Materials Performance

JUN 2019

Materials Performance is the world's most widely circulated magazine dedicated to corrosion prevention and control. MP provides information about the latest corrosion control technologies and practical applications for every industry and environment.

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42 JUNE 2019 W W W.MATERIALSPERFORMANCE.COM MATERIALS SELECTION & DESIGN C Corrosion is a foremost problem in many industries. In the petrochemical industry it impacts the equipment and assets of refineries and other facilities. Uncontrolled corrosion can cause leaks and component failures, bringing about a reduction in both the perfor- mance and reliability of important equipment. Corrosion can lead to un- expected failures that can be costly in terms of repair costs, environmental damage, and potential harm to hu- mans. Chloride stress corrosion crack- ing (Cl-SCC) behavior of stainless steel (SS) was investigated in a chloride envi- ronment at ambient temperature. This study aims to understand the mecha- nism of increased Cl-SCC susceptibility of machined Type 304L SS (UNS S30403) in a chloride environment. Corrosion is the deterioration process of a material due to reactions with its sur- roundings. There are several ways to try and prevent such damage, with the opti- mum control method relying on an early diagnosis of the corrosion issues that are present. However, such a task is often far from trivial. From the literature, it is noted that materials that have corrosion prob- lems are metals, ceramics, and polymers. Also, many methods are available to moni- tor the corrosion. These methods are used to collect the information on the progress of corrosion damage to a material or on the corrosivity of the environment surrounding the material. A corrosion inspection is usu- Failure Due to Cl-SCC of Austenitic Stainless Steels Muha MM ad h ussain, Integrity Master Pty., Ltd., Sydney, New South Wales, Australia i ntizar h ussain, Integrity Master Pty., Ltd., Islamabad, Pakistan a brar h ussain, University of Science and Technology of China, Hefei, China s hazia Kousar, University of Karachi, Karachi, Pakistan ally a survey of the material to assess the condition at any given moment in time. However, corrosion monitoring consists of a series of sur veys conducted over an extended period. Chlori d e stre ss c orro sion crackin g (Cl-SCC) is a type of SCC and is one of the well-known forms of SCC in the refining and chemical processing industries. This issue can be seen in austenitic stainless steels (SS) and depends on the environ- ment and stress. Hence, this could be one of the reasons that these steels are not con- sidered resistant materials for corrosion damage in the industr y. Damage due to Cl-SCC is easily identifiable by the telltale spider webbed and lightening-array type network of highly branched cracks, which are discussed in this article. In plants, there are many ways for this type of corrosion to occur. This article will discuss that Cl-SCC was obser ved on a plant piping system. This is typically due to inadvertent contamination of equipment with chlorides that were not anticipated by design engineers or who were unaware of the potential consequences of using aus- tenitic SS where chlorides may be present. A study showed how Cl-SCC caused failure and affected the integrity of the plant com- ponent. For this study, a sample of dam- a ge d pi pi n g sy st e m w a s s e l e c t e d f o r examination. Visual Examination Figure 1 shows the external and inter- nal surface of the sample. The external sur- face (left photo) was generally covered with small "slugs" of corrosion products, which were predominantly orientated in the pipe's

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