CORROSION 2002

ABSTRACT
Hydrogen permeation measurement by the collection method enables rapid detection of hydrogen emanation (efflux) from most carbon steel surfaces liable to be encountered in petrochemical production. In this paper the case is advanced for correlation of efflux data with corrosion rates, by conversion of data to an inferred hydrogen activity at the corroding face, ao, a parameter that is probably the best indicator of corrosive activity, independent of wall thickness and steel quality. This is used in evaluation of field data. Initial use of the hydrogen collection method has suggested widespread passivation of corrosion in cold sour systems, such that documented wall losses may occur as a result of only occasional and intense corrosion episodes. Conversely, in hot corrosive scenarios, inhibitors and corrosive scale are less effective in preventing a long term corrosive issue. Furthermore, above about 100 °C, 300 °F it is considered that hydrogen entry into steel can occur without the presence of a hydrogen promoter such as sour gas or hydrogen fluoride. Additionally, the permeability of steel to hydrogen increases sharply with temperature. This concurs with indications of high hydrogen permeation efflux associated with naphthenic acid corrosion.

INTRODUCTION
Hydrogen permeation monitoring has long been viewed as a prospective monitoring technique for various types of corrosion, particularly corrosion due to sour gas, H2S. A reliable and effective permeation measurement method is attractive in that it is completely non-destructive, and a measured flux (flow per unit area) of hydrogen emanating from a steel surface is directly evident of cathodic activity; since; at temperatures below 100 °C hydrogen does not enter and permeate steel due to any other cause.

In recent years the hydrogen collection method, has been developed (1~ and presented 1-3 which appears to offer extremely sensitive (pl/cm2/s), rapid (60 s) and reliable (+-10%) measurement of hydrogen efflux from steel over a wide range of steel curvature (down to (1) HydrosteelTM, marketed and manufactured by Ion Science Ltd, England 2" diameter piping) and surface temperature (up to at least 350 °C 4). In this paper we will present and discuss some preliminary corrosion measurements carried out in the field with this technology. First it is necessary to consider how effiux measurements can be used to infer hydrogen activity at the corroding interface.

ABSTRACT
Containment of spent nuclear fuel and vitrified forms of high level nuclear waste require use of materials that are highly corrosion resistant to all of the anticipated environmental scenarios that can occur in a geological repository. Ni-Cr-Mo Alloy 22 (UNS N60622) is proposed for the corrosion resistant outer barrier of a two-layer waste package container at the potential repository site at Yucca Mountain. A range of water compositions that may contact the outer barrier is under consideration, and a testing program is underway to characterize the forms of corrosion and to quantify the corrosion rates. Results from the testing support models for long term prediction of the performance of the container. Results obtained to date indicate a very low general corrosion rate for Alloy 22 and very high resistance to all forms of localized and environmentally assisted cracking in environments tested to date.

INTRODUCTION
The suitability of the Yucca Mountain is under investigation as the potential site for geological disposal of commercial nuclear spent fuel and some other forms of high- level nuclear waste in the United States. The site is located about 120 km northwest of Las Vegas in the state of Nevada on federally-owned land. The repository for the waste disposal would be constructed in a layer of tuff rock, known as the Topopah Spring member, at a depth approximately 300 meters below the earth's surface and about 300 m above the permanent water table at this location. The Yucca Mountain site is unique among potential repository sites under consideration in the different waste disposal programs throughout the world, since the waste would be emplaced in the unsaturated zone above the water table and in an environment that is fundamentally oxidizing in nature.

The purpose of this paper is to describe briefly the design of the waste package and the behavior of the proposed materials for nuclear waste containment. Because the long-term corrosion of the waste package materials is the paramount performance concern for containment of the waste package, an analysis of the expected corrosion performance occupies the main part of this paper. Last, the corrosion testing activities and modeling of the long term behavior based on results of the testing are discussed. The testing and modeling are on-going efforts, and it is expected that these activities will proceed for several more years into the future.

