Api publ 7102 1997 scan (american petroleum institute)

American Petroleum Institute Methods for Measuring Naturally Occurring Radioactive Materials (NORM) in Petroleum Production Equipment `,,-`-`,,`,,`,`,,` - Exploration and Production Department API Publication7102 November, 1997 Copyright American Petroleum Institute Provided by IHS under license with API No reproduction or networking permitted without license from IHS Not for Resale S T D * A P I / P E T R O P U B L L U - E N G L 11797 E 0732?40 ObO11bUO B T SI+!- Strategiesfor Today? EnvironnentaZ Partnership One of the most significant long-term trends affecting the future vitality of the petroleum industry is the public's concerns about the &nvironment,health and safety Recognizing this trend, API member companies have developed a positive, forward-looking strategy called STEP Strategies for Today's Environmental Partnership This initiative aims to build understanding and credibility with stakeholders by continually improving our industry's environmental, health and safety performance; documenting performance; and communicating with the public API ENVIRONMENTAL, HEALTH AND SAFETY MISSION AND GUIDING PRINCIPLES c The members of the American Petroleum Institute are dedicated to continuous efforts to improve the compatibility of our operations with the environment while economically,developing energy resources and supplying high quality products and services to consumers We recognize our responsibility to work with the public, the government, and others to develop and to use natural resources in an environmentally sound manner while protecting the health and safety of our employees and the public To meet these responsibilities, API members pledge to manage our businesses according to the following principles using sound science to prioritize risks and to implement cost-effective management practices: To recognize and to respond to cornmuniiy concerns about our raw materials, products and operations To operate our plants and facilities, and to handle our raw materials and products in a manner that protects the environment, and the safety and health of our employees and the public, To make safety, health and environmental consider-ations a priority in our planning, and our develop-ment of new products and processes To advise promptly, appropriate officials, employ-ees, customers and the public ofinformation on significant industry-related safety, health and environmental hazards, and to recommend protective measures To counsel customers, transporters and others in the safe use, transportation and disposal of our raw materials, products and waste mareriab To economically develop and produce natural re-sources and to conserve those resources by using energy efficiently To extend knowledge by conducting or supporting research on the safety, health and environmental effects of our raw materials, products, processes and waste materials To commit to reduce overall emissioq and waste generation To work with others to resolve problems created by handling and disposal of hazardous substances from our operations To participate with government and others in creating responsible laws, regulations and standards to safeguard the community, workplace and environment To promote these principles and practices by sharing experiences and offering assistance to others who produce, handle, use, transport or dispose of similar raw materials, petroleum products and wastes a `,,-`-`,,`,,`,`,,` - Copyright American Petroleum Institute Provided by IHS under license with API No reproduction or networking permitted without license from IHS Not for Resale ~ ~ STD.API/PETRO PUBL 7102-ENGL 1777 0732290 Ob01bûL 731 D Methods for Measuring Naturally Occurring Radioactive Materials (NORM) in Petroleum Production Equipment Exploration and Production Department `,,-`-`,,`,,`,`,,` - API PUBLICATION 7102 PREPARED BY: Rogers & Associates Engineering Corp., December 1989 for the API NORM Issue Group NOVEMBER 1997 American Petroleum Institute Copyright American Petroleum Institute Provided by IHS under license with API No reproduction or networking permitted without license from IHS Not for Resale ~ STD.API/PETRO ~~ PUBL 