Document ZJXJd6On2M0EJ4K17e6edK8Q8

Interoffice Communication To Mr. John Levardsen, Saddle Brook From o*t R. W. Dillman, Ponca City August 20, 1980 Subjoct VCM Delivery to CertainTeed Since our August 14, 1980 meeting with CertainTeed, X have been reviewing several details of the turbine meter installation at CertainTeed as was requested by Mr. Gellner at that meeting. I have been in touch with Mr. Gil Green who is Product Specialist for Turbine Metering Systems with the Foxboro Company, Foxboro, Massachusetts. In reviewing the installation with him I was made aware of the following factors which may affect this installation. The rate at which VCM is now delivered to CertainTeed from Conoco (approximately 135 to 175 gpn) falls dangerously close to the lower end of the turbine meters linear range which is 100 to 1000 gpm. Mr. Green informed me that if the flow were to any time drop below 100 gpm that the meters stated accuracy could not be assured. He also stated that if the flow rate fell below approximately 70 gpm that the turbine meter would fail to register any flow at all. A two inch turbine meter which has a linear range of 25 to 250 gpm was recommended by Mr. Green as a more suitable choice for the rates given. Another factor which appears significant is the method of temperature compensating the turbine flow measurement to achieve a mass flow signal. The Foxboro equipment in the CertainTeed plant uses a linear relationship between temperature and specific gravity. However, the true relationship between temperature and specific gravity for VCM is decidedly non-linear. Since we feel that VCM is received by CertainTeed from Conoco over a wide temperature range, this appears to be an area where error can be introduced. A temperature compensation device which can better approxi mate this non-linear relationship is recommended. I am enclosing a product bulletin for one such device, the Daniel Industries Model 1863 Temperature Compensating Totalizer. These two factors appear to me as significant enough to warrant further discussion with CertainTeed before entering into an agreement for a second meter installation. We are continuing to study the installation and plan to have data to verify these observations when we see you on August 27. If you have any questions, please let me know. 'Robert W. Dillman Staff Engineer - Instrumentation Central Engineering Department Att: cc w/o att: REL RJA JAD' GJF BAC CUH 00000942? Interoffice Communication To From Date R. J. Andersen J. G. Dopper June 12, 1980 Subject CertainTeed VCM Supply and Quantity Dispute With reference to the report from J. F. Sheara dated April 11, 1980, I would like to add the following summary: BACKGROUND - 5-year VCM supply contract, starting January 1, 1978 for 27-32 MM lbs. annually. Conoco and CT agreed to build a pipeline and share the cost (with a maximum - Conoco had an option to supply an additional volume (40%-60% of CT total requirement of approximately 240 MM lbs. annually). If Conoco would not declare this option before October 1, 1978, Conoco would reimburse $250,000, the CT investments in the pipeline. Conoco did declare its option to supply the add volumes. CT insisted on a discount and our offer expired, since we were only forced to supply at contract conditions. Consequently, we did not reimburse the $250,000. Quantity determination as per contract called for gauging Conoco's shore tanks. HISTORY - Supplies only started in November 1978 due to delays in pipeline in struction. - Prior to start-up we had a dispute on transfer pressure. Conoco agreed to install a low speed/pressure pump only for the purpose of transferring to CT costs fully paid by Conoco. Late 78 and early 79 CT verbally complained that they observed reduced conversion rates in their plant, although they never formally notified us, as is written in the contract. We requested some more data from CT which we only received in August 1979. Several meetings were held but no results were achieved. CT initially had no system to verify the received quantities of VCM. In June they attempted to standardize their filling procedure by using capacitance probes to measure starting inventory level (approx. 10% of tank level) and final inventory level (approx. 