Wang, Yefei (Key Laboratory of Unconventional Oil & Gas Development, China University of Petroleum East China, Ministry of Education, P. R. China, School of Petroleum Engineering, China University of Petroleum East China) | Yang, Zhen (Key Laboratory of Unconventional Oil & Gas Development, China University of Petroleum East China, Ministry of Education, P. R. China, School of Petroleum Engineering, China University of Petroleum East China) | Wang, Renzhuo (Key Laboratory of Unconventional Oil & Gas Development, China University of Petroleum East China, Ministry of Education, P. R. China, School of Petroleum Engineering, China University of Petroleum East China) | Chen, Wuhua (Key Laboratory of Unconventional Oil & Gas Development, China University of Petroleum East China, Ministry of Education, P. R. China, School of Petroleum Engineering, China University of Petroleum East China) | Ding, Mingchen (Key Laboratory of Unconventional Oil & Gas Development, China University of Petroleum East China, Ministry of Education, P. R. China, School of Petroleum Engineering, China University of Petroleum East China) | Zhan, Fengtao (College of Science, China University of Petroleum East China) | Hou, Baofeng (School of Petroleum Engineering, Yangtze University)
A novel indolizine derivative inhibitor for acidization was introduced. It could exhibit effective corrosion inhibition at a much lower concentration without propargyl alcohol and shows economic and environmental advantages. From quinoline, benzyl chloride, and chloroacetic acid, two indolizine derivatives were prepared under certain conditions. These inhibitive indolizine derivatives were both synthesised from benzyl quinoline chloride (BQC), which one of the conventional quaternary ammonium corrosion inhibitors used for acidising. The target compound was purified and instrumental analysis methods including elemental analysis, high-resolution mass spectrometry (HRMS), and NMR were used to characterise the chemical structure. The inhibition performance of the indolizine derivatives in 15 wt.% HCl, 20 wt.% HCl, and mud acid (12%HCl + 3%HF) for N80 steel was investigated by weight loss measurement, electrochemical method (potentiodynamic polarization and EIS), and SEM surface morphology assessment.
When 0.1 wt.% indolizine derivative was added, the inhibition efficiency of N80 steel in 15 wt.% HCl at 90 °C increased to 98.8 % and 99.1 % respectively without the synergistic effect of propargyl alcohol: however, in terms of BQC, even at a dosage of 1.0 wt.%, the inhibition efficiency of N80 steel only reached 83.3 % under the same conditions. The novel derivative could impart an improved corrosion resistance effect. Compared with BQC, there are more active adsorption sites in the derivative and therefore the inhibitor could be better fastened to the steel surface. The firmly adsorbed inhibitors would thereby prevent the metal surface from making contact with H+ ions and finally increase the inhibitory effect. As a high-efficiency corrosion inhibitor, the novel indolizine derivatives may offer a new strategy for corrosion protection in acidising.
Microbiologically influenced corrosion (MIC) is considered one of the major causes of oil and gas pipeline failures, costing billions of dollars annually. Despite the increasing research attention attracted to this area, in-situ detection and monitoring of MIC in real time has presented difficulties, due to the complexity of the corrosion processes resulted, directly or indirectly, from the ever evolving metabolic activities of microorganisms. In this work, an amperometric electrochemical biosensor based on a conducting polymer and carbon nanotubes was developed for detection and monitoring of hydrogen sulfide that can be generated by sulfate reducing bacteria, the main culprits of MIC. The single-walled carbon nanotubes (SWCNT s) are functionalized by a conductive polymer - a polythiophene derivative, which enables the formation of carbon nanotube-polymer nanocomposite sensing layer with enhanced signal transduction capability. A cross-linking agent in optimized dosage was used to improve the water stability of the sensing layer without compromising its electric conductivity. Fast detection of sulfide was achieved with good sensitivity, attributed to the large active surface area of carbon nanotubes and excellent conductivity of the nanocomposite sensing layer. The sensor developed paved the way for further development of online sensors for monitoring MIC.
