ABSTRACTCorrosion of metallic pipelines is a significant source of failures and financial burden to drinking water utilities. Cathodic Protection (CP) has been a recognized technology for buried metallic pipelines for decades but has not been widely used in the water industry. Some water utilities have been exploring a variety of techniques to fight external corrosion and to preserve the value of their buried assets however a standardized and defensible approach does not exist. As part of an on-going Water Research Foundation Project (WRF # 4618), technical and economic considerations for CP installation and retrofit of buried water pipelines have been investigated to generate a best CP practice guide-tailored for water utilities application. The effectiveness of a CP program is measured by reduction in breakage rates. Where water utilities do not have specific data on “before and after” CP breakage rates, case studies from other water utilities with similar pipe inventories and operational conditions may be used to make wise CP decisions. This paper discusses the initial results and review of CP techniques that have been successfully applied for existing water pipelines along with multiple case studies obtained from available literature sources or as part of WRF4618 utility surveys and workshops. The challenges that water utilities need to overcome for planning and budgeting CP programs are also briefly discussed. This paper addresses the preliminary findings of the on-going WRF project; a more comprehensive paper summarizing the industry best practices and guidelines will be presented after the project completion.INTRODUCTIONBased on the corrosion IMPACT (International Measures of Prevention, Application, and Economics of Corrosion Technologies) study by NACE released in March 2016, the global cost of corrosion is estimated to be US $2.5 trillion-equivalent to 3.4% of global GDP. A large portion of drinking water infrastructure is reaching its end of useful service life. In the United States, the annual water main breaks mainly due to corrosion was estimated as 240,000 break per year. The cost of replacing over one million miles of corroded water and wastewater pipes was estimated as US $2.1 trillion if all pipes were to be replaced at once. It is reported that 35% to 50% of this cost could have been avoided through proper design, operation, and corrosion prevention . Therefore, implementing and maintaining effective corrosion control programs are essential keys for service life extension of pipe assets.
Zelinka, Samuel L. (USDA Forest Service) | Jakes, Joseph E. (USDA Forest Service) | Kirker, Grant T. (USDA Forest Service) | Vine, David (Argonne National Laboratory) | Vogt, Stefan (Argonne National Laboratory)
ABSTRACTCopper based waterborne wood preservatives are frequently used to extend the service life of wood products when subjected to frequent moisture exposure. While these copper based treatments protect the wood from fungal decay and insect attack, they increase the corrosion of metals embedded or in contact with the treated wood. Previous research has shown the most plausible corrosion mechanism involves the migration of copper ions from the wood treatment through the wood to the metal surface, where they are then reduced. Despite this, under almost all conditions, copper has not been detected in the corrosion products as the proposed mechanism would imply.Recently, synchrotron based X-ray fluorescence microscopy (XFM) was used to examine the wood that had been in direct contact with metal fasteners in a corrosion test. These measurements showed a copper depleted region in the wood directly adjacent to the metal fastener. Based on the size of the region and the copper concentration, the amount of copper in the corrosion products was calculated to be on the order of 500 parts per million. This low concentration explains why previous attempts to find copper in the corrosion products using scanning electron microscopy, energy dispersive X-ray spectroscopy, and powder X-ray diffraction were unsuccessful.Here, we present XFM maps of corrosion products removed from corroded fasteners that had been in contact with preservative treated wood. The XFM maps of the corrosion products clearly show the presence of copper. These measurements definitively confirm the mechanism of corrosion in treated wood and give further insights into where and how the cathodic reaction takes place.INTRODUCTIONIn typical wood construction, metal fasteners are used to join wood to wood or other construction materials. These metal connectors are subject to corrosion from moisture and organic acids within the wood.1-5 In certain cases, wood preservatives or fire retardants are added to the wood and these chemicals affect the corrosiveness of the wood.6