80% of tank level). CWH 00000 9430 :> R. J. Andersen June 12, 1980 Page Two The capacitance probes were calibrated with infrared photography. CT claims the above system provided a 10% accuracy. - Although CT is invoiced by the other supplier, PPG,on sphere tank measurements, CT seems to have access on data measured by PPG's idle, not calibrated flowmeter. These data seem to confirm CT's measurements. PPG has two devoted tanks from which they transfer to CT. - Despite CT's conviction on accuracy of above system, they installed a flowmeter in the pipeline during October 1979. As far as we know, this flowmeter has not been calibrated yet (other than in the lab). Although in the beginning the measurements looked encouraging, the 1980 transfers were showing again a 7-8% negative variance for CT. Comparison with the PPG data showed a 1% positive variance for CT. record , according to Conoco and CT data CONOCO CT DIFFERENCE 78 5,200,734 4,834,338 (366,396) 79 39,675,576 36,898,872 (2,776,704) 80 7,500,000 (thru May) _ _ Based on average pricing in 78 and 79 the "discrepancies" amount to $483,000 over this period. CONOCO TRANSFER SYSTEM Conoco is always transferring out of its storage tanks 411 A,B,C. From their tanks we have a pipeline to the docks (for barges and vessels) of approximately four miles. Branched from this we have a line to CT. In the line we have a high speed/pressure pump and a bypass with the special low speed/pressure pump for CT. - Prior to transfer all the relevant valves are closed and the line is "packed". Then the relevant tank is gauged. - CT is warned and the transfer is starting. - Upon notice from CT we shut the valves and gauge again. This is repeated several times. We use correction tables for temperature differences. ewi-f 000009431 R. J. Andersen June 12, 1980 Page Three COMMENTS 1) Although no valve is guaranteed "leak-proof" we cannot explain difference up to 10%. Furthermore, looking to the amount of valves in either direc tion, any leaks would be more at random, rather than one-sided in our favor. 2) Basically, we use the same system for loading vessels. Since 1977 we loaded 42 vessels of which: 24 show an average of a 0.93% higher figure for shore tank measurements versus ship tank measurements 18 show an average 0.89% higher ship's figures than shore Deviations are always at random and only on some incidents as high 3.9% discrepancies were found (2 cases). In overseas shipping we have the benefit of comparing shore L.C., ship after loading, ship before discharging and shore customer. The above shows us an average deviation of 0.9% which is acceptable in industry standards. 3) . Of course, Conoco could consider to load cars at the same time we transfer. Being bad faith, we have not considered this to happen. CERTAINTEED SYSTEM CertainTeed receives product in either one of two ballets, from which they load the reactors. - Initially, conversion rates and capacitance probes were the measuring devices. - Since October they installed a flowmeter. - Each cylinder can take maximum approximately 500,000 lbs. COMMENTS1 1) We checked with two firms specialized in capacitance probes (Robertshaw and Drexelbrook). The consensus was basically: capacitance probes (c.p.) are not accurate, particularly not for inventory control c.p. are not to be used for non-conductive materials (VCM) c.p. are heavily affected by temperature changes and changes in the dielectric constant (moisture) general accuracy is said to be 2-3% under good circumstances CUH 000009432 R. J. Andersen June 12, 1980 Page Four 2) Use of infrared equipment for calibration levels of VCM. In contacting infrared (I.R.) causing equipment manufacturers we found the following conclusions: - I.R. not to be recommended for inventory control because of temperature gradient. Sunlight on the sphere could affect accuracy. Not used often for calibration service. 3) Conversion calculation, particularly over a short time span and small volume (1 MM lbs. maximum) are doubtful. 