Microbiologically influenced corrosion (MIC), resulting from activities of microorganisms in the biofilms formed on metal surfaces, has been considered a significant factor contributing to failures of infrastructures (~20% failure)1 including oil and gas pipelines. Despite decades of research efforts, the causes of MIC are still not well understood, mainly due to the complicity of the degradation processes involving multiple and/or multi-stage biological, physical, chemical, and electrochemical reactions on metal surfaces. Full dissection and characterization of MIC requires in-depth understanding of MIC mechanisms and utilization of microbiological, surface analytical and electrochemical testing techniques jointly. This entails sophisticated apparatus and time-consuming sampling and analytical procedures off-line. Simple analytical tools for fast and reliable on-line detection and monitoring of MIC are lacking.
Magerstädt, Michael (ROSEN Group) | Raeth, Thorsten (ROSEN Group) | Rentmeister, Nils (ROSEN Group) | Lai, Larry (ROSEN Group) | Forster, Stefan (ROSEN Group) | Altmeppen, Rainer (ROSEN Group) | Sarvi, Ali (ROSEN Group)
Slurry pipes often are exposed to heavy wear at or around the 6 o’clock position. In oil sands hydrotransport and tailings, wear of steel pipes is much higher under erosion-corrosion conditions. Whilst a number of metallic wear protection solutions, e.g., alloys, hardened steels, or chromium- carbide overlays can significantly extend useful life of such pipes, their protective effect can be severely reduced if erosion-corrosion conditions prevail.
Internal coatings made from high-performance polyurethane elastomers often allow similar or somewhat longer life extension compared to such metallic solutions, at a much lower investment cost. Under erosion-corrosion conditions, however, these elastomer coatings last much longer than metallic solutions. Life extension factors of 2-10 have been observed in oil sands slurry lines.
A former disadvantage of polymeric internal coatings was the fact that non-destructive testing and monitoring methods used on steel pipes could not be applied. For almost three years now, “instrumentation spools” in oil sands tailings service have successfully been in operation. The internal coating contains sensors rendering it “intelligent” in that it measures its own wear, including information on actual wear location on the 360 degree circumference. No hole through the pipe wall is required for data transmission to the operator.
This presentation will describe high-performance polyurethane elastomer internal coatings, the intelligent coating system, and field experience with it.
Elastomers Resistant to Wear and to Erosion-Corrosion
In mining, but also in numerous other industries, wear of metal surfaces and particularly the highly detrimental effect of erosion-corrosion, cause high maintenance and repair cost. These effects significantly contribute to limiting useful life of equipment exposed to them. Prominent examples are mining equipment like slurry pipelines, truck beds, slurry pumps, flotation equipment, chutes, and hydrocyclones, Examples from other industries are tracks of chain vehicles (e.g., street repair machines), heavy duty rollers, cutting table surfaces, or snow plough blades.
In the pipeline industry, inline inspection (“ILI”) tools (“pigs”) as well as cleaning pigs bear disks or cups that are exposed to strong erosive wear as well. These disks or cups need to be made from an elastic material since their purpose is to seal the tool against the inner pipe wall to create a pressure differential in the product stream which will propel the pig through the pipeline. Essentially, the disk or cup material needs to combine highest possible elasticity, wear resistance, and tear propagation resistance whilst at the same time having enough mechanical strength to keep its overall shape and not distort in a way that product stream can bypass the tool. Figure 1 shows a selection of ILI tools with cups and disks.
Li, Wei (University of Kentucky) | Landon, James (University of Kentucky) | Irvin, Bradley (University of Kentucky) | Thompson, Jesse (University of Kentucky) | Nikolic, Heather (University of Kentucky) | Liu, Kunlei (University of Kentucky)
Corrosion mitigation is an important topic for amine-based post-combustion carbon dioxide (CO2) capture operations due to the desire to use less expensive but corrosion-vulnerable materials such as low carbon steels in the construction of a capture system. In this study, the corrosion behavior of carbon steel in an in-house solvent was investigated in a pilot-scale post combustion CO2 capture process. Carbon steel specimens were placed inside process units where corrosion problems were previously found in the stripper column and the CO2-rich amine piping. An organic compound was studied as a corrosion inhibitor and degradation inhibitor in a range of 0 to 1000 ppm. It was found that the use of this corrosion inhibitor effectively retarded the corrosion rates of carbon steel in both unit locations.
