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7、n from the publisher. Contact the Publisher, API Publishing Services, 1220 L Street, N.W., Washington, D.C. 20005. Copyright 2007 American Petroleum Institute API FOREWORD Nothing contained in any API publication is to be construed as granting any right, by implication or otherwise, for the manufact
8、ure, sale, or use of any method, apparatus, or product covered by letters patent. Neither should anything contained in the publication be construed as insuring anyone against liability for infringement of letters patent. Suggested revisions are invited and should be submitted to the Director of Regu
9、latory Analysis and Scientific Affairs, API, 1220 L Street, NW, Washington, DC 20005. TABLE OF CONTENTS Executive Summary 1 Methodology 2 Discussion. 3 Carbon Arc Cutting (CAC). 3 Flux Cored Arc Welding (FCAW) . 4 Gas Metal Arc Welding (GMAW or MIG) 5 Grinding 6 Gas Tungsten Arc Welding (GTAW) . 8 O
10、xyfuel Cutting (OFC). 9 Shielded Metal Arc Welding (SMAW or stick welding) 10 Conclusions 12 References 12 List of Figures Figure 1: Overview by Type of Hot Work 1 Figure 2: Overview by Base Metal 2 Figure 3: CAC Results Distribution 4 Figure 4: FCAW Results Distribution 5 Figure 5: GMAW Results Dis
11、tribution. 6 Figure 6: Grinding Results Distribution. 7 Figure 7: GTAW Results Distribution 9 Figure 8: OFC Results Distribution 10 Figure 9: SMAW Results Distribution 11 List of Tables Table 1: CAC Results Summary . 3 Table 2: FCAW Results Summary 4 Table 3: GMAW Results Summary 5 Table 4: Grinding
12、 Results Summary 7 Table 5: GTAW Results Summary . 8 Table 6: OFC Results Summary 9 Table 7: SMAW Results Summary . 11 1 Users of this information should not rely exclusively on the information contained in this document. Sound business, scientific, engineering, and safety judgment should be used in
13、 employing the information contained herein. Hexavalent Chromium Exposures During Hot Work Executive Summary This report details the findings from an air sampling survey contracted by the American Petroleum Institute (API) to evaluate inhalation exposures to hexavalent chromium (chromium (VI) during
14、 seven types of hot work: carbon arc cutting (CAC), flux cored arc welding (FCAW), gas metal arc welding (GMAW or MIG), grinding, gas tungsten arc welding (GTAW or TIG), oxyfuel gas cutting (OFC or torch cutting), and shielded metal arc welding (SMAW or stick). Eighty-three samples were collected in
15、 October and November 2005 at two petroleum sites during maintenance turnarounds by API member companies. An additional 188 samples were collected April June 2006 at three different petroleum company sites by ICU Environmental Health and Safety. Of the 271 total samples, 63 samples were at or above
16、the Occupational Safety and Health Administration (OSHA) action level of 2.5 ug/m3and 51 were at or above the OSHA permissible exposure limit of 5 ug/m3. The following two figures show an overview of the results. The first figure shows the number of samples collected for each type of hot work and th
17、e number of those samples that exceeded the OSHA permissible exposure limit and/or action level. Figure 1: Overview by Type of Hot Work The second figure shows the distribution of samples exceeding the exposure limit and/or action level grouped according to the base metal involved during the sample
18、collection. 6 92739775108521571701741155130130 20406080100120CAC FCAW GMAW (MIG) Grinding GTAW(TIG)OFC(TorchCutting)SMAW(Stick)Total Number of SamplesNumber Action LevelNumber PEL2 API PUBLICATION 4629 Users of this information should not rely exclusively on the information contained in this documen
19、t. Sound business, scientific, engineering, and safety judgment should be used in employing the information contained herein. Figure 2: Overview by Base Metal 665422498026093439012390102030405060708090Carbon Steel Chrome Steel GalvanizedSteelInconel StainlessSteelTotal Number of SamplesNumber PELNum
20、ber Action LevelFrom the two figures, it is apparent that both the type of hot work and the type of base metal must be considered together in order to draw conclusions on expected airborne concentrations. As discussed in the report, sample results were grouped based on type of hot work and base meta
21、l. In some cases, it was also important to look at the environmental conditions and the welding electrode as well. The intent of this survey is to provide sampling data that can be used as objective data to characterize employee exposure to chromium (VI) in accordance with the requirements of 29 CFR