Guo, X. (Norwegian University of Science and Technology (NTNU)) | Gunawardana, P. V. D. S. (Norwegian University of Science and Technology (NTNU)) | Chen, D. (Norwegian University of Science and Technology (NTNU)) | Vanhaecke, E. (Norwegian University of Science and Technology (NTNU)) | Venvik, H. J. (Norwegian University of Science and Technology (NTNU)) | Walmsley, J. C. (SINTEF Materials and Chemistry)
ABSTRACTMetal dusting corrosion is a catastrophic degradation phenomenon that initiates on metallic surfaces of chemical process equipment at elevated temperature and under carburizing atmospheres. It proceeds by a gradual breakdown of the metallic matrix into fine particles. The work is performed to correlate the surface and bulk composition and structure of application relevant alloys to the initial carbon formation and the progress towards metal dusting. UNS N08800 alloy coupons were prepared, polished and oxidized in diluted steam at 540 °C. Formation of carbon on the surface of the pre-oxidized samples was investigated by exposure to reducing, highly carburizing atmosphere (CO in Ar) at 20 bar and varying temperature (550- 750 °C). The resulting surfaces were examined by scanning electron microscopy (SEM), Raman spectroscopy, depth profile analysis by Auger electron spectroscopy (AES) under ion- sputtering. Given that very high carbon activity ac >> 1, the conditions represent an accelerated regime relative to the industrial environment, and hence significant amounts of carbon are formed. The amount and the type of carbon are found to vary strongly with the exposure temperature and the interaction with the metallic matrix. At the highest temperature, also the alloy undergoes considerable change in the elemental distribution as a function of depth.INTRODUCTIONMetal dusting corrosion is a high temperature degradation phenomenon affecting Fe-, Ni- and Co- based alloys when exposed to strongly carburizing gases (carbon activity ac > 1) at elevated temperatures (> 400°C).1-3 The alloy disintegrates into a powdery mixture of metallic, carbidic and carbonaceous dusts. The industrial process conditions cause transfer of carbon to the alloy surface by one of more of the (1) CO reduction, (2) Boudouard, and (3) alkane thermal cracking reactions. For Fe-based alloys,1-2, 4 metal dusting corrosion begins with the formation of Fe3C or Fe5C2 carbides, the volume expansion creates defects on the alloy surface layer.5-6 Carbon atoms diffuses through the carbides and then precipitates as carbon at defects. Accumulation of carbonaceous deposits then separates the carbide particles from the metallic matrix that can be transported away from the surface of the alloy to leave a pit on the surface.
ABSTRACTAt an earlier NACE Symposium, an influential paper was presented characterizing the monolithic isolation joint as a possible weak link in pipeline integrity. We will examine the potential failure points identified in this earlier work and offer strategies, based on experience in the field, to ensure that monolithic isolation joints serve their purpose of eliminating the well-documented cathodic protection challenges historically presented by flanged connections.It is true that the monolithic isolation joint is a sealed system, which obscures the individual components inside. How do you do due diligence on a sealed, discrete system to ensure it will perform over the asset lifecycle?We will put forward a detailed specification including:Contractual requirements that monolithic isolation joints and their components are not just batch tested, but individually tested. We will set out a 5 section regimen consisting of Testing, Material traceability, Material capability, Supplier auditing and Weld certification. Additionally, an easy to use “Supplier Assessment Survey” is included to capture a supplier's rating versus these five critical areas.INTRODUCTIONThe Monolithic Isolation Joint (MIJ) can be the most robust isolation and sealing solution in a pipeline. However, the monolithic isolation joint can also be the weak link in a piping system if the proper steps are not taken in the selection, verification and qualification processes. Due to the fact that the internal components are typically welded within the body of the joint, diligence must be exercised when selecting and specifying the monolithic isolation joint. This paper will endeavor to describe the proper materials; design and testing that should be evaluated prior to specifying the product to insure a long and successful product life.The NACE paper presented at NACE in San Antonio, Texas in March 2014(1) outlined a number of potential pitfalls that can occur with the production and use of a monolithic isolation joint. This paper was a “wake up call” of sorts to some monolithic isolation joint manufacturers. The paper has significantly increased the margin of safety and reliability for some monolithic isolation joints, but the risks still exist for other manufactured isolation joints. To insure receipt of product with increased safety and reliability attributes, this paper will cover: Design, Material Selection, Manufacturing, quality Procedures, Testing.