The overall strategy in isolating high-level nuclear waste is to make use of the natural barriers present in the host geology along with the construction of a series of engineered barriers. The waste package is an important component of the engineered barrier system. If the Yucca Mountain site is found suitable and recommended for a geological repository, two generic types of waste are planned for disposal there: (1) spent nuclear fuel from the commercial power reactors and from special DOE reactors. This waste is currently stored in many locations in the country. Assemblies of spent nuclear fuel would be delivered to the Yucca Mountain site, "as-is" from these storage locations. (2) reprocessed waste from defense programs and from commercial power reactors. At a few sites in the country, this reprocessed waste is converted into a borosilicate glass that is poured and molded in stainless steel canisters. These canisters would then be delivered to the Yucca Mountain site.

ABSTRACT
The protection of metals against corrosion by means of volatile compounds is the most progressive method of fighting metallic corrosion. These inhibitors are used to protect metallic articles and equipment during storage and transportation. In view of this we have synthesized six organic volatile corrosion inhibitors (VCIs) using Lauric hydrazide with various acids such as cinnamic acid, succinic acid, nitrobenzoic acid, phthalic acid and maleic acid and evaluated their inhibiting action on corrosion of mild steel, copper, brass, zinc and aluminium by weight loss and potentiodynamic polarization methods. All the investigated VCIs exhibited good inhibition efficiency for all the metals.

INTRODUCTION
The choice of a chemical compound as a vapour phase volatile corrosion inhibitor (VCI) depends on its vapour pressure and efficacy to prevent corrosion by forming a protective film. There are numerous investigations on corrosion inhibition by aliphatic amines, alicyclic amines and their salts as VCIs for various industrial metals and alloys 1-3. Amines of the fatty acid series are more effective than cyclic amines and aromatic amine 3, m-dinitrobenzene with 13- naphthol was examined as VCI in SO2 and chloride atmosphere by Rajagopalan et al. 4'5. Subramanian et al. 6 studied corrosion inhibitive performance of cyclohexylamine (CHA) salts and dicyclohexylamine (DCHA) salts on copper, mild steel and zinc in SO2 environment. DCHA exhibited 70.86, 85.15 and 91.81% inhibition efficiency (IE) in mild steel, copper and zinc respectively. Subramanian et al. 7 have recently studied the corrosion inhibition behavior of morpholine and its three salts such as morpholine carbonate, borate and phosphate. Of these, morpholine and its carbonate exhibited 90 and 85% IE, respectively, while other salts gave less than 40% IE

Continuing our recent work 8-9 on fatty acid derivatives as corrosion inhibitors, we report here the inhibiting properties of four organic vapour phase inhibitors (VCIs) namely, Lauric hydrazide (LH), Lauric hydrazide cinnamate (LHC), Lauric hydrazide nitrobenzoate (LHNB), Lauric hydrazide maleiate (LHM), Lauric hydrazide succinate (LHS) and Lauric hydrazide pthalate (LHP) on mild steel, brass copper, aluminium and zinc.

ABSTRACT
Scale inhibitor squeeze treatments are widely used to prevent scale in the near-wellbore region of the formation. In conventional squeeze treatments, a volume of brine containing a scale inhibitor is injected into the reservoir. When the well is produced, the scale inhibitor flows back in the produced water at low concentrations thus preventing scale formation.

Typically, scale inhibitor squeeze treatments are conducted in wells that have a significant water cut, providing excellent protection against the formation of scale deposits. However, in wells that have low water cuts or in wells completed to water-sensitive reservoirs, aqueous scale inhibitor treatments can cause serious problems that may result in lost or deferred production. Oil soluble scale inhibitor squeezes have been used recently in high oil cut wells in the North Sea to avoid many of the problems presented by water-based squeezes.

This paper describes the field implementation and results of a calcium sulfate scale removal treatment and subsequent oil soluble scale inhibitor squeezes into low water cut wells. For these wells, the treatments were designed to provide a technically and economically viable solution to a serious problem.

INTRODUCTION
Oilfield scales are the hard, adherent deposits formed when inorganic minerals dissolved in water precipitate during the production of oil and gas. Scale is typically formed when a change in the physical conditions, usually temperature and pressure, or composition of the water occurs, thereby disturbing the equilibrium. An example is the loss of dissolved carbon dioxide due to a pressure drop, in turn reducing calcium carbonate solubility.

