of these contaminants was investigated. The concentrations of these components were chosen to meet the levels expected in commercial situations. H 2 S and S 8 were found to result in test failures at lower levels of 5 and 10 ppmw respectively. H 2 S resulted in multi-colored green-pink-lavender copper strips at 5 ppmw and dark grey-black strips > 10 ppmw. S 8 produced a grey-black copper strip at 10 ppmw or greater concentration. Possibly, a very thin grayish film may have been present using 5 ppmw S 8 but, overall, these tests were judged to be 1(a). The very weak dark film using 5 ppmw S 8 was not visible in the photographic records made for this project (see Appendix A-2). 1

7 COS, CO 2 and O 2 did not produce discoloration of the copper strips at < 100 ppmw concentration, but some discoloration (patchy orange) was observed for COS at 100 ppmw. A greenish tinge was observed for CO 2 at high levels but this discoloration was observer dependent and, again, was not visible in photographs (Appendix A-2). A combination of H 2 S and O 2` results in consumption of the H 2 S producing copper strips similar in appearance to tests with S 8 alone. This observation was made when only 10 ppmw H 2 S was present in the combined contaminant mixture. In general, a combined test using H 2 S and CO 2 resulted in copper strips similar in appearance to those obtained without CO 2. The exception to these observations was when ca ppmw CO 2 was present in combination with H 2 S. In this case the multi-color strips produced by H 2 S alone were replaced by an even dark layer on copper strip. Tests using a combination of COS and O 2 gave results very similar to those without O 2 until 1250 ppmw of O 2 was present. In this case, the test strips could clearly be designated as fails at the 3(a b) category. IX. DISCUSSION AND RESULTS Test Matrix and Results The proposed matrix of tests is given in Table 1 and the actual test conditions and result classification for each test are given in Table 2. Note that the very small quantities of sulfur compounds and trace contaminants shown as target concentrations in Table 1 were not achieved precisely because of the experimental limitations in introducing ppm quantities of sulfur compounds and contaminants to liquid propane. Classification of the test results according to the ASTM standards is subjective and open to observer bias. Thus, the determinations given in Table 2 contain the element of observer judgment. The reader can make his/her own evaluation by consulting the electronic files and photographic records provided with this report. 2

8 Table 1. Matrix of Tests a Propane Concentration (ppmw) b Contaminant Blank H 2 S S COS O CO H 2 S+O H 2 S+CO COS+O a. All tests were conducted according to ASTM D 1838 b. Contaminants quantities may vary by +/ - 25% Table 2 Results of Copper Strip Tests The results and conditions for the tests are recorded in Table 2, Figures 1 27 in Appendix A-2) and Tables A1-1 A1-7 in Appendix A1. Contaminant Concentrations (ppmw) and Results A. Blank None None 1a 1a B. H 2 S b 3b 3b 3b 4a 4a C. S a 1a 4a 4a 4a 4a D. COS a 1a 1a a 1a 1b / 3a E. O a a a 1a 1a F. CO a a 1a 1a 1a G. H 2 S O b 3b 3b 3b 4a 4a H. H 2 S CO b 3b 4a 4a 3b 3b I. COS O a 1a 1a 1a 3a / 3b 3a / 3b 3