Anthropogenic carbon dioxide generation from the combustion of fossil fuels such as coal and natural gas is one of the main acid gases projected to contribute heavily to global climate change. 1-2 One effective mitigation option is to adopt post-combustion CO2 capture and sequestration, which is a process consisting of the separation of CO2 from industrial and energy-related sources by typically using aqueous solutions of alkanolamines, and then transporting pressurized CO2 to a storage location for long-term isolation from the atmosphere. It is well known that monoethanolamine (MEA) is a benchmark solvent for the commercial application of post combustion carbon dioxide capture systems because of its cost-effectiveness, high capacity for CO2, fast reaction kinetics, and high removal efficiencies. 3 However, documented results have shown that MEA is highly corrosive to steels in the presence of oxygen, H2S, and CO2. 4-6 This can directly affect the whole system efficiency as well as the economics from solvent losses, unplanned downtime, reduced equipment lifetime, and even injury or death due to the damage by corrosion of main components of equipment made of steel.
Kus, Slawomir (Honeywell Process Solutions) | Srinivasan, Sridhar (Honeywell Process Solutions) | Yap, Kwei Meng (Honeywell Process Solutions) | Li, Hui (Honeywell Process Solutions) | Kozik, Violetta (University of Silesia) | Bak, Andrzej (University of Silesia) | Dybal, Paulina (University of Silesia)
Electrochemical corrosion monitoring techniques such as Linear Polarization Resistance (LPR), Electrochemical Noise (ECN) or Harmonic Analysis are widely recognized for their responsiveness and accuracy for determination of instantaneous corrosion rate. However, field application has generally been limited by the need for a conductive / aqueous process environment. This limitation stems from the fact that electrochemical systems cannot provide reliable readings in media at conductance levels less than 10μS/cm due to significant impact of solution resistance on measured values of total resistance. Recent progress in multi-technique electrochemical systems involving low frequency impedance and harmonic distortion analysis has been shown to overcome this limitation.
Results from studies on corrosion measurement in low conductive, sulfolane-based solutions are presented in this paper. Sulfolane is commonly used in petrochemical processes for extraction of aromatic compounds including benzene, toluene or xylenes. Sulfolane systems, if contaminated by traces of oxygen and at typical process conditions (170-180°C), may lead to sulfolane decomposition and formation of corrosive by-products. Significant corrosion of steel in Sulfolane applications has been reported, primarily in the reboiler-regenerator section. Considering that conductance of sulfolane mixtures varies from 2 to 5 μS/cm, it is obvious that traditional electrochemical monitoring approaches may fail due to extremely high solution resistance.
This paper details results from laboratory corrosion measurements in low conductivity, sulfolane-based fluids utilizing multi-technique electrochemical monitoring. Corrosion measurements conducted on sulfolane showed the importance of proper adjustment of electrode surface area for obtaining of reliable corrosion readings. It has been shown that industrial-type corrosion monitoring has capability for rapid detection of corrosivity in low-conductive, sulfolane-based fluids. Impact of temperature and sulfolane contaminants (oxygen, chlorides) on corrosion of mild carbon steel has also been studied.