7102-ENGL 1997 2 ObOLb02 b D FOREWORD API publications may be used by anyone desiring to so Every effort has been made by the Institute to assure the accuracy and reliability of the data contained in them; however, the Institute 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 Suggested revisions are invited and should be submitted to the director of the Manufacturing, Distribution and Marketing Department, American Petroleum Institute, 1220 L Street, N.W., Washington, D.C 20005 `,,-`-`,,`,,`,`,,` - Copyright American Petroleum Institute Provided by IHS under license with API No reproduction or networking permitted without license from IHS Not for Resale ~ STD.API/PETRO PUBL - E N G L 1777 ~ 2 Ob01b03 50Li `,,-`-`,,`,,`,`,,` - TABLE OF COXTESTS Pace S o Chamer ISTRODCCTION 1.1 1.2 1.3 Origin and Xature of XORM Project Objectives and Scope Report Organization 2-1 2.1 2.2 2-1 2-3 Instrument Calibration Variability of Detector Response 2.2.3 Variability Between Detectors Environmental Effects on Detector Variability Electronic Variability of Detectors DEVELOPMENT OF CORRELATIONS 3.1 3.2 3.3 2-3 2-6 2-10 3-1 Theoretical Development of the Detector Correlation 3-1 Laboratory Measurements 3-4 3.2.1 3.2.2 Radioactive Sources Equipment Configurations Tested 3-5 3-7 Results and Analyses 3-9 3.3.1 3.3.2 3.3.3 Determination o f f Determination of Development of the Correlation for Radium Concentration Implementation of the Correlation Correlation for Thin Scales and Gas Plant Equipment Correlations for Soil 3.3.4 3.3.5 3.3.6 1-1 1-3 1-3 SCISTILLATION DETECTOR CHARACTERISTICS 2.2.1 2.2.2 1-1 €t 3-9 3-15 , -a 3-ZU 3-25 ~~ 3-28 3-30 VARIATIOXS IN SOURCE AND DETECTOR GEOMETRY, AND CORRELATION SENSITIVITIES 4-1 4.1 Geometries and Orientations Considered 4-1 4.2 Minimum Detectable Concentrations with a One-Inch Na1 Detector 4-8 The 'L'se of Alternative Detectors 4-13 4.3 Copyright American Petroleum Institute Provided by IHS under license with API No reproduction or networking permitted without license from IHS ii Not for Resale TABLE OF CONTESTS Page S o ChaDter 4.3.1 4.3.2 F E L D APPLICATION OF THE CORRELATIOXS 5.1 5.2 5.3 5.4 5.5 5.6 5.7 Detector Configurations Results Field Measurement Data Field Test of Gas Plant Correlation Tests of Wall Thickness and NORM Thickness Terms Field Test of the Radium Correlation for Large Equipment Field Test of the Radium Correlation for Tubing Field Test of the Radium Correlation for Yard Pipe and Similar Diameter Equipment Field Test of the Radium Correlation for soils SUMMARY AND CONCLUSIONS `,,-`-`,,`,,`,`,,` - Copyright American Petroleum Institute Provided by IHS under license with API No reproduction or networking permitted without license from IHS Not for Resale 4-13 4-13 5- a-1 a-1 5-2 5-6 5-10 5-10 5-10 6- ~ ~ ~ ~ STD-API/PETRO PUBL 7102-ENGL 1997 M 2 ObO1bOS 387 LIST OF TABLES Comparison of Resolutions of the 609 KeV Peak Jleasured with Five Different Detectors 2-8 Gamma Measurements on Three Tubing Samples Using Six Different Scintillation Detectors Under Iden tical Conditions 2-9 Radium-226 Analyses in Selected Bags of Uranium Tailings Used in the Laboratory Correlation Measurements 3-6 3-2 Characteristics of Oil Field Production Tubing 3-10 3-3 Scintillometer Measurements of oil Scale in Small Flat Plate Geometry 3-12 3-4 Scintillometer Measurements of Tailings in Small Flat Plate Geometry 3-13 3-5 Additional Scintillometer Measurements in Small Flat Plate Geometry 3-14 3-6 Scintillometer Measurements of Tailings in Large Flat Plate Geometry 3-18 3-7 Scintillometer Measurements of Tailings in 20 cm Pipe Geometry 3-21 3-8 Scintillometer Measurements of oil Scale in Tubing 3-22 3-9 Summary of Correlation Constant Values 3-23 3-10 Summary of Correlation Results 3-26 3-11 Test Pile Data for Correlation of Gamma Levels with Radium in Contaminated Soil 3-33 3- 12 Gamma Level Data for Correlation of Gamma Levels with Radium Contaminated Soils 3-34 4- Results of Tapered Source Analysis 4-7 4-2 Comparison of Detector Configurations 4-14 2- 2-2 3-1 , 4-3 Comparison of K's of Different Detectors Using cm Tubing Geometry Copyright American Petroleum Institute Provided by IHS under license with API No