regulations
New NACE standard introduces DNA-based corrosion detection
Diagnosing MIC Broadly speaking, the primary objectives in characterising a corrosion mechanism
and the extent of biotic of local corrosion products may gases, dissolved oxygen and influence in oilfield and also be affected by constituents scale formation) must also be storage tank systems are: of the bulk fluid composition. evaluated and weighed in 1. Relating corrosion products Typically more than one comparison to potential biotic to the corrosion reactions analytical method is required to contributors to corrosion. 2. Relating microbiological fully characterise the chemical activities to corrosion composition of corrosion Types of microorganisms Since reactions (and corrosion products to address organic microorganisms are ubiquitous products) in a particular and inorganic, crystalline and and extremely versatile, MIC environment amorphous components. usually takes place in the 3. Identifying microbes that support the mechanism in that environment 4. Spatially associating microbes with the corrosion reactions/ corrosion damage at some point in the corrosion process Consideration of these four objectives is essential to accurately diagnose MIC, even for Crude oil export spool piece with a cutout section for MIC examination tank storage of products typically considered to be non-corrosive, as water and Microbiological reactions presence of complex microbial solids accumulation in tank Understanding the composition consortia that are comprised bottoms is nearly inevitable. of the corrosion products, the of more than one physiological next objective is to consider the type of microorganism. Corrosion products extent to which the presence Depending on the Accurately relating corrosion and activities of microorganisms environment, these microbes products to the problem is could have influenced the may include metal-oxidizing inherently more complicated formation of such products bacteria, sulfate-reducing than it sounds. Changes in in the anodic and/or prokaryotes, acid-producing corrosion products can occur cathodic corrosion reactions. bacteria, metal-reducing almost instantly upon removal Microorganisms may influence bacteria and methanogens from a pipeline or storage corrosion reactions in a number that interact in complex tank, and exposure to the of different ways including ways within the structure of atmosphere can significantly promoting concentration biofilms. Characterisation alter test results if precautions and differential aeration cells, of the numbers and types are not undertaken. cathodic depolarisation, of organisms present in the Furthermore, the ability to sulfide production, acidic biofilms associated with collect samples from active species formation and corrosion can be performed in areas of corrosion inside an elevating corrosion current many ways, however, MMM now operating pipeline or storage through biomineralized oxide described in NACE International tank is often quite limited and production. The influence standard TM0212-2012 are may require special access of abiotic environmental providing new insights over tools. A relatively small volume conditions (e.g. chlorides, acid culture-based techniques since
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Source: Torben Lund Skovhus, DTI Oil & Gas, Denmark
Tank farm and storage terminal infrastructures are susceptible to a number of internal corrosion threat mechanisms. Innovative molecular microbiological methods (MMM) are now being employed by the industry to diagnose and reduce the threat of microbiologically influenced corrosion (MIC). Although forensic and medical sciences have used genetic methods for decades to provide valuable diagnostic clues, the application of MMM for solving MIC problems has only recently begun to see broader practical use in the oil, gas and petroleum industry. Over the past several years, an increasing number of technical papers have reported using MMM to investigate corrosion issues in the field. Likewise, the number of service providers and consultants providing these services to the oil and gas industry has also increased. The growing awareness of genetic test methods is further reflected in the recently published NACE International standard TM02122012 ‘Detection, Testing, and Evaluation of Microbiologically Influenced Corrosion on Internal Surfaces of Pipelinesi.’For storage terminal operators, the first step in managing the threat of internal MIC is diagnosing the likelihood of the mechanism becoming a problem in their facility.