ABSTRACTThe kinetics of calcium sulfate dihydrate (CaSO4.2H2O, gypsum) scale formation on heated metal surface from aqueous solution has been studied by a highly reproducible technique. It has been observed that gypsum growth takes place directly on heated metal surface without any bulk or spontaneous precipitation in the supersaturated solution. A variety of maleic acid based polymers with different functional groups have been examined for their inhibitory effect on gypsum growth. The results indicate that amount of gypsum scale formed on heated metal surface is strongly affected by polymer dosage and the functional groups present in the polymer. Scanning electron microscopic investigations of the gypsum crystals grown in the presence of anionic polymeric additives show that structures of these crystals are highly modified. Results on the performance of various surfactants and biocides are presented.INTRODUCTIONIn recent years, considerable attention has been given to the various forms of calcium sulfate crystallizing from aqueous solution as affected by temperature, pH, solution stoichiometric ratio of lattice ions, and impurity level.1-3 These and other important factors involved in the nucleation and growth of calcium sulfate dihydrate (CaSO4.2H2O, gypsum), hemihydrate (CaSO4. ½ H2O, plaster of Paris), and anhydrite (CaSO4) should have direct application to the control and inhibition of scale formation. To preclude an excessive rise of operating costs, scale formation has to be prevented. In order to reduce or mitigate scaling, various approaches have been suggested, the most common being the use of small amount (few milligram per liter, mg/L) of scale control additives. The main requirements for an effective additive include: (a) readily available, (b) effective at low dosages, (c) cost effective, (d) non-toxic to environment, (e) stable under oxidizing conditions, (f) resists degradation at high temperatures, and (g) compatible with water treatment formulation components.The effectiveness of a number of inhibitors in preventing or reducing the crystallization of gypsum has been investigated. Amjad4 in a study using the seeded growth method, reported that trace amounts of low molecular weight poly(acrylic acid), PAA, can stabilize supersaturated solutions and lengthen the induction time before the onset of crystallization. The duration of induction times observed in the presence of polymers was found to be greatly influenced by the polymer concentration, solution temperature, pH, and the amount of gypsum seed crystals added. Smith and Huilin5 have examined the effect of number of polyelectrolytes on the growth rate of gypsum. Polymers containing carboxyl groups, such as PAA, and formulated products containing PAA were shown to be particularly effective as gypsum growth inhibitors. Amjad6 in studies on the evaluation of polymers as gypsum scale inhibitors, showed that polymer composition, molecular weight, and ionic charge of the polymer play important roles in imparting the inhibitory activity to the polymer. Among the various homopolymers evaluated, PAA showed the best performance whereas neutral and cationic charged polymers were the least effective inhibitors.
ABSTRACTCorrosion Under Insulation (CUI) is a serious threat that is unavoidable during long term plant operation, and coatings are the most effective measure for preventing CUI. Three types of coatings (i.e., heat resistant epoxy coating, new technology liquid coating (Note), and thermal sprayed aluminum coating) are typical candidates for preventing CUI. However, neither a set of guidelines for selection of the best coating system nor a standardized test method for CUI has been established. In order to establish such a set of guidelines and standardized test method, much more information is needed.This paper evaluates the resistances to CUI of three types of coatings under severe CUI conditions using a vertical pipe test method1. Certain possible improvements in the test method are also discussed.Note: “Inorganic copolymer or coatings with an inert multipolymeric matrix” specified as coating systems CS-6 and SS-5 in NACE(1) SP01982INTRODUCTIONCorrosion Under Insulation (CUI) is a serious threat that is unavoidable during long term plant operation. The severity of CUI varies depending on various factors, such as continuous or cyclic operation, materials selection, selection of coatings and thermal insulation systems, and so on. Among these factors, selection of the coatings systems is the most important factor for preventing CUI because the coating is the final barrier for protecting substrates from corrosion.Coatings are selected based on exposure conditions. Recommended coating systems for CUI have been proposed in some international standards, and the following coating systems are typical candidates:Heat resistant epoxy (e.g., phenolic and novolac epoxies)Inorganic copolymer or coatings with an inert multipolymeric matrix (ICM)Thermal sprayed aluminum (TSA)However, neither a set of guidelines for selection of the best coating system nor a standardized test method for CUI has been established. It should be noted that J. McDonald, et al. pointed out that different coatings showed different behaviors under different test protocols3. The complexity of the mechanism of CUI causes difficulties in establishing such guidelines and a standardized test method. In order to achieve that goal, much more information about coating performances under CUI conditions is needed, including not only experimental data but also data from operating plants.