9 Interpretation and Conclusions from Individual Sets of Tests As already stated, the reader may wish to consult the electronic files and photographic records provided with this report as assignment of the actual copper strips from each test condition is subject to observer bias. Blank tests. Observation of 1(a) results for tests with no contaminants validates that the experimental procedures of ASTM D-1838 were followed successfully and that any small amounts O 2 or CO 2 that are not purged from the apparatus do not cause a fail result. This result confirms that ASTM D-1838 does give a null result when its procedures are followed. Tests with hydrogen sulfide (H 2 S) A nominal concentration of 5 ppmw H 2 S in propane results in a 3(b) appearance and 4(a) when the H 2 S concentration was increased to 20 ppmw. The blue, green, lavender and pink striations of the 3(b) results are likely due to films of copper (I) and copper (II) sulfides lain over the metallic sheen of the copper surface. The darker coloration typical of the 4(a) result could be the product of copper corrosion by a combination of reactions involving S 8 as S 8 can be formed by the oxidation of H 2 S by the primary corrosion product copper (II) sulfide (see Appendix A-3) for schemes summarizing the overall chemistry). Gas analyses from these tests (Table A1-1)showed that with < 20 ppmw H 2 S in the initial charge, all of it was consumed by reaction with either the copper strip or was adsorbed on the walls of the apparatus. Some residual H 2 S was observed when the initial amount was 20 ppmw. The detection of small amounts of O 2 at the conclusion of the test, when none had been present at the beginning of a test, may stem from O 2 being desorbed from the walls of the apparatus into the propane during the test or by contamination with air during sampling. Tests with Elemental Sulfur (S 8 ) A 4(a) result was obtained with 10 ppmw or greater amount of S 8 dissolved in propane but interpretation of the 5 ppmw tests is more difficult. A very slight darkening of the copper strip was observed with 5 ppmw but it was difficult to assign the strips to any of the standards. S 8 appears to form black copper (II) sulfide as the only product thus the degree of darkening of the strip is homogeneous and dependent on the amount of S 8 in the system. 5 ppmw of S 8 appears to be near the level at which a fail copper strip test is produced by ASTM D-1838 but it seems that the strip appearances step from 1(a) directly to 4(a) as the concentration of S 8 increases. 4

10 Tests with Carbonyl Sulfide (COS) COS had no tarnish effect on copper up to concentration of 20 ppmw but a slight discoloration was observed for tests conducted with 100 ppmw. The 100 ppmw tests might be interpreted as either 1(b) or 3(a). These results show that COS does not hydrolyze to H 2 S under the conditions of ASTM D-1838 despite the presence of free water in the test. Even if the 100 ppmw test is judged to be 3(a) (an orange discoloration), the absence of the classic multicolor striations observed with small amounts of H 2 S offers further evidence that COS is not hydrolyzed rapidly to H 2 S under the conditions employed with ASTM-D1838. The gas analysis data (Table A1-2) show that little or no COS was consumed when the initial quantity was 20 ppmw or less, but the reduction in COS noted for the 100 ppmw experiment is in agreement with the copper strip appearance change observed at this level of COS. Tests with Oxygen (O 2 ) The background effect of O 2 is of interest because copper (II) oxide is black. However, incorporation of O 2 in the ppmw range did not produce a positive test illustrating that O 2 does not corrode copper over the time-frame of the test. It is unclear from the gas analysis data (Table A1-3) whether O 2 was consumed in any of the experiments with added O 2. Thus, the reductions observed at the highest added level could simply be due to adsorption onto the test cylinder surfaces. Tests with Carbon Dioxide Tests using a CO 2 range of 10 ca ppmw yielded 1(a) tests in all cases although at the highest level a general greening of the copper may have been apparent (observer dependent, but not recorded on the photographs). Since it is well known that exposure of copper to the atmosphere will lead to a green color over prolonged periods, it is concluded that the timeframe and conditions of ASTM D-1838 do not duplicate long term environmental exposure of copper to the atmosphere. The gas analysis data (Table A1-4) reveal that some CO 2 was consumed when the propane was charged with ca ppmw thus offering an explanation for the eye-only observation of a green tinge. Tests with a Combination of H 2 S and O 2 Since it is well known that O 2 converts H 2 S to S 8, a copper strip test with a combination of the two materials may yield corrosion patterns more reminiscent of sulfur. Examination of Table 2 shows that, as expected, the combination of H 2 S and O 2 results in 5