Corrosion and its monitoring in Sulfolane Aromatic Extraction
Sulfolane (2,3,4,5-tetrahydrothiophene-1,1-dioxide) is one of the most common solvents utilized in liquid- liquid extraction of benzene/toluene/xylenes (BTX) from naphtha and gasoline fractions. The aromatics extraction by sulfolane is usually achieved at temperatures in the range 180-200°C in a typical extractor- stripper-regenerator configuration as shown on Figure 1. Pure sulfolane under standard operating conditions is considered to be a stable compound and non-aggressive to carbon steel. However, at temperatures about 200°C, process of sulfolane decomposition spikes followed by generation of SO2 and formation of corrosive H2SO3, as shown in the generic Equation 1 below. Further oxidation may lead to formation of H2SO4 with consequent acid corrosion. At temperatures above 230-240°C, the overall decomposition process accelerates significantly with release of high quantities of SO2. Therefore, it is expected that high-temperature areas in aromatics extraction units, such as reboiler and/or regenerator loops, where temperature excursions are highly likely, will be prone to accelerated sulfolane attack.1-4
Starting in 2007 the regulations in the Netherlands state that renewable fuel has to be added to fossil diesel in the context of energy and climate policy. At present, the statutory rate designed to be 7%. Despite the sympathetic image of the use of bio-components, it also has important disadvantages with relation to corrosion for underground steel storage tanks (USTs) which are uncoated and therefore vulnerable for corrosion. This paper describes the results from a current study in which historical data of 1,401 USTs were analyzed for average maximum pit depths over the years 2003 till 2016. Furthermore tank sludge and wall samples from two tanks were analyzed using Next Generation Sequencing to identify microorganisms, to test the hypothesis that MIC has played a role in the formation of the pitting corrosion defects in USTs. The results showed that since the addition of biodiesel the average pit depth increased. The microbial data showed that MIC was likely involved in the formation of the pits and that sampling location is extremely relevant for analysis of MlC. The data also revealed that analysis on the most common MIC suspected microorganisms like sulphate reducing bacteria might not be a sufficient target for USTs.
With the increasing concern about the environment and the understanding that vehicles that use diesel partially produced from vegetable oils or animal vet, called biodiesel, burns cleaner than fossil diesel, biodiesel is considered a good and more sustainable alternative. The use of biodiesel leads to a less harmful exhaust emissions. National regulations are adjusted towards sustainability. Consequently, in the Netherlands, starting in 2007, regulation state that renewable fuel has to be added to fossil fuel in the context of energy and climate policy. Properties of biodiesel are different than properties of pure fossil fuels. One of these differences is that they have the ability to absorb more water. Water can enter the storage tanks mainly from three different sources: infiltration, temperature affected solubility, and condensation.1 Infiltration can occur for example during rainy periods or during fuel loading of the tanks. The temperature is also a source of water accumulation since warmer diesel can hold more water, resulting in the excess of water when the temperature of the diesel drops. Finally, condensation is a source of moisture in fuel tanks, originated from the aeration side connecting to the atmosphere, which results in condensation every time the atmosphere temperature falls down below dew point. The increased amount of water in diesel increases the risks for chemical corrosion as well as the risks for MIC. The difference between chemical corrosion and MIC is that chemical corrosion due to the presence of water is slow and in general homogeneous. MIC is in general fast and local and therefore difficult to predict. Especially in the higher segments since less turbulence is expected due to the location of the filling point which is at the lowest point. Without the effect of turbulence, microorganisms have the ability to adhere to the surface of the tank wall and to grow in time resulting in a firm biofilm. This biofilm is ideal for MIC related microorganisms since it provides an unique and protected environment in which they can live and thrive, leading to severe corrosion defects.
Park, Gyutae (Institute of Technology Innovation) | Seo, Jinseok (Institute of Technology Innovation) | Abbasi, Majid (Institute of Technology Innovation) | Ro, Yunjo (Institute of Technology Innovation)
Corrosion of overhead system in the distillation unit has been a chronic and unresolved issue even with the injection of neutralizer and corrosion inhibitors. Recently, a light naphtha discharge pump (made of UNS J91150 casing and impeller) malfunctioned, which caused severe damage to the impeller. It was subsequently realized that, prior to the malfunction of the impeller, the pH of the water at the second overhead accumulator unexpectedly dropped to 2.6 with simultaneous increase of Fe concentration. Preliminary analysis of the impeller revealed that it had failed from a combination of corrosion and cavitation. To understand the origin of corrosion, extensive water chemistry analysis was performed, which revealed the presence of corrosive species such as sulfate and nitrate ions, presumably from the flue gas, which would have caused pH to drop. Autoclave corrosion tests also revealed that these species would cause significant corrosion of UNS S41000 which is similar to UNS J91150 used in the pump. In-depth electron microscope study (i.e., SEM, EBSD) on corrosion scale and damaged impeller surface was performed to confirm that the damage mechanism was corrosion-induced cavitation. Details of the analysis will be presented and discussed.