22、 1910.1026. Methodology Samples were collected and analyzed in accordance with the National Institute of Occupational Safety and Health (NIOSH) Method 7605. All activities were sampled by drawing known volumes of air through 37-mm polystyrene cassettes containing PVC filters. Prior to sampling, pers
23、onal air sampling pumps were calibrated to +/- 5% of the recommended flow rate of 1.0 liter/minute with the representative sampler in line. Flow rates were verified after sampling. The air sampling pump was placed on the workers belt and the sampling cassette was placed in the breathing zone outside
24、 the welding helmet. The majority of the samples were TWA samples, collected for the majority of the shift (8- 10- and 12-hour shifts were monitored). Twelve of the samples are considered task samples (sample time was less than five hours). After sampling, the samples and field blanks were kept refr
25、igerated until shipped overnight to the Conoco Phillips Laboratory in Bartlesville, Oklahoma for analysis. The Conoco Phillips laboratory is accredited by the American Industrial Hygiene Association. The samples were analyzed by ion chromatography with UV detection. Results were calculated as a time
26、-weighted average over the total sample time. Adjustment to a specific shift length was not made. HEXAVALENT CHROMIUM EXPOSURES DURING HOT WORK 3 Users of this information should not rely exclusively on the information contained in this document. Sound business, scientific, engineering, and safety j
27、udgment should be used in employing the information contained herein. Samples were collected at five different sites over a period of five months. Samples were collected at three of the sites during maintenance turnaround activities, and during new construction at the remaining two. Discussion The m
28、ain health effects of workplace exposure to chromium (VI) are lung cancer, asthma, bronchitis, and damage to nasal epithelia, skin, and eyes. Chromium (VI) can be produced during welding operations even if the chromium was originally present in another valence state. Welders/cutters were the primary
29、 job tasks sampled, along with some fitters and helpers. During the sampling, notes and observations were recorded concerning the task monitored (welder/cutter, fitter, helper, etc.), the work process (hot work process, base metal, and filler/electrode), the work environment (inside vessel, temporar
30、y fab tent, wide open area, spark enclosure, etc.), the vessel type (if applicable), the ventilation type, respiratory protection, and sample identification information (sample number, date sample collected, worker name, ID, employer). This information, along with the monitoring results, monitoring
31、time, analytical method, and type of sample, was loaded into a Microsoft Access database. The data allows for a variety of combinations for analyzing and interpreting the data. In order to provide information that is both statistically significant as well as being practically relevant, the two main
32、parameters used to compare the data in this report are the type of hot work and base metal. Select data fields have been attached to this report as an Excel spreadsheet. Carbon Arc Cutting (CAC) Only six samples were collected during CAC, and all samples were collected on welders/cutters working ins
33、ide a vessel. Results generally indicate the potential for concentrations to exceed the exposure limit regardless of the base metal. Due to the small sample set, specific conclusions cannot be made about this particular type of hot work. Results are summarized in Table 1: Table 1: CAC Results Summar
34、y Base Metals Total # Samples# PEL Minimum (ug/m3) Maximum(ug/m3) Geometric mean Arithmetic mean All 6 4 1.97 56.599 7.979 14.867 Chrome steel 0 0 0 0 0 0 All Chrome steels 3 2 1.97 9.652 5.581 6.921 Chrome 9% 3 2 1.97 9.652 5.581 6.921 Galvanized steel 0 0 0 0 0 0 Inconel 0 0 0 0 0 0 All Stainless
35、Steels 3 2 2.95 56.599 11.407 22.813 SS 1719% Cr 1 1 56.599 56.599 56.599 56.599 SS 19% Cr 2 1 2.95 8.89 5.121 5.920 4 API PUBLICATION 4629 Users of this information should not rely exclusively on the information contained in this document. Sound business, scientific, engineering, and safety judgmen