11 failing tests [3(b)] for low H 2 S concentrations (4-5 ppmw) and 4(a) for 12 ppmw H 2 S. Interestingly, the 12 ppmw test was more similar in appearance to the corresponding 10 ppmw S 8 test than to the 10 ppmw H 2 S test (with no added O 2 ) in that a generally even, dark discoloration was observed. Inspection of the gas data collected from these tests (Table A1-5) show that all of the H 2 S was consumed during the one hour period as was the case for H 2 S tests with up to 10 ppmw H 2 S (no air). However, since O 2 levels also decrease, this observation is in accord with its consumption by reaction with H 2 S. H 2 S can also be moved from the propane by reaction with copper or adsorption onto the test apparatus surfaces. Tests with a combination of H 2 S and CO 2 A test with 4.6 ppmw H 2 S and 9 ppmw CO 2 resulted in a 3(b) result with similar appearance to the equivalent test without CO 2. Likewise tests with 9 and 13 ppmw H 2 S and CO 2 yielded 3(b) results with similar appearances to the test without CO 2. However, the test employing 5 and 128 ppmw H 2 S and CO 2 respectively yielded a 4(a) result. In particular, the appearance of these strips was quite different to the 3(b) multi-colored appearances of the 5 ppmw H 2 S tests without CO 2. These results lead to the conclusion that CO 2 at > 100 ppmw will result in a change in appearance of the copper strip, most probably as a result of formation of a carbonate film at the copper surface. Gas analysis data (Table A1-6) show that all H 2 S was consumed and CO 2 is also absorbed on copper surfaces. Tests with a Combination of COS and O 2 One possible outcome of these tests was that COS would be oxidized to S 8 thus causing a fail test. With ca. 10 ppmw COS and either 74 or ca ppmw O 2 only minimal discoloration of the test strip was observed such that the result might be classified as 1(a), possibly 1(b). However, when 100 ppmw COS was present with 1250 ppmw O 2, the strips were discolored with classification as 3(a b). Oxidation of COS would yield both CO 2 and S 8 suggesting, perhaps, that a dark coloration would have been observed. Since this is not the case, it can be concluded that the oxidation of COS is slow and, most likely, follows a complex pathway which does yield S 8 as a prime product. Interestingly, the gas analysis data (Table A1-7) indicate that very little of the COS was reacted, even when quite high levels of O 2 were present. However, it appears that a considerable quantity of O 2 was absorbed onto the Copper Strip Vessel (CSV) and copper surfaces. Thus, the fail test observed with 100 ppmw COS may result from a complex combination of species arising from co-absorption of both COS and O 2. 6

12 X. EXPERIMENTAL DETAIL Overall Procedure: The basic procedures outlined in ASTM D-1838 were followed rigorously with deviations described below being employed to add the required contaminants. Apparatus and Materials: All experiments were conducted in a copper strip vessel using copper strips which met the specifications for the ASTM D-1838 procedure (Koehler Instruments). Sulfur free, liquid propane (Instrument Grade) was supplied by Praxair. The propane purity was validated by gas chromatography fitted with a thermal conductivity detector (detection limits: O 2 < 3 ppmw ; CO 2 < 4 ppmw) and with a pulsed flame photometric detector for sulfur compounds (COS, H 2 S, CS 2, MeSH, detection limit < 1 ppmw). In most experiments, trace contaminates were added to propane contained in a 500 ml SS charge cylinder. The exact composition of the propane was analyzed by GC prior to purging and filling a CSV. For the binary contaminate experiments (e.g. H 2 S and O 2 ), one contaminate was added to the charge cylinder and the other was introduced separately into the CSV just prior to propane introduction. In this manner the binary composition was created at the start of the test. In the case of the experiments utilizing S 8, the required amount of sulfur was added as a hexane solution to each individual CSV which was then charged with propane. The specific details relating to each experiment will be discussed separately. A GC sampling system was utilized that allowed for removal of a liquid propane sample into a 250 μl sampling loop at 212ºF (100 o C). A pneumatic valve then injected the contents of the sample loop into the gas chromatograph. Gas analysis was performed on the propane in the charge cylinder prior to the start of the test as well as on the propane in the CSV at the conclusion of the test. The wetted parts of the test system were 316 SS with fused silica and nylon transfer lines. Blank Tests: Blank tests were necessary to verify the purity of the propane, the cleanliness of the apparatus and the analytical methodology. The blank test consisted of filling the charge cylinder with propane and performing the ASTM D-1838 test as a propane sample. Gas analyses were performed on the propane that was loaded into the charge cylinder as well the propane in the CSV s at the conclusion of the test. Tests with H 2 S: In these tests the charge cylinder was flushed with pure H 2 S gas. Liquid propane was then introduced and the charge cylinder to fill it to capacity. Due to the high solubility of H 2 S in liquid propane the resulting mixture had an H 2 S concentration > 100 ppmw. The required concentration was prepared by venting a given weight from the charge cylinder and then re-filling with more propane. The exact concentration was verified by gas chromatography prior to the start of the copper strip test. Tests with S 8 : In these tests a solution of S 8 (re-crystallized from toluene) in hexanes was prepared and added to the individual CSV s. Each CSV was determined to contain 60 +/- 7