ABSTRACT
Closed recirculating systems are used for cooling and heating tasks in buildings. Because their exposure to the atmosphere is limited, these systems do not have some of the problems of open recirculating (cooling tower) systems. Closed recirculating systems, however, do experience problems of corrosion, microbiological growth and fouling. Appropriate chemical and physical treatment can minimize these problems. Closed systems must be adequately monitored to determine treatment needs, control treatment programs and detect problems.

INTRODUCTION
Water is used in building heating and cooling systems for several good reasons. It is liquid over a wide temperature range, it holds and transfers heat efficiently and it is relatively "inert." Several types of closed recirculating water systems (loops) may exist in a building. These include chilled water loops, balancing hot (warm) water loops and hot water loops for building heating purposes. One of the most common is a closed chilled water loop that transfers heat from the environment to the evaporator section of a refrigeration chiller.

A "closed" system is defined by ASHRAE as a water system with no more than one point of interface with a compressible gas or surface. ~ This means that a system with an open or vented expansion tank is a closed system even though there is some contact with the atmosphere. An "open" system has more than one point of interface with the atmosphere. A cooling tower, for example, has points of contact with the atmosphere at the point the water is distributed in the upper basin and in the lower basin. Closed water systems that convey heat are often referred to as "hydronic" systems.

ABSTRACT
Stray-currents represent a significant problem for integrity of pipe-type cables. Pipe-type cables (feeders) are generally outfitted with impressed current cathodic protection (CP) systems and have an external coating. Unfortunately, the coatings are imperfect in that there are holidays and disbonded sites, and the effectiveness of CP system in the presence of stray current is difficult to measure. An approach to assess the effectiveness of cathodic protection in dynamic stray current conditions, consisting of monitoring the IR-drop free polarization (Eoff) potentials of multiple Coupon Test Stations (CTSs), buried in close proximity to the monitored feeder has proven to be successful. The CTSs act as a backbone for the Coupon Monitoring For Cathodic Protection Optimization (CMCPO) system, which performs a real-time analysis of the instant Eoff potentials, and zero-resistance ammeter currents downloaded from the individual CTSs, categorizes the existing corrosion conditions along the monitored structure according to a customizable algorithm, and uploads the solutions to the remotely controlled CP rectifiers. This system provides the ability to remotely monitor and control CP of pipelines in stray current areas more accurately than ever before. The paper offers quantitative assessment of the CMCPO system performance and benefits.

INTRODUCTION
Pipe-type cables (also known as feeders) have been used for electric power transmission since the 1930's. ~' 2 The largest number of cables of this type has been installed since the 1950's. These buried cable systems consist of the phase conductors, insulating material, a dielectric fluid for cooling and insulation, and an outer steel pipe. The pipe jacket is often coated with a dielectric coating for corrosion mitigation, and the cable is generally installed in a thermal insulating backfill (such as sand).

Despite the fact that the pipe-type cables are coated, industry experience with buried pipelines of all types has shown that coatings are not perfect. 3 The primary purpose of the coating is to provide a dielectric barrier between the steel substrate and the soil environment, which can sustain the corrosion process of the steel pipe. Flaws or pinholes in the coating, known as holidays, allow the metal substrate to be directly exposed to the soil electrolyte, thereby causing corrosion at that location.

Pipe-type cables are generally afforded corrosion control by cathodic protection (CP) in addition to protective coatings. The effectiveness of the cathodic protection systems in controlling corrosion of steel piping is predicated on proper operation and maintenance of the CP system, as well as monitoring to ensure that the minimum criterion for corrosion control is being met. However, despite installed CP systems, the pipe-type cables are reported to have experienced corrosion-related leaks. Feeder cables in complex utility environments can be subjected to stray currents as the result of the application of cathodic protection to foreign pipelines and stray currents emanating from sources such as DC transit systems. Stray current corrosion is a major contributor to the corrosion being experienced on the pipe-type cables.

ABSTRACT
Corrosion due to the impingement of particles is one mechanism causing erosion corrosion. Inhibitors can retard this corrosion. In this paper a method of estimating wear due to particle impingement is modified to include the effect of inhibitors. In laboratory experiments it is found that two inhibitors retard the effect of particle impingement. The results of the experiment are then used to assess the effect of using these inhibitors in field conditions with the new method of estimation.