Corrosion in the crude unit overhead is a complex phenomenon that impacts refinery reliability and profitability. It is well known in the refining industry that hydrochloric acid (HCl) is the primary corrosive substance to cause overhead system corrosion. Neutralizer, film-forming inhibitors, and wash water systems are some of the typical industry practices to mitigate acidic attack by condensed water containing HCl. The pH and concentration of chloride ion of the water at overhead accumulator is monitored for corrosion control.1-3 Although most of overhead corrosion is well controlled as expected based on properly designed metallurgy and chemical programs, there are still unresolved corrosion issues.
Recently, the pH of the water at the second overhead accumulator of condensate splitting unit unexpectedly dropped to 2.6, with a simultaneous increase of Fe concentration of up to more than 50 ppm. Several days later, a light naphtha (LSR) discharge pump (made of UNS J91150) malfunctioned. Neutralizer injection into the second stage was immediately applied which recovered the pH and Fe concentrations. Early investigations revealed that the pump was out of order from the severe damage of the impeller, which might be corrosion-related. Field monitoring data showed that the chloride ion concentration of water in second stage accumulator was less than 10 ppm, which is still under the maximum limit. Extensive water chemistry analysis and laboratory autoclave corrosion test was performed to determine unknown substances causing the pH drop of the water and to measure the corrosion rate of various alloys in low pH water. In-depth electron microscope study including scanning electron microscope (SEM) and Electron backscattered diffraction (EBSD) of corrosion scale and impeller metal surface was performed as well to investigate the fundamental damage mechanism of pump impeller.
Radiant coils in steam-cracking furnaces operate under severe reducing and oxidizing conditions at temperatures even beyond 1100 °C. Sulphur is present in feedstocks as natural constituent (naphtha cracking) or as deliberate addition (ethane cracking), and can influence the coke formation and also the stability of tube materials.
The influence of sulfur as H2S-addition on the stability or degradation of tube materials and on the coke formation was studied. The investigated samples were alumina-forming- as well as chromia-forming alloys taken from conventional radiant tubes. In a laboratory-scale reactor comparative cracking-decoking tests were applied to the samples. Testing conditions were relevant to industrial steam cracking. Sulfur was continuously added as H2S to the synthetic feed. Sample temperature could be varied during cracking up to 1100 °C.
The influence of continuous H2S addition to the feed on coke formation and on the tube material deterioration was studied. The investigations reflect the impact of sulfur on the rate of coke formation and on the coke morphology. Particular focus is on how sulfur influences the physical and chemical nature of catalytically active sites.
Sulphur stimulates a process of carbon-induced corrosion, which particularly can deteriorate chromia-forming alloys, whereas alumina scales are resistant.
Radiant coils in steam-cracking furnaces operate under severe alternating reducing and oxidizing conditions at temperatures even beyond 1100 °C. The highly reactive atmosphere strongly can affect the coil material, as it can induce corrosion, carburization up to embrittlement, but - most important - coke deposition at the inner tube wall. The increasing thickness of the coke layer during a cracking run reduces the inner free cross-sectional area of the tube and thereby it causes a steadily increasing pressure drop. At the same time the coke layer reduces the heat conductivity of the coil and tubes need to be fired harder in order to keep the gas temperature inside the coil constant.
Hydrazine is used as an oxygen scavenger to control corrosion in steam generating systems, despite being a genotoxic carcinogen. Alternative chemicals, nontoxic corrosion inhibitors or new oxygen scavenger-free water treatment technologies are preferred. A newly developed amine based vapor phase corrosion inhibitor was investigated. Electrochemical tests were conducted and showed a significantly lower corrosion rate in steam generating boilers and boiling water. Short term (720 hours) corrosion tests in boiling water showed a decreased corrosion rate from 5.3 mpy to 1.93 mpy for 50 mg/L VCI and 1.32 mpy (0.001 metal loss per year) for 100 mg/L VCI (Volatile Corrosion Inhibitor) addition. Long term (2,200 hour) corrosion tests in the hot steam generating closed loop system showed a decreased corrosion rate from 8.2-8.9 mpy for the control sample to 0.72-0.74 mpy when washed with 500 mg/L VCI solution. The closed loop system was subsequently maintained at 100 mg/L inhibitor for the test remainder. Inhibitor added at beginning of test resulted in corrosion rate of 1.09-1.24 mpy (with 100 mg/L VCI). XPS (X-Ray Photoelectron Spectroscopy) analysis showed that the amine based inhibitor promoted and stabilized a protective (Fe3O4) magnetite oxide on the pipe internals. This investigation confirmed the inhibitor can be an effective replacement for toxic hydrazine.