13 2 g of propane when was filled with propane. Therefore, to perform a 20 ppmw S 8 test a solution of 1.2 mg/ml S 8 in hexanes was prepared. One ml of this solution was added to the CSV after water wetting and prior to filling with propane. It was assumed that the act of filling the CSV mixed the hexane solution with the liquid propane. No initial analytical determination of the S 8 content was made. At the conclusion of the test the contents of the CSV was collected to determine the residual S 8 content. Tests with COS: These tests were performed in a manner similar to that described for H 2 S. I.e., the charge cylinder was flushed with pure COS gas. The COS was also very soluble in the liquid propane and subsequent venting and dilution of the charge cylinder contents was necessary. Tests with O 2 : The tests performed with O 2 as an impurity were unique with respect to the fact that O 2 gas has a very limited solubility in liquid propane. Initially it was thought that the higher concentration of O 2 in liquid propane were unattainable at ambient temperatures. It was found, however, that the O 2 concentration could be increased substantially by maintaining an overpressure of pure O 2 over the liquid propane in the charge cylinder. It was realized that some of this dissolved O 2 would be lost after charging the CSV but each concentration was verified before the start of the test. Tests with CO 2 : For tests performed with CO 2 as an impurity the charge cylinder was initially filled with propane. A small amount of CO 2 gas was added via the lower valve on the charge cylinder. (CO 2 delivery pressure = 800 psig). Analysis of the charge cylinder contents showed that an equilibrium CO 2 concentration was established rapidly. The CO 2 was found to be quite soluble in liquid propane and the overpressure in the charge cylinder, even at 1000 ppmw, was negligible. Tests with H 2 S + O 2 : For these tests a saturated solution of H 2 S in hexanes was prepared. It was found that the solution as prepared was not stable and lost H 2 S rapidly perhaps as oxidation to S 8. Therefore, a freshly saturated hexane solution was prepared and 20 ml aliquots were sealed in glass ampoules. On a given day of testing an ampoule was opened and decanted into a vial. It was found that 0.25 or 0.50 ml of the solution gave a 5 or 10 ppmw H 2 S concentration in the CSV. The concentration was analyzed at the beginning of the day to verify that the H 2 S initial concentration was correct. The charge cylinder was prepared with the required O 2 concentration as per the O 2 tests and its concentration was also verified by GC. The correct amount of H 2 S in hexane (0.25 or 0.50 ml) was added to the water wet CSV which was then sealed with a polished copper strip. The O 2 in propane was added from the charge cylinder making the assumption that adequate mixing was accomplished during the filling operation. At the conclusion of the test the liquid propane in the CSV was analyzed. Another aliquot of H 2 S in hexane (0.25 or 0.50 ml) was added to a dry CSV and filled with propane to again verify the H 2 S concentration (final). The average value of the initial and final H 2 S result was the value that was reported for that particular test. 8

14 Tests with H 2 S + CO 2 : These tests were performed in an analogous manner to the H 2 S- O 2 tests with CO 2 being substituted for O 2 in the charge cylinder. The same ampoules of H 2 S in hexanes were used for these tests. Tests with COS + O 2 : For these tests a solution of COS in hexanes was prepared and sealed in ampoules. A fresh ampoule was used daily in a manner similar to that described for H 2 S. It was found that COS was very soluble in the hexanes. One hundred microliters or 1 ml of solution gave COS concentrations of 10 or 100 ppmw respectively in the CSV s. Again the COS concentration was checked at the beginning (initial) and at the end (final) of the actual copper strip test as separate determinations. A significant portion of the initial COS remained in the CSV s at the conclusion of the tests. This result indicates that the rate of COS oxidation is slow, relative to the time scale of the ASTM D1838 copper strip test. XI. REFERENCES Ferm, R.J. The Chemistry of Carbonyl Sulfide. Chem Rev. 1957, 57, 621. Svoronos, P.D.N.; Bruno T.J. Carbonyl Sulfide: A Review of the Chemistry and Properties. Ind. Eng.Chem. Res. 2002, 41, Chalk, G. MetroGas, Inc., Denver, CO. Personal Communication, Andersen, W. C.; Bruno, T.J. Kinetics of Carbonyl Sulfide Hydrolisis. 1. Catalyzed and Uncatalyzed Reactions in Mixtures of Water + Propane. Ind. Eng. Chem. Res. 2003, 42, Thompson, H.W.; Kearton, C.F.; Lamb, S.A. The Kinetics of the Reaction between Carbonyl Sulphide and Water. J. Chem. Soc. 1935,