reproduction or networking permitted without license from IHS iv Not for Resale 4- 16 `,,-`-`,,`,,`,`,,` - Pace S o Tzible S o S T D - A P I I P E T R O PUBL 7102-ENGL 9 m 2 Ob01bOb m LIST OF FIGVRES Pace So Fioure S o Principal Components of the Cranium-238 and Thorium-232 Decay Chains 1-2 2-1 Operating Voltage Plateau for Detector $1 2-2 2-2 Spectra Produced by a 1000 pCi/g Ra-226 Source, Using 1" Na1 Detector #1 2-4 2-3 Spectra Produced by a 1000 pCilg Ra-226 Source, Using 1" Na1 Detector #2 2-4 2-4 Spectra Produced by a 1000 pCYg Ra-226 Source, Using 1" NaI Detector #3 2-5 2-5 Spectra Produced by a 1000 pCi/g Ra-226 Source, Using 1" Na1 Detector #4 2-5 2-6 Spectra Produced by a 1000 pCi/g Ra-226 Source, Using 1" Na1 Detector #5 2-7 2-7 Voltage Plateau Curves for the Five Scintillation Detectors 2-11 2-8 Detector Response vs Varied Thresholds 2-12 3- Major Factors Affecting the Measurement of Radiations from NOFM 3-2 3-2 Counting Configuration for Large Diameter Equipment Simulation 3-8 Counting Configuration for Medium Diameter Equipment Simulation 3-8 Counting Configuration and Sample Points Used to Measure Tubing Detector Response to Well Tubing 3-11 3-3 Comparison of Calculated ft$ for Tailings, Small Plate Geometry 3-16 3-6 Comparison of Calculated f 's with observed fis for o i l Scaie, Small Plate kometry 3-17 3-7 Comparison of Calculated fis with Observed fis for Tailings, Large Plate Geometry 3-19 3-8 B as a Function of Equipment Diameter 3-24 1-1 3-3 `,,-`-`,,`,,`,`,,` - 3-4 Copyright American Petroleum Institute Provided by IHS under license with API No reproduction or networking permitted without license from IHS V Not for Resale ~ S T D - A P I / P E T R O PUBL 7LCIZ-ENGL L797 0732270 ObOLb07 L T LIST OF FIGURES (Continued) Paze S o Fimre So Comparison of Correlation Radium Concentrations u;ith Measured Concentrations in the Laboratory 3-27 3- 10 Variable "A" as a Function of NORM Thickness 3-29 3-11 Variable E as a Function of Equipment Wail Thickness 3-31 3-12 Variable E as a Function of Equipment Wall Thickness 3-33 4- Detector Response for Different Detector Orientations 4-2 4-2 Detector Response as a function of Distance From Surface 4-4 4-3 Gradually Tapered Source 4-5 4-4 Abruptly Tapered Source Configuration 4-6 4-a Bulk Detection Limits for Plate and Tubing Geometries 4-10 4-6 Surface Detection Limits for Plate and Tubing h o m e tries 4-11 Effect of Background Intensity on Bulk Limit of Detection for 1" Na1 Detector 4-12 Comparison of Predicted and Measured NORM Surface Concentrations for Gas Plant Equipment 5-3 Ratio Predicted to Measured NORM Surface Concentrations for Gas Plant Equipment as a Function of Wall Thickrress 5-4 3-9 4-7 5- 5-2 5-3 Ratio Trer,::ted to Measured Radium Concentrations for Thick Equipment Walls 5-4 Ratio of Vorrelation to Measured Radium Concentrations as a Function of NORM Thickness 5-7 Ratio of Correlation to Measured Radium Concentrations for Yew XORM Thickness Correction 5-8 Comparison of Correlation Radium Concentrations with Measured Concentrations for Large Equipment 5-9 5-5 5-6 `,,-`-`,,`,,`,`,,` - Copyright American Petroleum Institute Provided by IHS under license with API No reproduction or networking permitted without license from IHS vi Not for Resale STD.API/PETRO P U B L 7102-ENGL 1997 = ~ 2 ObOLbOô 09b LIST OF FIGC'RES (Continued) Pace S o Figure S o 5- 5-8 5- Comparison of Correlation Radium Concentrations with Measured Concentrations for Tubing 5-11 Comparison of Correlation Radium Concentrations with Measured Concentrations for Intermediate Diameter Equipment 5- 12 Comparison of Correlation Radium Concentrations with Measures Concentrations in Soils and Pits 5-13 `,,-`-`,,`,,`,`,,` - Copyright American Petroleum Institute Provided by IHS under license with API No reproduction or networking permitted without license from IHS v ii Not for Resale S T D - A P I / P E T R O PUBL 7102-ENGL 1777 mI 0732270 D b ü l b B O O b A of fe Measurements were made of the surface activity as a function of time after shutdown of :he equipment The ratio of the surface activity a t long times (greater than four hours) to the short-lived net surface activity one hour after shutdown is fe