The presence of dissolved oxygen in boiler feed water and steam generating systems can present serious problems in a steam generating plant by promoting corrosion and thick scale formation in the feed water system, the boiler and the steam condensate system. Therefore, it is important to remove oxygen from the feed water and also from the condensate where in-leakage can occur. The first step in the elimination of oxygen from the boiler feed water is mechanical deaeration. The second step involves chemical oxygen scavenging to remove the residual oxygen. For many years, sodium sulfite and hydrazine were the preferred chemical oxygen scavengers. However, sodium sulfite contributes solids to the boiler water and hydrazine was found to be extremely toxic.
Oluwabunmi, Kayode (University of North Texas) | Rizvi, Hussain (University of North Texas) | D’Souza, Nandika (University of North Texas) | Nazrazadani, Seifollah (University of North Texas) | Sanders, Steve (University of North Texas) | Hemmati, Vahid (University of North Texas) | Argade, Gaurav (University of North Texas)
The corrosion properties of PBAT/LDH coating on mild steel substrate was investigated. Tafel tests and electrochemical impedance spectroscopy tests (EIS) was used to analyze the corrosion resistance of the coating on the mild steel substrates. The morphological characteristics of the coatings was done using the scanning vibrating electrode technique (SVET) and environmental scanning electron microscopy (ESEM). Buffered saline solution containing NaCl-0.138 M, KCl-0.0027 M at room temperature and pH of 7.4 was used as electrolyte in the 3 corrosion tests. The tafel results showed that least corrosion current density value of 0.315 (μΑ/cm2) was recorded for 50 % LDH concentration in PBAT. This suggests that 50 % LDH in PBAT was about 98.5 % more corrosion efficient than 1018 bare mild steel and 0.7 % more that the 65 % concentration. The EIS results showed a similar trend. The 65 % LDH concentration showed about 25 % greater impedance to current flow over the 50 % LDH concentration in both the nyquist and bode plots. The SVET results revealed that the greatest corrosion protection of the mild steel substrates was observed with 50 % and 65 % LDH coating. This proved that an increased concentration of LDH in PBAT could potentially improve the corrosion resistance of mild steel when in service in a phosphate buffered saline environment.
Metallic materials used in the biomedical field are susceptible to localized corrosion especially pitting when they come in contact with body fluids and other solutions.1 The phenomenon of corrosion, a natural process that all metallic materials irrespective of the service environment suffer from have been examined using different techniques.2,3 Various forms of protective coatings have been used in the past to mitigate this effect.4 The use of organic coatings has recently gained more attention in the medical field as an environmentally friendly and economical technique for the corrosion protection for metals that come in contact regularly with body fluids. Surface coating of many products have to be carried out not only for aesthetic reasons, but specifically to maintain the integrity of the metallic substrate during their service life.5 Poly (butylene adipate-co-terephthalate) (PBAT) an aliphatic-aromatic biodegradable polyester primarily utilized in packaging industry;6,7 was investigated for its potential medical application.8 The non-cytotoxic behavior of the polymer using different cation exchange montmorillonites as filler at less than 10% by weight showed that through cytotoxicity tests, protein absorption analysis and total blood counts, PBAT composites are valuable in biomedical applications.9,10 Though, low hardness values and inherent non-conducting properties makes it suffers rapid delamination when used as a corrosion resistant coating, it was observed that it possessed the ability to enable platelet mobility which improved its mechanical properties with (less than 6%) of layered clay11,12. Based on this, we hypothesized that, reinforcing PBAT with LDH fillers a type of anion exchanged clays also known as hydrotalcite, with a brucite like structure; having a general formula [MII1-xMIIIx(OH)2x]x+(An”)x/n.mH2O, where Mn represents a divalent metal, Mra a trivalent metal, and An- an anion will help to increase the corrosion resistance of PBAT and give birth to a new set of bioinspired coatings suitable for use in medical implants.