15 XII. APPENDIX A-1. Data Tables (Note: all CSV data were obtained at the conclusion of the tests) TABLE A 1-1: Propane + H 2 S Gas Composition (ppmw in Propane) Nominal PPMW H2S Sample O2 CO2 COS H2S 5 Charge Cylinder(1) < 3 < 4 < CSV-1 31 < 4 < 1 < 1 CSV-2 35 < 4 < 1 < 1 10 Charge Cylinder(1) < 3 < 4 < 1 11 CSV < 1 < 1 CSV-2 20 < 4 < 1 < 1 20 Charge Cylinder(1) < 3 < 4 < CSV-1 20 < 4 < CSV-2 15 < 4 < (1) - Average of 3 or more Determinations TABLE A 1-2: Propane + COS Gas Composition (ppmw in Propane) Nominal PPMW COS Sample O 2 CO 2 COS H 2 S 5 Charge Cylinder (1) < 3 < < 1 CSV-1 3 < < 1 CSV < < 1 10 Charge Cylinder (1) < 3 < < 1 CSV-1 < 3 < < 1 CSV-2 41 < < 1 20 Charge Cylinder (1) < 3 < < 1 CSV-1 < 3 < < 1 CSV-2 3 < < Charge Cylinder (1) < 3 < < 1 CSV-1 4 < 4 83 < 1 CSV-2 < 3 < 4 87 < 1 (1) - Average of 3 or more Determinations 10

16 TABLE A 1-3: Propane + O 2 Gas Composition (ppmw in Propane) Nominal PPMW O2 Sample O2 CO2 COS H2S 50 Charge Cylinder(1) 51 < 4 < 1 < 1 CSV < 4 < 1 < 1 CSV < 4 < 1 < Charge Cylinder(1) 115 < 4 < 1 < 1 CSV-1 20 < 4 < 1 < 1 CSV < 4 < 1 < Charge Cylinder(1) 1189 < 4 < 1 < 1 CSV < 4 < 1 < 1 CSV < 4 < 1 < Charge Cylinder(1) 2530 < 4 < 1 < 1 CSV < 1 < 1 CSV < 1 < 1 (1) - Average of 3 or more Determinations TABLE A 1-4: Propane + CO 2 Gas Composition (ppmw in Propane) Nominal PPMW CO 2 Sample O 2 CO 2 COS H 2 S 10 Charge Cylinder (1) < < 1 < 1 CSV < 1 < 1 CSV < 1 < Charge Cylinder (1) < < 1 < 1 CSV < 1 < 1 CSV < 1 < Charge Cylinder (1) < < 1 < 1 CSV < 1 < 1 CSV < 1 < 1 (1) - Average of 3 or more Determinations 11

17 TABLE A 1-5: Propane + H 2 S and O 2 Gas Composition (ppmw in Propane) Nominal PPMW H 2 S Sample O 2 CO 2 COS H 2 S - PPMW O 2 5 Charge Cylinder (1,2) 100 < 4 < CSV < 1 < 1 CSV-2 68 < 4 < 1 < 1 5 Charge Cylinder (1,2) 1110 < 4 < CSV < 4 < 1 < 1 CSV < 4 < 1 < 1 10 Charge Cylinder (1,2) 1280 < 4 < CSV < 4 < 1 < 1 CSV < 4 < 1 < 1 (1) - Average of 3 or more Determinations (2) - H 2 S added separately to CSV's as a C6 solution TABLE A 1-6: Propane + H 2 S and CO 2 Gas Composition (ppmw in Propane) Nominal PPMW H 2 S Sample O 2 CO 2 COS H 2 S - PPMW CO 2 5 Charge Cylinder (1,2) < 3 9 < CSV-1 16 < 4 < 1 < 1 CSV-2 9 < 4 < 1 < 1 5 Charge Cylinder (1,2) < < CSV < 1 < 1 CSV-2 < 3 25 < 1 < 1 10 Charge Cylinder (1,2) < 3 13 < CSV-1 < 3 < 4 < 1 < 1 CSV-2 9 < 4 < 1 < 1 (1) - Average of 3 or more Determinations (2) - H 2 S added separately to CSV's as a C6 solution 12