The short-lived net surface activity is the measured total activity shortly after shutdown minus the long-lived component For example, a deethanizer pump had a net surface count rate of 25,700 cpm one hour after shutdown, and 3,420 cpm nearly six hours after shutdown The fe is obtained from these data by: 3420 fe = = 0.15 (5-1) 25,700-3420 The equipment diameter term has been dropped from the correlation because its effect is too small to be validated, considering the variability between the measured and correlation surface Pb-210 concentrations The agreement between the correlation and measured surface concentrations is shown in Figure 5-1 The average error associated with the correlation is 54 percent Three fourths of the correlation estimates are within a factor of two of the measured value, and all are within a factor of five Since measured surface concentrations generally vary by a factor of two or three in the same general area of a piece of equipment, the correlation agreement is good 5.3 TESTS OF WALL TFíiCKNESS AND NORM THICKNESS TERMS The validity of the wall thickness terms in the correlation is tested with the gas plant data because the NORM thickness term does not interfere Figure 5-2 shows the ratio of the surface contamination predicted by the correlation to the measured value, as a function of the wall thickness The correlation overpredicts for equipment walls greater than two cm However, the radium correlation generally underpredicts for thick walls and thick NOKM layers The ratio of the radium concentrations in oil and gas producing 5-2 Copyright American Petroleum Institute Provided by IHS under license with API No reproduction or networking permitted without license from IHS Not for Resale `,,-`-`,,`,,`,`,,` - Thus, the gas plant correlation for Pb-210 becomes e * / MEASURED S (lo3 dpm/l00 cm2) `,,-`-`,,`,,`,`,,` - RAE-103009 FIGURE 5-1 COMPARISON OF PREDICTED AND MEASURED NORM SURFACE CONCENTRATIONS FOR GAS PLANT EQUIPMENT Copyright American Petroleum Institute Provided by IHS under license with API No reproduction or networking permitted without license from IHS 5- Not for Resale ~~ ~~ ~ ~ ~ S T D - A P I I P E T R O PUBL 7L02-ENGL 1997 m 2 UbûLbA2 I I l T i AVE, SIGMA OF 25 DATA POINTS a O a e O T C I I I O WALL THICKNESS (cm) RAE-103018 FIGURE 5-2 RATIO PREDICTED TO MEASURED NORM SURFACE CONCENTRATIONS FOR GAS PLANT EQUIPMENT AS A FUNCTION OF W A U THICKNESS `,,-`-`,,`,,`,`,,` - Copyright American Petroleum Institute Provided by IHS under license with API No reproduction or networking permitted without license from IHS Not for Resale ~ S T D - A P I / P E T R O P U B L 7102-ENGL 1797 0732270 ObOLbô3 ô 7 AVE, SIGMA OF 13 DATA POINTS e O 2.0 I I l 3.0 5.0 O I 6.0 (cm) t, RAE- 103016 FIGURE 5-3 RATIO OF PREDICTED TO MEASURED RADIUM CONCENTRATIONS FOR THICK EQUIPMENT WALLS Copyright American Petroleum Institute Provided by IHS under license with API No reproduction or networking permitted without license from IHS 5-5 Not for Resale `,,-`-`,,`,,`,`,,` - P = S T D - A P I I P E T R O PUBL - E N G L 1997 0732270 ûbO1bd4 703 m equipment predicted from the correlation and measured is shown in Figure 5-3 as a function of wall thickness and in Figure 5-4 as a function of NORM thickness Since the wall thickness term does not underpredict surface concentrations in gas plants, it is concluded that the source of underprediction of the radium concentrations is mainly due to the NORM thickness term Accordingly, the NORM thickness term was doubled, and its with the gas plant correlation, the equipment diameter term was deleted because it did not improve the accuracy of the correlation The resulting correlation is 0.031 [l + stn/4 + 2&1 - , (5-3) `,,-`-`,,`,,`,`,,` - The ratio of radium concentrations predicted by Equation (5-3) to measured concentrations is shown in Figure 5-5, as a function of NORM thickness Comparison with Figure 5-4 reveals that Equation (5-3)contains a more appropriate NORM thickness term Hence, Equation 15-3) is used for all final field data comparisons 5.4 FIELD TEST OF THE RADIUM CORRELATION FOR LARGE EQUIPMEhT The field data points for radium in equipment were grouped generally according to equipment