With the recent increased development of advanced biofuel and bio-based chemical processing plants, materials selections need to be done for many novel plant designs. Organic acids are one of the corrosion-causing byproducts in these plants, along with aqueous carbonic acids, chlorides, etc. (depending on feedstocks). Since no direct past experiences with some unit designs were available, especially for streams with high organic acid contents, it was necessary to extrapolate from literature data and past “somewhat similar” operating experience to select candidate materials and set up future testing programs. The materials under review include austenitic and duplex stainless steels, and nickel-based alloys. This paper summarizes a review done of the risk of organic acid corrosion, and gives examples of the initial materials selection decisions for various types of biofuels units.
Alabbas, Faisal M. (Saudi Aramco) | Kakpovbia, Anthony E. (Saudi Aramco) | Elramady, lyaa (Colorado School of Mines) | Spear, John R. (Colorado School of Mines) | Mishra, Brajendra (Colorado School of Mines) | Olson, David L. (Colorado School of Mines)
It has been accepted that corrosion protection systems and non-destructive inspection methods produce remnant magnetic fields (RMF) to pipeline steel. The present study investigates the influence of remnant magnetic fields inducted by these tools on microbiologically influenced corrosion (MIC) by a sulfate reducing bacteria (SRB) consortium. The corrosion behavior of carbon linepipe steel exposed to different conditions having either a magnetized or nonmagnetized biotic medium, was investigated by electrochemical impedance spectroscopy (EIS), linear polarization resistance (Rp) and open circuit potential (OCP). The corrosion products, biofilm and pit morphology that developed with time were characterized using field emission scanning electron microscopy (FE-SEM). The results confirm substantial increases of bacteria cell attachment, biofilm mass, corrosion and pitting under magnetized biotic conditions compared to a nonmagnetized biotic system. The significant enhancement of MIC under magnetized biotic conditions has been attributed to the synergetic interaction between SRB cells and associated metabolic products with magnetic fields.
Lyublinski, Efim (Northern Technologies International Corporation) | Vaks, Yefim (Northern Technologies International Corporation) | Natale, Terry (Northern Technologies International Corporation) | Posner, Monique (Northern Technologies International Corporation) | Rohland, Wade (Northern Technologies International Corporation) | Woessner, Stephen (Northern Technologies International Corporation) | Singh, Ronnie (Zerust Prevenção De Corrosão Ltda.) | de Souza Siriaco, Heberth (PetróleoBrasileiro S.A.)
Existing corrosion protection methods for mothballed equipment during long term (6 months – 10 years+) storage and shipment in unpredictable environmental and application conditions are not always effective. In addition to their limited protection offered, these approaches tend to be cumbersome, complicated, labor intensive and therefore very expensive. This paper describes a system that allows replacement of the technology by using inhibitors in conjunction with nitrogen or a vacuum to achieve highly efficient corrosion protection of any metal part in different environments (vapor space and liquid). We will discuss new inhibitor formulations and protection principles that are recommended for rapid and sustained corrosion protection of internal metal surfaces of enclosures in industrial environments. These environments can contain acidic gasses and relative humidity up to 100%. The recommended solutions can increase the useful service life of equipment, increase time between failures and reduce time to repair.
A thin layer of semi-conductive material was developed and combined with MMO coated titanium tape anodes for reinforced concrete structures. This system was developed to overcome the problems experienced with existing cathodic protection systems. These problems include poor CP current distribution caused by near-short circuits and shallow concrete cover, acid generation at the anode-concrete interface and dryness of the anode-concrete interface for structures which are not exposed to direct moisture such as tunnels or deck soffit and substructures. In addition, by eliminating complex CP anode engineering and installation, the CP system becomes more users friendly and cost effective for many structure owners and contractors.
This paper discusses the problems with existing CP systems and describes an innovative state-of-the art impressed current CP system. Data obtained from the laboratory and the field trials will be presented.
The environmental fate characteristics of industrial biocides used in oil and gas applications are of increasing concern due to the industry’s drive for sustainable best practices and regulatory pressure on water use and disposal. A detailed understanding of the environmental impact of biocides is critical to their safe use and requires extensive testing. This paper will review current data on the environmental fate and ecotoxicity of commonly used non-oxidizing and oxidizing biocides in oil and gas applications. The associated toxicity to non-target aquatic species and the ecotoxicity profiles for aquatic invertebrates, fish, and algae are presented. Environmental toxicity may be reduced or eliminated following degradation of the biocide active ingredients under environment conditions. Key elements of the environmental fate profile include biodegradability, bioaccumulation, end-product formation, and chemical stability (hydrolysis, photolysis). The specific pathways of biotic and abiotic decomposition and current methods for deactivation of the biocides are reviewed. Collectively, this information provides guidance on the selection and use of oil and gas biocides for various types of applications.