4) The tanks are in open connection with vapor return system. However, CT claims that the pressure difference would prevent leaks into that system. The only other outlet is the daytank which is closed at the transfer. PPG SYSTEM* 1 2 Basically, the same system as Conoco with a few differences. - Shorter line; can use high speed pump - Dedicated system, closed by blind valves. Based on the above, we concluded that: 1) Conoco's sytem by the fact of not seeing any major discrepancies in loading cars, barges or vessels is basically good. 2) We measure in bigger tanks via a static system which is deemed and accepted to be more accurate. 3. CT1s, prior to the flowmeter devices, were not acceptable as level devices. 4. The short experience with the flowmeter which was not calibrated cannot prove that we have been wrong in the past. (I am convinced that if the meter would show now in 1980 numbers in CTfs favor we would not be reim bursed either over the past 18 months delivery). RECOMMENDATIONS 1) We do not see any justification to reimburse CT over deliveries prior to the flowmeter being calibrated^. 2) For future deliveries we suggest to observe the transfers on both sides to get acquainted with the system. CUH 000009433 R. J. Andersen June 12, 1980 Page Five 3) Flowmeters when calibrated are accepted in the industry as being accurate (used by Dow, Shell). Therefore, 1 suggest to follow the results for some length of time to study any differences. In case, after familiarizing ourselves with their system, we still find differences, I suggest to either 1. Work out an exchange with PPG 2. Install our own meter (cost est. + $60,000) 4) In any case, I feel we should never accept the customers reading as the invoice criteria. After all, we are in the VCM business. Even housewife takes the measurements from the producer or sells of any goods as conclusive evidence. J. G. Dopper /tm cc: JJL, REL, BEAL, JFS, MRS, CSC, JdeB, HLG CUH 000009-434 (conoco) Interoffice Communication To John levardsen - Saddle Brook From J. A. DeBernardi Date August 8, 1980 Subject VCM Transfers - Certain-Teed In July and again in August, our system for providing information to Certain-Teed related to transfers of VCM to them has tended toward the potential of embarrassment of both the Marketing and Product management areas as well as the plant. The delicate nature of our dealings with Certain-Teed indicates the need for all communications with them being well coordinated and understood within our organization prior to being passed on to them. To this end I suggest the following actions be considered. 1) Prior to any conversations with Certain-Teed on transfer volume and/or timing, the production and shipment plan by S&D be reviewed for possible conflicts. 2) The VCM Plant Process Superintendent be contacted to assure that plant problems or circumstances that might influence S&D's plan are included in the production and shipment plan being used for reference. 3) If conflicts arise, alternates be explored prior to contacting Certain-Teed and agreed upon as to their workability by S&D, the plant, and Marketing. The possibility of these conflicts also need to be made known to Certain-Teed up-front and not sneek into the system during the agreed upon transfer period. 4) The exact transfer quantity should be communicated to the plant by S&D or Marketing, not by the customer. 5) Responsibility needs to be assigned to S&D, Marketing, or the plant to make contact with Certain-Teed related to transfer plan, problems, and options, as well as quantity. Different stories to the customer from different people lead to confusion and embarrasement for all. Certainly these suggestions will not eliminate all problems of communication with Certain-Teed. However, the setting of guidelines as suggested above and the adherence to their use by S&D, the plant, and Marketing will improve the present situation and eliminate a great deal of the confusion and potential for embarrassment that presently exists. IS J. A. DeBernardi (conoco) Interoffice Communication To Distribution From M. C. Jernigan and J. D. Morris Date September 30, 1980 Subject VCM Custody Transfer INTRODUCTION The purpose of this study is to determine the cause of transfer quantity discrepancies between our VCM plant and CertainTeed Corporation and offer recommendations for correcting the discrepancies. SUMMARY AND CONCLUSIONS During the month of September, the