diameter Thirty-two data points applied to large equipment such as separators and heater-treaters Data for six barrels filled with NORM are also included in this group The NORM density for this group is assumed to be 1.8 g/cm3 except for the barrels Since some of them may be filled with the denser barium sulfate scale, an average density of 2.4 g/m3was used in the correlation The correlation and experimental values are compared in Figure 5-6 The average error associated with the correlation is 50 percent This is well within the uncertainty of the measured values and the sample representativeness for the entire piece of equipment Nearly three-fourths of the time the correlation is within a factor of two of the measured value It is always within a factor of six Copyright American Petroleum Institute Provided by IHS under license with API No reproduction or networking permitted without license from IHS 5-6 Not for Resale ~ STD.API/PETRO PUBL 7102-ENGL 7 R 2 ObO1b85 b4T e e e O O RAE-103014 FIGURE 5-4 RATIO OF CORRELATION TO MEASIJRED RADIUM CONCENTRATIONS AS A FUNCTION OF NORM THICKNESS `,,-`-`,,`,,`,`,,` - Copyright American Petroleum Institute Provided by IHS under license with API No reproduction or networking permitted without license from IHS Not for Resale m STD.API/PETRO P U B L L U Z - E N G L 1797 0732270 ObOLbAb b P n a W O O e I I O a a I 40 30 10 RAE-103015 FIGURE 5-5 RATIO OF CORRELATION TO MEASURED RADIUM CONCENTRATIONS FOR NEW NORM THICKNESS CORRECTION `,,-`-`,,`,,`,`,,` - Copyright American Petroleum Institute Provided by IHS under license with API No reproduction or networking permitted without license from IHS 5-8 Not for Resale ~ STD.API/PETRO PUBL 7102-ENGL 1777 m 2 ObO1bô7 412 MEASURED C (pCi/g) RAE-103010 FIGURE 5-6 COMPARISON OF CORRELATION RADIUM CONCENTRATIONS WITH MEASURED CONCENTRATIONS FOR LARGE EQUIPMENT `,,-`-`,,`,,`,`,,` - Copyright American Petroleum Institute Provided by IHS under license with API No reproduction or networking permitted without license from IHS Not for Resale m ~~~~ ~ ~ ~ STD.API/PETRO PUBL 7102-ENGL 1’7’77 3.5 O732290 übO1b88 359 W FIELD TEST OF THE R4DIzM CORRELATION FOR TUBIXG Figure 5-7 shows the comparison between the correlation predictions and the measured radium concentrations in tubing Once again, nearly three-fourths of the 38 5.6 FTELD TEST OF THE RADIUM CORRELATION FOR YARD PIPE AND SIMILAR DIAMETER EQUIPMENT Figure 5-8 shows the comparison between the predicted radium concentrations and measured radium concentrations for the 26 data points in this group The average error using the correlation is 40 percent The predicted concentration is within a factor of two of the measured value eighty-one percent of the time 5.7 FTELD TEST OF TRE RADIUM CORRELATION FOR SOILS None of the 19 field data points for NORM in soils contains information on the depth of contamination, or whether the NORM is in barium sulfate scales, so the correlation is expected to be less accurate In addition, sampling emors for measuring radium from heterogeneous NORM distributions in surface soils are very large The field test assumes no NORM in barium sulfate and a large NORM depth (&>>8cm) The radium concentration is then predicted by Equation (3-20) C = (3-20) 0.0026 D Figure 5-9 gives the comparison between the predicted radium concentrations in soils and pits, and the measured radium concentrations As expected, the variability is larger than for the previous field data, with the correlation giving an average error of 95 percent For three-fourths of the data points, the correlation gives radium concentrations within a factor of of the measured values Copyright American Petroleum Institute Provided by IHS under license with API No reproduction or networking permitted without license from IHS 5- 10 Not for Resale `,,-`-`,,`,,`,`,,` - predicted radium concentrations are within a factor of two of the measurea r a ~ u m values Ninety-two percent of the data points agree to within a factor of four The average error using the correlation is 53 percent, well within the uncertainties associated with the measurement variability and the radium concentration variability within each section of tubing 100 I I O MEASURED c (103 pciig) RAE-103011 FIGURE 5-7 COMPARISON OF CORRELATION RADIUM CONCENTFLATIONS WITH MEASURED CONCENTRATIONS FOR TUBING `,,-`-`,,`,,`,`,,` - Copyright American Petroleum Institute Provided by IHS under license with API No reproduction or networking permitted without license from IHS 5-11 Not for Resale RAE-103012 FIGURE 5-8 COMPARISON OF CORRELATION RADIUM CONCENTRATIONS WITH MMEASURED CONCENTRATIONS FOR INTERMEDIATE DIAMETER EQUIPMENT Copyright American Petroleum Institute Provided by IHS under license with API No reproduction or networking permitted without license from IHS 5-12 Not for Resale `,,-`-`,,`,,`,`,,` - MEASURED C (103pCi/g) ~~ ~ ~~ ~~~ ~ ~~ ~ ~ `,,-`-`,,`,,`,`,,` - S T D - A P I / P E T R O PUBL 7102-ENGL 1777 W 2 ObOLb71 7Li3 MEASURED Ra (pCi/g) RAE-103013 FIGURE 5-9 COMPARISON OF CORRELATION RADIUM CONCENTRATIONS WITH MEASURED CONCENTRATIONS IN sons A-ND PITS Copyright American Petroleum Institute Provided by IHS under license with API No reproduction or networking permitted without license from IHS 5-13 Not for Resale In summary correlations for radium concentrations and surface containation levels have been developed for XORM scales and sludges in oil production and gas plant equipment and in soils and pits The correlations are based upon laboratory measurements using two types of NOKM, NORM thicknesses up to 10 cm, three geometrical representations of equipment, three equipment wall thicknesses, and seven detector types and configurations They have also been extensively benchmarked using 159 data points from field measurements and sample analyses The correlations for radium concentrations generally agree with the laboratory data to within 20 percent, although occasional data points differ by up to 60 percent Additional errors arising from source and detector irregularities were also examined The field tests provided benchmark information to slightly modify the correlations Specifically the NORM thickness term was doubled, the equipment diameter term was omitted and the gas plant equilibrium fraction was found to be 0.15 The final forms of the correlations are: 0.031 C = - [i + stn / + 2t,] D (6-1) tn Pn S = [l + 2t,l (radium in equipment) D (6-2) (Pb-210 in gas plant equipment) C = 0.0026 D (6-3) (radium in soils and pits) The correlations had an average error of about 50 percent, and predicted the radium and Pb-210 concentrations to within a factor of two about 75 percent of the time This variability is due as much to heterogeneities in the NORM concentrations for an individual piece of equipment as it is to uncertainties in the correlation It is believed Copyright American Petroleum Institute Provided by IHS under license with API No reproduction or networking permitted without license from IHS 6- I Not for Resale `,,-`-`,,`,,`,`,,` - SUMMARY AND CONCLUSIONS STD.API/PETRO PUBL 7102-ENGL L777 S 2 O b O L b 7 b that the correlation gives as accurate an estimate of the acerage radium concentrnticii in a piece of equipment, as a measured radium concentration Ỵrom a single sample The correlation and detector sensitivities were used to deter:Fii.?e m i n i n u n detectable radium concentrations for a variety of conditions Xnimum detecmbie radium concentrations of between and 60 picocuries per gram can be achieved with a bare inch sodium iodide detector Detector collimation, delta measurements, and additional background measurements can yield lower minimum detectable radium concentrations `,,-`-`,,`,,`,`,,` - Copyright American Petroleum Institute Provided by IHS under license with API No reproduction or networking permitted without license from IHS 6-2 Not for Resale S T D - A P I I P E T R O P U B L L - E N G L 1'197 C173227U ObOLLSLi b Information about API Publications, Programs and Services is available on the World Wide Web at: http://www.api.org American Petroleum Institute Copyright American Petroleum Institute Provided by IHS under license with API No reproduction or networking permitted without license from IHS 1220 L Street, Northwest Washington, D.C 20005-4070 202-682-8000 Not for Resale `,,-`-`,,`,,`,`,,` - Additional copies available from API Publications and Distribution: (202) 682-8375 Order No G71021