INTRODUCTION
Erosion corrosion is a piping wear mechanism caused by flowing fluid disrupting or thinning the protective film of corrosion product. ~ The wear is caused by three major mechanisms" one is the chemical dissolution of the pipe, another is mechanical erosion caused by fluid flow while the third is due to the impingement of particles on the pipe wall. One guide for the design of offshore production platform piping systems has been the recommended practice guide of the American Petroleum Institute (API 14 RP E) .2 The guide calculates a velocity beyond which safe operation is not recommended. The basis and source of the velocity guidelines has been reviewed by Salama. 3 Different constants by various companies with the API 14 RP E criteria have been listed by Jordan.

In this work, the effect of inhibitors to reduce piping wear caused by the impingement of particles is considered. Three important papers have been written that show how operating and 456 environmental conditions affect erosion rates caused by the impingement of particles." The papers by Jordan and Mc Laury, Shirazi, Shadley and Rybicki contain factors that relate the corrosion rate due to particle impingement with elbow geometries, fluid velocities, fluid properties, particle diameters and densities and a constant that accounts for impact of the particle on a given material. The constant that accounts for impact of a particle on a given material varies with changes in sand sharpness, geometry, material hardness and an empirical factor that depends on piping material. Corrosion inhibitors have been observed to allow producers to produce at higher velocities. 7'8'9 In this paper, laboratory results on the ability of a corrosion inhibitor to reduce the corrosion due to particle impingement are presented. The experiments were performed in a rotating cage apparatus similar to the slurry pot tester used by Clark. ~° The laboratory results are then used to determine a modified constant for the impact of a particle on the pipe when corrosion inhibitor is present. The possible ability to increase production for a given configuration of piping while avoiding erosion corrosion is then investigated.

ABSTRACT
A convenient protocol for screening the potential efficacy of scale inhibitors is described. All of the techniques used require relatively inexpensive equipment. Two types of scale are addressed in this paper, calcium carbonate and calcium oxalate, but the general procedures are expected to be applicable to inhibitor screening for others as well. The screening tests used include a turbidity/light scattering method that requires only a simple spectrophotometer. Another simple measurement was the hot surface deposition of scale formed in situ from hot solutions utilizing heating elements with matched heat fluxes. In addition, it was found that conventional optical microscopy can provide valuable information concerning the ability of scale inhibitor candidates to disrupt nascent crystal symmetry and generate particulate geometries that are amenable to dispersion (rather than surface deposition). These experimentally convenient procedures provide information that is of value in assessing the potential of various chemical moieties to inhibit harmful scale and/or deposition development.

INTRODUCTION
The many adverse consequences of the deposition of crystalline scale and/or amorphous deposits on heat transfer surfaces have been well known for many years. Indeed, treatments to try to minimize such occurrences were already being described in the 19 th century. It is beyond the scope and intent of this communication to provide a history of these developments and the references provided in this communication provide examples of the types of work done but by no means do they present a comprehensive review. Suffice it to say that after all of these years the effort to prevent or at least decrease scale/deposit formation on surfaces still continues and its importance has not diminished. The "battle" is particularly interesting from a technical point of view because there are a variety of scales and precipitates over which control is attempted and different industries have their own special "culprits". Examples include calcium sulfate in oil drilling operations ~, calcium carbonate in boilers and cooling systems 2, and the formation of calcium oxalate in paper mill operations 3.

There are many approaches taken to control scale formation 4. Examples include the use of chelants or sequestrants to complex metallic ions involved in scale formation, and threshold inhibitors that function to prevent scale and/or precipitate formation via surface deactivation when present in substoichiometric quantities (relative to the potential amount of scale that could form in a given system). The newer threshold inhibitors frequently offer the additional advantage of functioning as effective dispersants so that other solids (scale-like precipitates and other solid contaminants that may be introduced into a particular system) remain dispersed in the liquid and don't "plate out" onto surfaces.