36、t should be used in employing the information contained herein. Figure 3: CAC Results Distribution 001131000/= 5000ug/m3Flux Cored Arc Welding (FCAW) Nine samples were collected during FCAW, all when welding on S200-304; 316-321; 330-347; 43 stainless steel (containing 17-19% chromium). The one samp
37、le that exceeded the exposure limit was the only sample that was collected during welding inside a vessel. The remaining eight samples were collected outside the vessel or in open air. The result for this one sample was over 15 times greater than the next highest sample result. Although results indi
38、cate that exposures to chromium (VI) will be below the PEL during FCAW operations on stainless steel outside a confined space, based on the statistical calculations, concentrations in excess of the PEL are still likely to occur. Table 2: FCAW Results Summary Base Metals Total # Samples# PEL Minimum
39、(ug/m3) Maximum(ug/m3) Geometric mean Arithmetic mean All 9 1 0.016 40.869 0.575 5.486 Carbon steel 0 0 0 0 0 0 All Chrome steels 0 0 0 0 0 0 Galvanized steel 0 0 0 0 0 0 Inconel 0 0 0 0 0 0 All Stainless steels 9 1 0.016 40.869 0.575 5.486 SS 1719% Cr 9 1 0.016 40.869 0.575 5.486 HEXAVALENT CHROMIU
40、M EXPOSURES DURING HOT WORK 5 Users of this information should not rely exclusively on the information contained in this document. Sound business, scientific, engineering, and safety judgment should be used in employing the information contained herein. Figure 4: FCAW Results Distribution 4311/= 500
41、0ug/m3Gas Metal Arc Welding (GMAW or MIG) Twenty-seven samples were collected during GMAW (MIG welding) tasks and fifteen of the samples exceeded the exposure limit. All fifteen of these samples were collected when installing a 309 stainless steel welded overlay on a carbon steel vessel using ER309L
42、 electrode. This electrode contains 23% chromium. All were collected at the same job site and mechanical ventilation was in use during each task. Fourteen of the fifteen samples were collected during welding tasks inside a vessel; the exception was collected inside a spark enclosure. Sample results
43、indicate that the PEL is likely to be exceeded during operations on stainless steel inside a vessel. Nine samples were collected during MIG welding on Inconel using Inconel 617 wire. All nine samples were collected during welding inside a vessel, and seven of these welders were using local exhaust v
44、entilation during the sampling. The other two welders used only natural ventilation. Despite the 16% chromium content in Inconel alloy, these results indicate that exposures are not likely to exceed the PEL. Table 3: GMAW Results Summary Base Metals Total # Samples# PEL Minimum (ug/m3) Maximum(ug/m3
45、) Geometric mean Arithmetic mean All 27 15 0.009 51.91 0.907 13.004 Carbon steel 0 0 0 0 0 0 All Chrome steels 0 0 0 0 0 0 Galvanized steel 0 0 0 0 0 0 Inconel 9 0 0.009 0.066 0.013 0.017 All Stainless steels 18 15 0.012 51.91 7.689 19.498 SS 19 Cr 15 15 8.44 51.91 20.599 23.381 Stainless (unspecifi
46、ed) 3 0 0.012 0.15 0.056 0.086 6 API PUBLICATION 4629 Users of this information should not rely exclusively on the information contained in this document. Sound business, scientific, engineering, and safety judgment should be used in employing the information contained herein. Figure 5: GMAW Results
47、 Distribution 00011400120/= 5000ug/m3Grinding A total of 39 samples were collected during grinding operations and five of the samples exceeded the PEL. All five of these samples were collected during grinding inside a vessel while one or more welders were welding in the same vessel and mechanical ve
48、ntilation was in use. The highest sample result (56.626 ug/m3) occurred when there were four welders inside the drum while the sampling took place. Four of the samples were collected during grinding inside a coke drum on SS410 (contains 11-13% chromium) and Inconel rod. The fifth sample was collecte
49、d while grinding inside a vessel above a welder who was gouging. The air was flowing from the bottom to the top of the vessel, across the breathing zone of the individual being sampled. Based on these observations, these sample results were most likely elevated due to the interference from the other operations taking place in the immediate area. Ten other samples collected when grinding on stainless steel were below the PEL. Fourteen samples were collected when grinding on carbon steel and all samples were below the PEL. All seven samples collected when grinding on chrom
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