Bartling, Craig (Battelle Memorial Institute) | Kucharzyk, Kate H. (Battelle Memorial Institute) | Mullins, Larry (Battelle Memorial Institute) | Minard-Smith, Angela (Battelle Memorial Institute) | Busch-Harris, Jennifer (ConocoPhillips)
ABSTRACTMicrobiologically influenced corrosion (MIC) is a significant source of pitting corrosion affecting oil and gas pipelines, wells, and a variety of surface facilities. Understanding of MIC is greatly enhanced through DNA and protein sequencing technologies. This paper highlights the need to understand the methods used to generate the data, the data quality, and the limitations associated with data interpretation through a case study involving the metagenomics and proteomic analysis of pig envelope debris and seawater samples from various locations within a seawater injection system suspected to be suffering from MIC. In this study, sequencing was performed both with and without 16S rDNA gene amplification. Following bioinformatics testing, the resulting data showed dramatically different results when comparing the 16S sequence data to the shotgun-based sequence data. We also showed that the difference between using a RefSeq (NCBI) downloaded in 2013 versus an updated database (2015) significantly impacted data interpretations. One particular organism, Sedimenticola selenatireducens, was found to dominate the relative abundance of the samples when the updated database was used, while it was not identified when the 2013 database was used. Further, proteomic information was used to confirm the presence and abundance of particular organisms and expressed genes.INTRODUCTIONMicrobiologically influenced corrosion (MIC) is a significant source of pitting corrosion affecting oil and gas pipelines, wells, and a variety of surface facilities. Understanding of MIC is greatly enhanced through DNA and protein sequencing technologies. Both shotgun and targeted investigations can provide useful information regarding the presence and type of MIC occurring. However, the methods used to generate the data, the data quality and the limitations associated with data interpretation should not be underestimated. From sample receipt through data interpretation, each step of the process can impact the final results. While one set of protocols is not necessarily universally used, standard operating procedures (SOPs) should be developed to ensure that samples are analyzed in a consistent manner with the appropriate quality controls. Sample extraction and preparation for sequencing is a key step in any environmental sample examination, particularly for metagenomics and proteomics. For metagenomic processing, purified DNA can be sequenced (via direct sequencing or indirect hybridization methods) with or without prior target gene amplification. Shotgun-based metagenomic approaches provide robust estimates of microbial community composition and diversity without the need to target and amplify a specific gene, but more sequence data are needed. Furthermore, phylogenetic classification of microorganisms using shotgun sequencing is seldom coupled to 16S-based classification, and a few recent studies have identified discrepancies between the different classification methods, usually with regard to the level of resolution obtained. For shotgun- based metagenomic analyses that seek to identify organisms and genes based on sequence alignment to publically-available databases, the source and comprehensiveness of the database is critical. Here we use a case study to illuminate several factors that should be considered if omic-based examinations are used for MIC-impacted sites.
ABSTRACTThe measurement and interpretation of cathodic protection (CP) data in plant (i.e., complex) facilities present inherent challenges where mixed metals are electrically continuous with the protected structure. Often there is no attempt to electrically isolate the on-plot buried steel piping networks from the facility for safety and practical considerations. Coupons can be used to assist in the evaluation of CP levels on buried steel piping in mixed-metal circuits. However, the present industry practice of disconnecting the coupon from the mixed-metal circuit to measure the potential and polarization, as described in NACE SP0104-2014 and BS EN 14505:2005, raises concern if the instant-disconnect condition is a true representation of the CP conditions. Another common practice of not interrupting the CP current while measuring coupon-to-soil potentials is also a concern where closely coupled impressed current anode systems are installed adjacent to the buried piping systems. Alternate criteria are often necessary in situations where the polarized -850 millivolt (mV) CSE potential criterion is impractical because of the impact of the buried copper grounding system and other bare metallic structures. Coupons can be used to take advantage of the alternate criteria listed in NACE SP0169-2013 and BS EN 14505:2005. Although coupons provide valuable information in mixed-metal circuits, the data obtained can increase confusion and raise additional questions on the protection status. This paper attempts to address some of the issues and offers a method on how coupons can be used to evaluate the 100 mV polarization criterion in mixed-metal circuits.INTRODUCTIONAlthough coupons have long been recognized as a valuable tool for evaluating cathodic protection (CP) conditions on buried piping systems, their use in plant (i.e., complex) facilities can increase confusion and raise additional questions on the protection status. Plant facilities frequently include extensive buried networks of bare conductors (including copper), steel-in-concrete, mixed-metal circuits, different fill materials and buried protected structures that are within the influence of closely coupled impressed current anodes. These and other factors present inherent challenges with regard to CP measurements and the interpretation of data.Electrical isolation can be impractical to establish and maintain on networks of steel piping systems within plants, depending on the complexity and nature of the facility and equipment. Often there is no attempt to electrically isolate on-plot networks of buried steel piping from the plant, as is common practice for cross-country pipelines and offsite piping. Safety and practical considerations are the key reasons for this philosophy, including avoidance of electrical isolation devices in classified areas and the potential for arcing, reducing touch voltage hazards, and minimizing the propensity for CP downtime as the failure of a single isolation device in a system can result in complete loss of protection. There is also a more than incidental chance of contact between the protected piping and steel reinforcement, etc. In critical double containment piping systems, where fabrication requires 100% welded construction, mechanical fittings may not be permitted. In these situations, the CP system is designed to account for the mixed-metal circuit, often using impressed current closely coupled anodes that are distributed throughout the piping network. When coupons are used in this type of system, the coupon is also within the zone of influence of the current-discharging anode.
