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Pipelines exhibit a magnetic anisotropy with the easy axis in the axial direction of the pipe. Three different types of steel API 5L (X52, X56, X60) obtained from out-of-service pipeline sections were investigated with respect to their microstructure, magnetic properties, and magnetostriction. In order to measure the magnetic properties samples were cut parallel as well as perpendicular to the pipe axis. The investigated steels contain 98% iron and 2% of additive elements like Mn, Si, C, and traces of others. The microstructure of steel types X52 exhibited banding along the rolling direction, whereas that of the X56 and X60 steels was negligible. The grain size was between 10 and 25 [micro]m. A similar grain size was observed by raster electron microscopy. The size of the magnetic domains was several micrometers which is distinctly smaller than the observed grain size. The saturation polarization was 2.07 [+ or -] 0.01 T which is 2% below that of pure Fe. Hysteresis loops were measured in a magnetically closed circuit. Saturation in the transversal direction was significantly more difficult to achieve than in the parallel direction. The loops showed clearly the effect of texture induced anisotropy. The stress sensitivity of the loop is caused by the magnetoelastic energy. The ratio of [J.sub.r]/[J.sub.s] was below the theoretical value of 0.75 for a cubic isotropic material indicating also the presence of a texture. These results are in agreement with the texture as observed in the microstructure and with the magnetostriction measurements (longitudinal and transversal) which also showed higher values in the transversal direction. Index Terms--Hysteresis, nondestructive testing, steel.

In this work, the statistical methods for the reliability of repairable systems have been used to produce a methodology capable to estimate the annualized failure rate of a pipeline population from the historical failure data of multiple pipeline systems. The proposed methodology provides point and interval estimators of the parameters of the failure intensity function for two of the most commonly applied stochastic models: the homogeneous Poisson process and the power law process. It also provides statistical tests for assessing the adequacy of the stochastic model assumed for each system and testing whether all systems have the same model parameters. In this way, the failure data of multiple pipeline systems are only merged in order to produce a generic failure intensity function when all systems follow the same stochastic model. This allows statistical and tolerance uncertainties to be addressed adequately. The proposed methodology is outlined and illustrated using real-life failure data of oil and gas pipeline systems. [DOI: 10.1115/1.2894292] Keywords: failure rate, pipeline, repairable system, stochastic process

The molecular interactions of four amino acid compounds are simulated through the density functional (DFT) indexes to study their inhibitive properties. The compounds derived from the amino acids with an aliphatic chain of 10-carbon atoms display inhibitive properties against the corrosion process of carbon steel.