Hansen, Katurah (Det Norske Veritas (USA), Inc.) | Kowalski, Angel R. (Det Norske Veritas (USA), Inc.) | Finneran, Shane (Det Norske Veritas (USA), Inc.) | Land, Jason (Det Norske Veritas (USA), Inc.)
Boundary element analysis (BEA) is an effective and accurate assessment method for modeling large or infinite domains (such as cathodic protection (CP) analysis). The potential and current density were calculated and the distribution trend of the data analyzed. The results of this investigation offer a framework for clarifying ambiguous or misleading data that may results from the uncertainty that can occur when interfering electrical fields using indirect inspection surveys.
Within an oil & gas station, normally different kinds of electrically connected metal structures are cathodically protected as a whole to protect them from corrosion, which is called regional cathodic protection in China. The metal structures protected in a station include buried oil or gas pipelines, sewage pipelines, vent pipelines, tank bottoms, equipment foundations and grounding systems, etc. These metal structures with poor coating or even without coating, such as tank bottom, grounding system, will consume large quantity of protective current and cause problems of interference and shielding, which brings challenges for the design of regional cathodic protection. In this work, several key technologies were studied on regional cathodic protection, such as the determination and reduction of current requirement, the disposal of shielding and interference problems.
The latest revision of NACE TM0177 standard allows notch-machining of Double Cantilever Beam (DCB) specimens for the determination of KISSC using Electro Discharge Machining (EDM-notch) and cutting tools (chevron notch) for the evaluation of Sulfide Stress Cracking (SSC) resistance of Low Alloy Carbon Steels. Chevron specimens are widely used and the obtained value has proved reliability; whereas utilization of EDM notch-specimens is more restricted. One of the reasons may be attributed to the fact that NACETM 0177 does not specify tolerance for the height of the EDM notch(0.3mm or 0.01inch) and only gives a recommendation of arounded or beveled for the slot end in order to avoid side-arm break off.
The intention of this work was to study for which conditions non-pre cracked EDM notch-DCB specimens produced reproducible results and comparable to the ones obtained using chevron specimens; varying the machining parameters and also the configuration of the initial EDM notch in C110 grade. Since pre-cracking loads are considerable low for C110, the use of non-pre cracked EDM-notch specimens appears to be an attractive alternative for reducing testing time. Six EDM conditions were selected for the two configuration of EDM notch DCB specimens (one stated in NACE TM0177 standard and a second one for which the final EDM notch was line-up with the chevron base specimen). All EDM configurations as well as chevron specimens were tested at room temperature in SR39.3 solution saturated with 0.07 bar of H2S and in NACE A solution saturated with 1 bar of H2S. For the ED machining conditions used in this work, it was found that: a)the selection of inadequate ED parameters produced invalid tests due to lack of initiation; b) adequate reproducibility in mild and NACE A when notch height was between 0.26 and0.32mm, c) KISSC obtained with line-up EDM configuration was closer in mean value and dispersion than the ones obtained for the chevron in NACE A solution, d) for some ED machining conditions KISSC in SR39.3 was slightly more conservative than the one obtained with the chevron configuration.
A rupture occurred in a 34-inch (864 mm) crude oil pipeline located in South America that resulted in a discharge of crude oil to the environment. The rupture occurred at the peak of a buckle in a 9-degree construction over bend. It was determined that the buckle was likely due to large pipe displacements induced by soil movement that occurred over time. This report specifically addresses the cause of failure as related to the soil movement and circumstances that led to the rupture of the pipeline. Specifically addressed are the loads necessary to cause the observed buckle of the pipeline and what produced these loads on the pipe. Extensive computational modeling was performed to analyze the soil-to-pipeline interactions during soil movement, possible magnitudes of the loads due to pipe displacement, and the subsequent effects of those loads on the pipe. This report focuses on the range of numerical modeling performed, which included basic beam displacement models to local buckling and damage analyses.
Ultra high strength tubes of UNS N07716 alloy with an actual yield strength higher than 180 ksi (1240 MPa) were produced by a special manufacturing process. These tubes are intended for sour high pressure high temperature (HPHT) environments at temperatures in the range from 200 to 260 °C (400-500 °F), pressures in the range from 200 to 280 MPa (30-40 ksi), for environments containing CO2, H2S, Cl- with or without elemental sulphur. They were characterized in terms of mechanical properties, microstructure, corrosion resistance in sour environments and susceptibility to hydrogen embrittlement. Results of this test programme are herein presented and discussed.