eleven VCM transfers between the VCM plant and CertainTeed were monitored by Conoco PED engineers stationed in both plants. The discrepancies for the eleven transfers varied individually from -5.2 percent to +9.2 percent with an overall average of +1.7 percent (+ indicates Conoco's measurement is greater). The total quantity transferred, as measured by Conoco for September, was 3,496,999 pounds. See Table I. Several factors were found that probably explain prior discrepancies and, if corrected, can prevent future discrepancies. The most significant of these were procedural errors at CertainTeed which resulted in improper line packing. This appears to have occurred during four of the thirteen transfers in the month of July, causing differences as high as +25 percent. This error was discovered and corrected at the start of the first September transfer and did not effect any of the transfers. See Table II. Other factors causing discrepancies relate to improper temperature correction by Conoco of the liquid VCM densities. One of the most significant is the difference in the actual temperature of VCM received by CertainTeed out of the pipeline versus the temperature used by Conoco to calculate the quantity pumped from the sphere. Individual transfer calculation differences can also be shown to be the result of the inaccuracies of the mechanical devices used to measure sphere outage and temperature. These inaccuracies can cause differences as high as +6.0 percent. Minor revisions to the transfer procedures at both the Conoco and CertainTeed plants and improved adherence to the procedures can reduce the major discrepancies. Modifications to the system will be required in order for Conoco to accurately measure the amount of VCM transferred. The modifications should reduce the inaccuracies and errors to an average monthly discrepancy CUH 000009436 TABLE I SUMMARY SEPTEMBER TRANSFERS--CONOCO/CERTAINTEED1 ansfer No . Date Time Certainteed Meter Reading, Lbs 1 9/11 15 :32 311,500 2 9/12 4:11 317,450 3 9/12 16:27 314,740 4 9/13 5:54 309,600 5 9/13 11:50 313,150 6 9/14 3:35 311,230 7 9/14 7:50 305,960 8 9/15 1:16 315,7 80 9 9/15 5:40 313,850 10 9/15 23:15 320,670 11 9/16 3:50 304,050 Total ' 3,437,980 Conoco Reading. Lbs 320,768 346,733 326,957 312',264 309,168 321,033 290,879 322,831 311,358 327 ,261 307,748 3,496,999 Difference, Lbs(1) +9,268 +29,283 +12,217 +2,664 -3,982 +9,803 -15,081 +7,051 -2,492 +6,591 +3,698 +59,059 % +3.0 +9.2 +3.9 +0.8 -1.3 +3.1 -5.2 +2.2 -0.8 +2.0 +1.2 +1.7 (1) + Denotes Conoco value is higher. MCJ-lkm 9/30/80 CWH 000009437 TABLE It SUMMARY VCM TRANSFERS--CONQCO/CERTAINTEED YEAR TO DATE 1900 Month January February March April May June July August September October November December Year to Date CertainTeed Meter 1,095,920 1,594,150 1,690,130 1,511,200 - 4,269,810 3,133,044 3,437,980 Conoco Measured CD 1,095,234 1,733,814 1,758,137 1,575,964 - - 4,581,599 3,203,812 3,496,999 Difference (2) -686 +139,664 +68,007 +64,7 64 - - +311,789 +70,768 +59,059 % -0.1 +8.8 +4.0 +4.3 +7.3 +2.2 +1.7 16,732,234 17,445,559 +713,325 +4.3 (1) Quantities as reported by the plants (2) + Denotes Conoco number is higher. MCJ-lkm 9/30/80 oooo9 Distribution Page 2 SUMMARY AND CONCLUSIONS (CONTINUED) of +1,0 percent or less. These modifications include a new calculation method and new, improved instrumentation. Using the best available data from the September transfers, the revised calculational method yields an overall discrepancy of +0.9 percent. This is shown in Table III. The turbine meter CertainTeed presently use is a four-inch meter with a range of 100 to 1,000 gpm. During transfers, the flow to CertainTeed averages around 250 gpm. During startup and completion of a transfer, the flow may fall to the lower accuracy range of the turbine meter or possibly even outside its range. During these periods, possible errors may occur in CertainTeed's reported amounts. No numbers are available, though, to quantify the accuracy of their meter. A preliminary design for a turbine meter station for Conoco was prepared and is estimated to cost $200,000. Even though it is believed that a better than +1.0 percent accuracy can be achieved by the meter station, Conoco would still have