ABSTRACTDuplex stainless steels have been actively developed by European companies since 1935. Their properties make them very attractive compared to equivalent austenitic grades. They indeed exhibit higher resistance to stress corrosion cracking, higher mechanical properties and lower alloy cost. They are today widely used in many industrial sectors for instance in the oil & gas, chemical, pulp & paper and water industries. Duplex stainless steels are also relevant candidate materials for architecture, building and construction projects especially when considering sustainability and Life Cycle Cost.This paper provides an overview of the main properties of duplex stainless steels in terms of chemical composition, mechanical and physical properties. Then, the results of an extensive atmospheric field test program are reported, confirming that duplex stainless steels can be interesting candidate materials for architecture, building and construction projects compared to the ferritic-martensitic grade UNS S41003 and standard austenitic grades S30403 and S31603. Finally, the results of a life cycle cost study for the construction of a storage tank will be given.INTRODUCTIONDuplex stainless steels have been actively developed by European companies since 1935. Their properties make them very attractive compared to equivalent austenitic grades: higher resistance to stress corrosion cracking, higher mechanical properties and lower alloy cost. They present excellent cost/properties ratios particularly in critical applications including: oil and gas industry, chemical industry, pulp and paper industry, water systems, desalination plants, pollution control equipments, and chemical tankers.The use of duplex stainless steels in civil engineering for architecture, building and construction projects requiring good corrosion resistance is partly justified by the reduction of maintenance costs. An appropriate material selection will indeed prevent corrosion problems generated by the atmosphere and thus, frequent painting required for steel structures will not be needed anymore.In addition, the duplex stainless steels grades (UNS S32202, S32304, S31803, S32750) have a strong development potential for these applications thanks to additional benefits:
Michel, James H. (Copper Development Association Inc) | Richardson, Ivan (Copper Alloys Ltd) | Powell, Carol (Copper Development Association Inc) | Phull, Bopinder (Copper Development Association Inc)
ABSTRACTSince antiquity both wrought and cast forms of copper alloys have exhibited significant corrosion resistance in marine environments. Their properties have been developed and modified over the years to meet today's exacting engineering challenges and continue to offer solutions to a range of industries requiring reliability in seawater including commercial and naval shipbuilding, offshore seawater- handling and firewater systems, and thermal desalination plants. This paper describes the range of copper alloys in marine service today and the evolution of applications which include ships' cannon and hull sheathing in 18th and 19th century and condenser and seawater piping requirements which spurred concentrated investigations in the 20th century. The latter led to the development and introduction of copper-nickels and nickel aluminum bronzes (NABs), which are now the most widely used marine engineering copper alloys. The direction of future developments is also discussed.Technically, the paper covers the influence of refined composition and/or heat treatment which have optimized the properties of copper-nickels and NABs in terms of localized corrosion and erosion- corrosion resistance. It also discusses the importance of correct commissioning and shut down procedures to ensure that the full capabilities of copper alloys are achieved.INTRODUCTIONAlongside gold, copper is the oldest metal used by man and its history of use dates back 10,000 years. Since antiquity both wrought and cast forms of copper alloys have shown high resistance to the ravages of the marine environment. Seawater is aggressive to most construction materials and, with properties which have been developed to meet today's exacting engineering challenges, copper alloys continue to offer reliable solutions to a range of seawater applications. Notable marine industries currently using copper alloys are commercial and naval shipping, thermal desalination, power generation and offshore oil and gas.Initially, copper was used for its availability, ease of fabrication and corrosion resistance. Additional properties, such as high thermal conductivity, excellent electrical conductivity and inherent high resistance to biofouling, became appreciated with time. Its facility to be easily alloyed with other elements such as tin, zinc, aluminum, lead, silicon, beryllium, iron, chromium and nickel led to a plethora of different alloys being produced providing a combination of improved strength, erosion- corrosion (impingement) resistance and galling resistance.