18 TABLE A 1-7: Propane + COS and O 2 Gas Composition (ppmw in Propane) Nominal PPMW COS Sample O 2 CO 2 COS H 2 S - PPMW O 2 10 Charge Cylinder (1,2) 74 < < CSV-1 5 < < 1 CSV-2 25 < < 1 10 Charge Cylinder (1,2) 932 < < CSV < < 1 CSV-2 26 < < Charge Cylinder (1,2) 1250 < 4 96 < CSV-1 3 < 4 86 < 1 CSV-2 12 < 4 95 < 1 (1) - Average of 3 or more Determinations (2) - COS added separately to CSV's as a C6 solution 13

19 XII. APPENDIX A-2. Figures Figure 1. Reproduction of the ASTM Copper Strip Corrosion Standards Plaque 14

20 Figure 2. Instrument Propane Blank 15

21 Figure 3. H 2 S 5 ppmw in Propane 16

22 Figure 4. H 2 S 10 ppmw in Propane 17

23 Figure 5. H 2 S 20 ppmw in Propane 18

24 Figure 6. S 8 5 ppmw in Propane 19

25 Figure 7. S 8 10 ppmw in Propane 20

26 Figure 8. S 8 20 ppmw in Propane 21

27 Figure 9. COS 5 ppmw in Propane 22

28 Figure 10. COS 10 ppmw in Propane 23

29 Figure 11. COS 20 ppmw in Propane 24

30 Figure 12. COS 100 ppmw in Propane 25

31 Figure 13. O 2 50 ppmw in Propane 26

32 Figure 14. O ppmw in Propane 27

33 Figure 15. O ppmw in Propane 28

34 Figure 16. CO 2 10 ppmw in Propane 29

35 Figure 17. CO ppmw in Propane 30

36 Figure 18. CO ppmw in Propane 31

37 Figure 19. H 2 S 5 ppmw + O ppmw in Propane 32

38 Figure 20. H 2 S 5 ppmw + O ppmw in Propane 33

39 Figure 21. H 2 S 10 ppmw + O ppmw in Propane 34

40 Figure 22. H 2 S 5 ppmw + CO 2 10 ppmw in Propane 35

41 Figure 23. H 2 S 5 ppmw + CO ppmw in Propane 36

42 Figure 24. H 2 S 10 ppmw + CO 2 10 ppmw in Propane 37

43 Figure 25. COS 10 ppmw + O ppmw in Propane 38

44 Figure 26. COS 10 ppmw + O ppmw in Propane 39

45 Figure 27. COS 100 ppmw + O ppmw in Propane Note: The top part of the middle strip was exposed to propane vapor due to leakage of some propane 40

46 XII. APPENDIX A-3. Reaction Schemes for Interaction of Trace Contaminants with Copper Scheme 1 Copper Strip Chemistry in the Presence of H 2 S and Sulfur (Simplified) H 2 S + Cu H 2 O II Cu S + H 2 (surface) (black) II 2 Cu S + H 2 S H 2 O I 2 Cu S + 2 H / 8 S 8 (primary corrosion (green/red) product) Cu + 1 / 8 S 8 H 2 O II Cu S (black) Key points Colors will be dependent of corrosion film thickness I Cu S overlain on a copper surface may produce multi-color test II Reaction with S 8 to form Cu S could be the reason for even black discoloration Scheme 2 Copper Strip Chemistry in the Presence of CO 2 and H 2 S Cu + CO 2 H 2 O CuCO 3 + H 2 (surface) (blue-green) CuCO 3 + H 2 O Cu (OH) 2 + CO 2 (blue-green) Cu (OH) 2 + H 2 S Cu S + 2 H 2 O (black) Key points An initial carbonate and hydroxide corrosion film may result in an even black discoloration when H 2 S is present II 41

47 Scheme 3 Copper Strip Chemistry in the Presence of COS H 2 O COS + Cu No immediate chemistry 100ºF H 2 O COS + ½ O 2 CO / 8 S 8 (very slow) COS + H 2 O CO 2 + H 2 S (very slow) Key points None of these reactions take place at a significant rate, although the reaction with O 2 may occur to small degree over the time frame of the test 42