to monitor by tank gauge periodically to maintain our confidence in its accuracy. The above error factors are summarized in Table IV. DISCUSSION1 1. Line Packing The procedure used to transfer material to CertainTeed is the same procedure used for shiploadings. Essentially the procedure consists of (a) packing the transfer line with the transfer pump, (b) reading and recording the sphere level and temperature, (c) .starting the transfer by opening the valve on the CertainTeed end, (d) stopping the transfer by closing the CertainTeed valve, (e) repacking the transfer line, and (f) reading and recording the sphere level and temperature. At the start of the first September transfer, one procedural error was noted. The CertainTeed operator was opening the CertainTeed valve before line packing was complete. This was immediately corrected by CertainTeed. As a result of this operational error, CertainTeed pressure chart recordings of the transfer line pressure for the months of July and August were reviewed. It was noted that the four excessive July transfer discrepancies occurred when the transfer line was not packed. A Conoco operator packs the transfer line by making the proper valve adjustments for a transfer to CertainTeed and starting the pump with the CertainTeed valve closed. When the pressure in the transfer line reaches the pump deadhead pressure and stabilizes (approximately 150 psig), the line is assumed to be full of liquid VCM. CUH 000009439 TABLE III SEPTEMBER 1930 TRANSFERS OLD-NEW METHOD VERSUS CERTAINTEED 000009 Transfer No. Date AVERAGE TEMP, F Transfer Sphere Line CertainTeed Reading, Lbs 1 9/11 82 97 311,500 2 9/12 83 80 317,450 3 9/12 84 94 314,740 VCM Plant Calcu lation, Lbs Difference from CertainTeed, Lbs % Difference New Calcu lation Method, Lbs Difference from CertainTeed, Lbs 320,768 +9,268 +3.0 309,986 -1,514 346,733 +29,283 +9.3 325,173 +7,723 326,957 +12,217 +3.9 323, 967 +9,227 ' 4 9/13 83 80 309,600 312,264 +2,664 40.8 312,547 +2,947 5 9/13 83 94 313,150 309,168 -3,982 -1.3 304,502 -8,648 6 9/J4 82 80 311,230 321,033 +9,803 +3.1 322,594 +11,364 7 9/14 81 84 305,960 290,879 -15,081 -5.2 292,746 -13,214 8 9/15 82 82 315,780 322,831 +7,051 +2.2 324,803 +9,023 9 9/15 80 80 313,850 311,358 -2,492 -0.8 314,586 +7 36 10 9/15 81 83 320,670 327 ,261 +6,591 +2.0 328,834 +8,164 11 9/16 Total 80 32 304,058 307,748 +3,698 ' +1.2 309,369 +5,311 3,437,980 3,496,999 +59,059 + 1.7 3,469,107 +31,127 (1) + Denotes Conoco value is higher. MCJ-lkm 0/30/80 Z Difference -0.5 +2.4 +2.9 +1.0 -2.8 +3.7 -4.3 +2.9 +0.2 +2.5 + 1.7 +0.9 TABLE IV VCM CUSTODY TRANSFER Error Factors 'RANGE OF INACCURACY(1) % Lbs Recommendations to Correct ACCURACY AFTER CORRECTION % Lbs Line Packing +2.6 +84,000 Install pressure recorder. Adhere to operation pro cedure . - - Density Correction +1.7 +5,100 Incorporate new transfer calculation method and line temperature re corder. Unknown Unknown Varec Gauges +1.0 3,000 Change strapping table. 3.5 1,500 Sphere Temperature 1* a. Old Method of Calculation b. New Method of Calculation 6.5 <0.1 19,500 -- Install thermocouples with digital readout. N/A 1.6 -- 4,800 -- Sphere Temperature Gradients 3.5 10,500 N/A -- 0000 Hn:;i Density Correlation - - Use most accurate density Unknown Unknown correlation. CertainTeed s-.' S3 -* New Metering System (Optional) Unknown - Unknown - Reduce operation error. Maintain flow above 100 gpm. Install turbine meter system. Unknown Unknown 0.5 1 ,500 (1) Based on a 300,000-pound transfer. MC.J-lkm 9/30/80 Distribution Page 3 DISCUSSION (CONTINUED) 1. Line Packing (Continued) If the transfer line is not packed before a transfer, the initial sphere level gauging will be incorrect. Additional material must be used to liquid fill the line; this VCM is, of course, not received by CertainTeed. Figures 1 and? 2 are copies of two July transfer line pressure recordings. Figure 1 is the pressure chart for July transfer No. 8, showing the line was packed correctly both before and after the transfer. The discrepancy for the transfer was less than 0.1 percent. Figure 2 shows very clearly that the transfer line was not packed before the No. 4 transfer was started. The result was a discrepancy of 83,946 pounds, or 24 percent. July transfers Nos. 6, 10, and 12 also have line pressure records which show the transfer line was not packed. These transfers had discrepancies of 24 percent, 19.7 percent, and 26 percent, respectively. The installation of a pressure recorder in the Conoco control room to record the transfer line pressure would aid in assuring proper line packing and in determining process upsets during transfer. The installation of the recorder and improved adherence to the operating procedure by both Conoco and CertainTeed can eliminate the major discrepancies caused by improper line packing. 