ABSTRACT
Zircaloy (-2 and -4) spent nuclear fuel cladding is considered by the U. S. Department of Energy as an additional metallic barrier for the containment of radionuclides in the proposed repository at Yucca Mountain, Nevada. Because Zircaloy develops a thick oxide during in-reactor service, hydrothermally oxidized Zircaloy was compared to as-polished Zircaloy under a variety of environmental conditions to evaluate the effect of the oxide film on localized (pitting) corrosion in chloride-containing solutions. Besides cyclic potentiodynamic polarization and potentiostatic tests, open circuit potentials measurements were conducted in air saturated chloride solutions with the addition of H2O2 and FeCl3. The electrical characteristics of the hydrothermally grown oxide films were examined using electrochemical impedance spectroscopy and measurements of the charge transfer resistance for a redox couple. Stable pitting corrosion in the presence of a thick oxide layer was observed after 40 days in potentiostatic tests but it was not initiated in open circuit tests. Preliminary explanations for this observation are provided.

INTRODUCTION
A large portion of the commercial spent nuclear fuel to be disposed in the proposed repository at Yucca Mountain, Nevada, is clad with Zircaloy-2 (Zr-2)(1) or Zircaloy-4 (Zr-4)(2). These two Zr-1.5%Sn alloys contain Fe, Cr, and Ni as minor alloying elements but differ in that the Ni content is much lower in Zr-4 to decrease the hydrogen pick-up as a result of corrosion in high temperature water. For this reason, Zr-4 is used in pressurized water reactors (PWRs) whereas Zr-2 is used for boiling water reactor (BWR) fuel cladding. The U.S. Department of Energy (DOE), in its performance assessment of the proposed repository, has assumed that Zr-2 or Zr-4 cladding an additional metallic barrier to radionuclide release.

Zr alloys, and in particular Zr-2 and Zr-4, exhibit exceptional corrosion resistance in a variety of aqueous solutions over a wide range of pHs and temperatures due to the formation of a protective passive film composed of ZrO2. However, Zr and its alloys are known to be susceptible to various degradation modes as a result of aqueous corrosion that may lead to the failure of fuel cladding under disposal conditions, including general corrosion, localized corrosion, and stress corrosion cracking. Of the species expected to be present in the groundwater at Yucca Mountain, chloride and fluoride anions are considered to likely to have the most significant effect on localized corrosion of Zr- 2 or Zr-4.

In previous work,2 we have examined the general and localized corrosion of as-polished Zr-4 in an attempt to try to understand the possible failure modes that may be encountered in the proposed repository at Yucca Mountain. It was observed that pitting corrosion occurs in both neutral and acidic chloride solutions above a critical potential. As reviewed elsewhere, 3 the critical potential for pitting initiation measured using potentiostatic techniques combined with mechanical disruption of the passive film by straining and scratching coincides with the repassivation potential (Erp). Erp also exhibits a linear dependence with the logarithm of the chloride concentration. Zircaloy cladding, however, undergoes significant oxidation while in service and the behavior of aspolished material may not be representative of actual cladding. For example, the oxide film on spent nuclear fuel cladding typically has a thickness ranging from 10 to 60 µm as a result of oxidation during the fuel cycle under reactor operating conditions.4 Thus, the purpose of this work was to examine the localized corrosion of hydrothermally oxidized Zr-4 under conditions similar t

ABSTRACT
This report summarizes the results of an effort to identify effective, now-term, environmentally compliant corrosion prevention and control processes for Air Force ground-based vehicles (AFGBV) that could be integrated at both organizational and depot levels. This report is a comprehensive discussion of the results of this project, alternate coating systems, and the effects of corrosion on untreated surfaces. Additionally, corrosion problems noted throughout this report are not relegated to one particular model, design, or series of vehicles but to the vehicle fleet as a whole. Therefore this report will not attempt to categorize corrosion prone vehicles but will address specific concerns in vehicle design and maintenance.

INTRODUCTION
Corrosion continues to pose a readiness problem within the Department of Defense (DoD). The direct cost of corrosion maintenance and repair to the United States Air Force vehicles exceeds $24 million dollars annually ~. Currently, the AFGBV fleet located in or operating in moderate to severe corrosion prone locations are experiencing significant corrosion within months of delivery to the organization. This corrosion, if left untreated or improperly treated, ultimately results in premature structural failure, more downtime for maintenance, and condemnation of the vehicle prior to the end of its expected service life.