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首页> 美国卫生研究院文献>Journal of Research of the National Institute of Standards and Technology >Analysis of Pipeline Steel Corrosion Data From NBS (NIST) Studies Conducted Between 1922–1940 and Relevance to Pipeline Management
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Analysis of Pipeline Steel Corrosion Data From NBS (NIST) Studies Conducted Between 1922–1940 and Relevance to Pipeline Management

机译：NBS（NIST）研究在1922–1940年间进行的管道钢腐蚀数据分析及其与管道管理的相关性

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Between 1911 and 1984, the National Bureau of Standards (NBS) conducted a large number of corrosion studies that included the measurement of corrosion damage to samples exposed to real-world environments. One of these studies was an investigation conducted between 1922 and 1940 into the corrosion of bare steel and wrought iron pipes buried underground at 47 different sites representing different soil types across the Unites States. At the start of this study, very little was known about the corrosion of ferrous alloys underground. The objectives of this study were to determine (i) if coatings would be required to prevent corrosion, and (ii) if soil properties could be used to predict corrosion and determine when coatings would be required. While this study determined very quickly that coatings would be required for some soils, it found that the results were so divergent that even generalities based on this data must be drawn with care. The investigators concluded that so many diverse factors influence corrosion rates underground that planning of proper tests and interpretation of the results were matters of considerable difficulty and that quantitative interpretations or extrapolations could be done “only in approximate fashion” and attempted only in the “restricted area” of the tests until more complete information is available.Following the passage of the Pipeline Safety Improvement Act in 2002 and at the urging of the pipeline industry, the Office of Pipeline Safety of the U.S. Department of Transportation approached the National Institute of Standards and Technology (NBS became NIST in 1988) and requested that the data from this study be reexamined to determine if the information handling and analysis capabilities of modern computers and software could enable the extraction of more meaningful information from these data. This report is a summary of the resulting investigations.The data from the original NBS studies were analyzed using a variety of commercially available software packages for statistical analysis. The emphasis was on identifying trends in the data that could be later exploited in the development of an empirical model for predicting the range of expected corrosion behavior for any given set of soil chemistry and conditions. A large number of issues were identified with this corrosion dataset, but given the limited knowledge of corrosion and statistical analysis at the time the study was conducted, these shortcomings are not surprising and many of these were recognized by the investigators before the study was concluded. However, it is important to keep in mind that complete soil data is provided for less than half of the sites in this study. In agreement with the initial study, it was concluded that any differences in the corrosion behavior of the alloys could not be resolved due to the scatter in the results from the environmental factors and no significant difference could be determined between alloys. Linear regression and curve fitting of the corrosion damage measurements against the measured soil composition and properties found some weak trends. These trends improved with multiple regression, and empirical equations representing the performance of the samples in the tests were developed with uncertainty estimates. The uncertainties in these empirical models for the corrosion data were large, and extrapolation beyond the parameter space or exposure times of these experiments will create additional uncertainties.It is concluded that equations for the estimation of corrosion damage distributions and rates can be developed from these data, but these models will always have relatively large uncertainties that will limit their utility. These uncertainties result from the scatter in the measurements due to annual, seasonal, and sample position dependent variations at the burial sites. The data indicate that more complete datasets with soil property measurements reflecting the properties of the soil and ground water directly in contact with the sample from statistically designed experiments would greatly reduce this scatter and enable more representative predictions.
机译：在1911年至1984年之间，美国国家标准局（NBS）进行了大量腐蚀研究，其中包括对暴露于现实环境中的样品进行腐蚀破坏的测量。其中一项研究是在1922年至1940年之间对埋在地下的裸钢和锻铁管道的腐蚀进行的调查，这些地点代表了美国不同土壤类型的47个不同地点。在研究开始时，人们对地下铁合金的腐蚀了解甚少。这项研究的目的是确定（i）是否需要使用涂层来防止腐蚀，以及（ii）是否可以使用土壤特性来预测腐蚀并确定何时需要使用涂层。尽管这项研究很快确定某些土壤需要使用涂料，但发现结果差异很大，即使根据这些数据得出的一般结论也必须谨慎。研究人员得出的结论是，影响地下腐蚀速率的因素很多，以至于适当的测试计划和结果的解释是相当困难的事情，定量解释或外推只能“以近似方式”进行，并且只能在“限制区域”内进行。在获得更完整的信息之前。在2002年通过《管道安全改进法》之后，在管道工业的敦促下，美国运输部管道安全办公室与美国国家标准技术研究所取得了联系。 （NBS在1988年成为NIST），并要求重新检查本研究的数据，以确定现代计算机和软件的信息处理和分析功能是否可以从这些数据中提取更有意义的信息。本报告是对这些研究的总结。原始NBS研究的数据使用了多种可商购的软件包进行统计分析。重点是确定数据趋势，以后可在建立经验模型的过程中利用这些趋势，以预测任何给定的土壤化学和条件条件下预期的腐蚀行为范围。这个腐蚀数据集发现了很多问题，但是由于在进行研究时对腐蚀和统计分析的了解有限，这些不足不足为奇，研究者在研究结束之前就认识到了许多缺点。但是，重要的是要记住，在这项研究中，不到一半的场地提供了完整的土壤数据。与最初的研究一致，得出的结论是，由于环境因素导致的结果分散，无法解决合金的腐蚀行为差异，并且无法确定合金之间的显着差异。腐蚀破坏测量值对所测土壤成分和性质的线性回归和曲线拟合发现了一些弱趋势。这些趋势通过多元回归得到改善，并且用不确定性估计建立了代表测试中样品性能的经验方程。这些经验模型对腐蚀数据的不确定性很大，并且超出这些参数空间或暴露时间进行外推将产生额外的不确定性。结论是可以根据这些数据建立腐蚀破坏分布和速率估算方程，但是这些模型将始终具有相对较大的不确定性，这将限制其实用性。这些不确定性是由于埋藏地点每年，季节性和样品位置相关的变化而导致的测量分散。数据表明，更完整的具有土壤性质测量值的数据集可以反映与统计设计的样本直接接触的土壤和地下水的性质，这将大大减少这种分散并实现更具代表性的预测。

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