2. Density Correction The method used by Conoco for calculation of material transferred is an indirect method and is based on a volumetric measurement. The level in Conoco's sphere is recorded before and after each transfer. These values are then converted to gallons of liquid and vapor by the sphere strapping tables. The gallons of vapor and liquid are multiplied by their densities and added together to obtain the total number of pounds in the sphere. The densities are determined by the sphere temperature and the VCM density charts. To obtain the pounds transferred, the mass in the sphere at the end of the transfer is subtracted from the mass at the start. The six-inch CertainTeed line and the section of ten-inch dock line used to transfer VCM to CertainTeed together have a volume of 46,672 gallons. An average VCM transfer of 300,000 pounds at 80F has a volume of 40,010 gallons. The material that CertainTeed would receive from this transfer would be VCM that was displaced from the transfer line and not the material taken from the sphere during that transfer. During the September transfers, the temperature of material received by CertainTeed often exceeded the sphere temperature by 20F. The CUH 000009442 FIGURE 1 TRANSFER LINE PRESSURE RECORDING JULY "TRANSFER NO. 8 JULY 18, 1980 CertainTeed Meter Reading, Lbs 322,340 Conoco Measured, Lbs 322,050 Difference, Lbs 2 90 % 0.09 MCJ - 9/30/80 cun 000009U 3 FIGURE 2 TRANSFER LINE PRESSURE RECORDING JULY "TRANSFER NO. 4 JULY 16, 1980 e CertainTeed Meter Reading, Lbs 347,420 _ $ $ o $ <& e Conoco Measured, Lbs 431,366 Difference, Lbs +83,946 % 24.2 CWH 000009444 MCJ - 9/30/80 Distribution Page 4 DISCUSSION (CONTINUED) 2. Density Correction (Continued) first transfer in September had an average sphere temperature of 82F, while the CertainTeed temperature averaged 97F. The density of VCM at 82F is 1.7 percent greater than the VCM density at 97F. The volume taken from the sphere displaced the same volume in the liquid full transfer line to CertainTeed, but the mass of the volume taken from the sphere was 1.7 percent larger than the mass of the volume CertainTeed received. The discrepancy in a 300,000-pound transfer, as a result of this 1.7 percent error, would have been 5,100 pounds. It is suggested the following method for calculating transfer quantities replace the existing method used by the VCM plant. The sphere outage in gallons would be recorded for each transfer. The density for VCM at the average temperature of the material CertainTeed received would be multiplied by the sphere outage in gallons. The resulting mass would be the correct number of pounds CertainTeed received. This has been done on a trial basis for the September transfers, and the results are shown in Table III. The maximum individual trasnfer discrepancy has been reduced to 4.3 percent from 9.2 percent, while the overall difference is down to 0.9 percent from 1.7 percent. This method would correct the error caused by the temperature difference in the material CertainTeed received versus the temperature of the material pumped into the line from the sphere. A device for averaging and recording the temperature of the VCM in the line at CertainTeed would be required for' this calculation method to be -routine. The recording device would be installed in the Conoco control room, or more economically at CertainTeed. A complete and detailed procedure for this calculation method will be prepared by PED. 3. Varec Gauges CED Standards recommend for remote tank gauging the use of instruments with accuracies of +1F fr temperature and +l/16-inch for level. The standards also recommend