Corrosion Engineering is the specialist discipline of applying science and technology to prevent or control corrosion damage economically and safely. Corrosion engineering often includes design and implementation of materials, structures, devices, systems and procedures to manage corrosion. Corrosion may be defined as the destruction or deterioration of a material due to interaction with its environment.
Metallurgical engineers can apply their knowledge of the chemical, metallurgical, physical and mechanical properties of materials to evaluate material performance under laboratory simulated conditions in aggressive environments.
Mass Loss Corrosion Testing
Mass loss corrosion testing provides a cost-effective means of identifying potential problem areas in new plants and for evaluating alternative materials or protective coating system(s) and/or to quantify existing corrosion problems.
Corrosion coupon preparation and test procedures are performed in accordance with ASTM and NACE standards. Mass loss tests are usually accompanied by semi-quantitative analyses of the corrosion product using a scanning electron microscope with energy dispersive spectrometry which is performed inhouse at SecMet (Pty) Ltd. This facilitates the identification or confirmation of the corrosion mechanism involved, thus providing a powerful corrosion management tool to our clients.
Pre-Stressed Coupon Stress Corrosion Cracking (SCC)
or environments where SCC and/or hydrogen embrittlement (HE) are prevalent, the in-situ testing of pre-stressed SCC coupons in order to select the most suitable material for future replacement of the components or vessel shell is advisable. Typical specimens include C-ring and compact tension (CT) samples. The CT coupons are typically pre-cracked and stressed to predetermined Crack Tip Opening Displacement (CTOD) value. The post-exposure assessment comprised assessment of the CT specimen sides and fractured surface to determination the nature and extent of crack propagation experienced during exposure testing.
Sulphur Reducing Bacteria (SRB) and Microbial Induced Corrosion (MIC) Assessment
Microbially Induced Corrosion (a.k.a. microbial corrosion, bacterial corrosion, bio-corrosion and) is a form of corrosion that is caused or promoted by micro-organisms. MIC is not limited to metals and can also affect non-metallic materials. SRB’s are a common cause of MIC. SRB’s produce hydrogen sulfide, which can cause accelerated corrosion and sulfide stress cracking (SSC). MIC may appear as localised corrosion such as pitting corrosion of vessels or pipelines, particularly in the oil and gas industry. The potential for MIC is assessed based on bacterial growth, fungal growth and the presence and activity of SRB’s.
Salt Spray testing
Salt spray testing is a widespread and long established accelerated corrosion test that produces a corrosive attack to metallic and often coated samples in order to comparatively evaluate the suitability of the material or coating for use in a given environment or as a protective corrosion barrier.
The appearance of corrosion products (rust or other oxides) is evaluated after various intervals. The test duration is variable and is determined by the applicable standard requirement or corrosion resistance of the material or coating. Popular salt spray testing standards include ASTM B117, ISO 9227 and ASTM G85.
Online Corrosion Monitoring
The degradation of equipment due to corrosion and erosion amounts to a significant amount of incurred cost related to scheduled and unscheduled plant shutdowns, repair costs, employee injury and loss of production. A significant portion of this incurred cost can be avoided by online corrosion and erosion monitoring, by reducing operating costs and extending equipment life.
SecMet provides online corrosion monitoring services utilising either Teledyne Cormon corrosion probes and Rohrback Cosasco corrosion probes. The monitoring systems provides holistic engineered packages, asset management and application expertise through corrosion monitoring. The products include Electrical Resistance (ER) and Linear Polarisation (LPR) probes, data transmitters and monitoring software processes data. The software processes real-time corrosion, erosion, pressure, and temperature data from up to 50 monitoring sensors to provide a holistic view of equipment condition. Recorded data can be stored long term and allow sufficient time to identify potential risks to formulate corrective actions, which reduces unscheduled downtime.