Understanding the Effects of Hydrogen on SCC of Pipelines

A thesis submitted in Department of Chemical and Materials Engineering University of Alberta, © Zeynab Shirband, 2016.

Near-neutral pH stress corrosion cracks (NNpH SCC) are developed under coating disbondments on the external surface of pipelines where the surface of pipeline is exposed to the soil solution. NNpH SCC initiation and early stage of growth is mainly governed by the dissolution process of steel. …This study aimed at understanding the contribution of these important factors to NNpH SCC. In this study, the role of coating disbondment on hydrogen ingress into pipeline steels and the effects of mill-scale and hydrotesting on NNpH SCC crack initiation are investigated.

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Publicités

Analysis of internal corrosion in subsea oil pipeline

An interesting paper in  » Case study in Engineering Failure Analysis »published on ScienceDirect.com.

Failure of a subsea crude oil API 5L X52 steel pipeline which led to oil leakage has been reported to occur after 27 years in service. Some leaks were found to form at the bottom of the horizontal API 5L X52 steel pipeline near an elbow section which connected the pipeline to a riser.

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Effect analysis of an arc-strike-induced defect on the failure of a post-tensioned threadbar

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An article about a case study published in « Case Studies in Engineering Failure Analysis » – april 2016.

A temporary threadbar used for precast segmental construction broke during the post-tensioning stage before reaching the service load. Failure analysis showed that the premature failure of the bar was due to the presence of an arc strike. The arc strike effects on the material and threadbar integrity are considered.

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Effect of Hydrogen Charging on the Wear Behavior of Spring Steel

spring-steel-wireAn article published in the « International Journal of Engineering Science and Computing« , June 2016.

Spring steel is a prominent piece of material in industrial and automotive application. Hydrogen embrittlement (HE) is an inherent phenomenon, which will occur during the course of service life, at the same time it has to sustain a variety of loads acting on it. Among all the wear of spring steel plays a vital role. Hydrogen embrittlement leads for pre mature failure of the component. In view of this, an attempt was made in this experimental study to performance of hydrogen embrittled spring steel (EN-47 / SAE 6150/SUS 10) under the dry sliding condition. The specimen preparation and the experimentations have been carried out according to the ASTM standards. The experiments performed based on plan of taguchi technique. Cathodic charging is having been adopted for the embrittlement of the spring steel material. A known level of embrittlement has made, wear test has been carried out. Results have shown that, load and sliding distance is more pronounced on the wear of the embrittled spring steel material rather than speed.

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Reduction in diversion due to coil break in CRNO grades of coils

A new « Case study in Engineering Failure Analysis » published on ScienceDirect.com.

This paper reports investigations after diversion due to coil break in cold rolled non oriented (CRNO) grades of coils showed an increasing trend during Jan–May’12 at Silicon Steel Mill (SSM), Rourkela Steel Plant (RSP). Coil break increased from a level of less than 1% during to a level of 30% in May’12. Samples from hot rolled coils and finished coils were taken and detailed metallurgical investigation was carried out to ascertain the genesis of such defects. Further studies were carried out in the processing lines and material flow was tracked from steel making to final product. The probable reasons were identified and corrective measures were taken leading to reduction in diversion due to coil break less than 2%.

Acceder article

Hydrogen embrittlement failure of box-like link-plate

This paper present a failure analysis of box-like link-plate. The failed link-plate is fabricated from 42CrMo steel and the surface of internal hole is demanded to be induction-hardened.

Evidences indicate that the failure of link-plate is due to hydrogen. The possible source for hydrogen was introduced during melting and casting process. A great number of non-metallic inclusions in the link-plate material acted as traps of hydrogen.

Via : http://www.sciencedirect.com/science/article/pii/S1350630713000617