the instruments used for these measurements be electronic with digital readout. The Varec gauges used for reading the sphere levels have accuracies of +l/l6-inch; but in conjunction with the strapping tables, the outages determined by level are accurate only to +l/8-inch. A level readout from the middle third of the sphere could be in error +225 gallons. This can effect the accuracy of an average 300,000-pound transfer by up to +1.0 percent or up to +3,000 pounds. CUM 000009445 Discribution Page 5 DISCUSSION (CONTINUED) 3. Varec ?Gaug.es (Continued) The use of the Varec gauges is believed to be adequate for these measurements, although it is recommended the sphere strapping tables be recalculated for 1/16-inch increments. This would increase the accuracy of the outage determihation to +1/16-inch and reduce the effect on transfers to a maximum of +1,500 pounds. 4. Sphere Temperature The bimetallic temperature gauges on the spheres have, at best, a temperature accuracy of +2F. The temperatures recorded from the gauges are used to determine density values in the sphere capacity calculation. The error caused by the +2F inaccuracy has the same effect as using the wrong density values. The inaccuracy can effect a 300,000-pound transfer using the existing calculation method by up co +6.5 percent or +19,500 pounds. Using the new calculation method, the effect would be less than +0.1 percent. 5. Sphere Temperature Gradients During transfers, it has been observed that the VCM in the sphere is often in isothermal layers. This was observed during the September transfers as the temperature of the sphere changed from the initial gauging to the final gauging. This change was as high as 1F to 3F. Since the uniform temperature of the sphere is needed to determine a true mass in the sphere, the use of the initial and final tempratures for transfer calculations will cause inaccuracies. A 1F to 3F change will cause inaccuracies from +2.0 to +3.5 percent or" jKj,000 to +10,500 pounds in a nominal 300,000-pound transfer. In order to achieve a uniform temperature in the sphere, the sphere would have to be recirculated for a long period of time. A reasonable time frame of twelve hours or less for recirculation would be ineffective in achieving a uniform temperature. No recommendations for improving this problem are made at this time, since the revised procedure will not be significantly affected by this problem. 6. Density Correlation The liquid density tables used by the VCM plant are based on a linear equation while the VCM density data in the PED VCM Data Book is nonlinear. The latter data shows higher density values for VCM in the temperature range of 60QF to 100-F than the linear equation does, 0.23 percent higher at 70F, and 0.6 percent higher at 85F. The deviations would affect the calculations of the transfers by the same margins (obviously in Conoco1s favor). The effect on the CertainTeed calculated quantities would be the same, since they have been using the density correlation supplied by Conoco. CUM 000009446 Distribution Page 6 DISCUSSION (CONTINUED) 6. Density Correlation (Continued) Verification of the accuracy of either data source has not yet been made. PED will continue the investigation to determine which data is more accurate. > 7. CertainTeed Meter* * * * * 8 9 The existing method used by CertainTeed for measuring VCM transfers is a four-inch turbine meter system with temperature compensation. The meter has an operating range of 100 to 1,000 gpm. Conoco presently transfer at a pumping rate of 200 to 300 gpm. During initial startup or transfer completion or if a transfer upset occurs, the pumping rate to CertainTeed may fall below 100 gpm. R. W. Dillman's letter of August 20, 1980, to John Levardsen suggests that significant inaccuracies in CertainTeed's meter system will occur if the flow rate falls below the lower operating range of the meter. We do not have any data that quantifies this error. Dillman also addresses the effect of the method of temperature compensation on the turbine flow measurement to achieve a mass flow signal. The use of the linear versus nonlinear VCM density data by CertainTeed would have the same effect on transfer quantities recorded by CertainTeed, as discussed in paragraph 6 above. Recommendations will be made after PED's density study is complete. 8. PPG Shipments CertainTeed receive the bulk of their VCM requirements, 83 percent, from an adjacent PPG plant, while Conoco supply approximately 15 percent of CertainTeed's VCM needs. Although PPG use the same methods for transferring to CertainTeed, their system is not as complex as Conoco*s. PPG's piping is shorter, more direct, and can be completely isolated for transfers to CertainTeed. It is also understood that the majority of the piping is underground, thus preventing some of the thermal problem Conoco encounter. 9. New Metering Station A preliminary design for a custody transfer metering system has been prepared by CED's Instrumentation Section. The metering system will consist of two turbine meters, one a billing meter and the other a check meter. The turbine meter signals will be temperature compensated and totalized to provide a mass flow signal. The mass flow signals will be telecommunicated to the VCM plant control room where a card printer will issue a ticket documenting the transfer. CUH 000009447 Distribution Page 7 DISCUSSION (CONTINUED) 9 New Metering Station (Continued) A preliminary estimate by CED has determined that a capital investment of $200,000 will be required for the installation of the metering system. It would be installed on CertainTeed1s property near the inlet to their storage tanks. -The system will require a periodic maintenance and calibration schedule. As stated in the preliminary design, the system was designed from Conoco*s experience with custody transfer monitoring systems on the Conoco/Monsanto Joint Venture and also based on industry standards set by the American Petroleum Institute and the Instrument Society of America. From literature, it is reported that a turbine meter system can achieve accuracies of jj3.5 percent. Although it is not known what actual field accuracies a meter system in this service will have, it is believed that an accuracy of better than +1.0 percent could be achieved. The metering system will have a built-in self-check capability which will register any discrepancies between the two meters. Even with this capability, it is recommended that periodic checks be made by tank outage to insure meter accuracy. IN PERSPECTIVE The comparison of discrepancies in loading ships to that of transfers to CertainTeed is a very unequal comparison. While CertainTeed transfers range in quantities of 300,000 to 350,000 pounds, shiploadings are in the range from 2,500,000 pounds to 23,000,000 pounds. A +1 percent discrepancy in CertainTeed shipments would range from +3,000 to +3,500 pounds. This same error would be unnoticable in a shiploading. Many of the factors that would affect the CertainTeed transfer accuracy would have an insignificant effect on the accuracy of shiploadings. The major factor which seems to affect the accuracy of both shipment calculations is the inaccuracy of the temperature used in the calculation. Both the inaccuracy of the sphere's bimetallic temperature devices and the problem of VCM being in isothermal layers in the storage tanks were pointed out in L. D. Jensen's 1976 report to R. w. McPherson on VCM ship loading dis crepancies . Cm 000009448 Distribucion Page 8 SUMMARY OF RECOMMENDED ACTION STEPS The following is a list of PED action steps required for the incorporation of the new transfer quantity calculation method and other improvements: 1. Prepare a complete and detailed procedure for the new calculation method. 2. Prepare a design for instrumentation to record the temperature of the VCM in the transfer line directly before the CertainTeed metering system and to calculate a time-weighted average temperature during the transfer. 3. Prepare a design for instrumentation to record pressure in the transfer line. 4. Recalculate sphere strapping tables for 1/16-inch increments. 5. Prepare operational procedure and assist in training operations. Jay Dee Morris Chemical Engineer Chemicals Division Process Engineering Department M. C. Jernigan Senior Process Engineer Chemicals Division Process Engineering Department lkm CC: JJL:REL:JGD:RJA:JGC:RWD J CL:GJF:RWC:JADe:JWW 000009449 CUH