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Abstract During the past three years, we have been working on the development of a liquid applied coating solution to provide protection against Corrosion Under Insulation (CUI). It was evident that different types of coatings showed different behaviour depending of the test methods used. We found particularly challenging to use the results of accelerated testing to predict field performance. Although there are some standards or guides for specifying coatings for CUI protection (NACE SP 0198-2010, NORSOK M501 ed. 6) there is lack of broadly accepted methods of test. The current standards do not necessarily agree on what the optimum solution is. Furthermore, the existing knowledge is habitually kept inside coating manufacturers and the full picture of the performance evaluation of CUI coatings is not always well understood. This paper is an account of the problems, challenges and solutions that we have found during the development of a liquid coating solution to provide protection against CUI, and the lessons that can be extracted in order to facilitate future developments in the field. Introduction Corrosion Under Insulation (CUI) is defined as a severe form of corrosion due to entrapped water and electrolytes under the thermal insulation layer of piping and vessels. On carbon steel CUI can take place in the form of general corrosion or localised corrosion. CUI is extremely critical since it takes place out of sight and may cause costly unexpected shut downs and catastrophic accidents. Protection against Corrosion Under Insulation (CUI) is a relatively novel and evolving area of knowledge. Protective coatings are an important method of corrosion control in reducing or preventing CUI. There has been progress since 2004, when Fitzgerald suggested the use of organic coatings up to around 100°C and other more costly solutions like thermal spray aluminium and Al-foil wrapping for higher temperatures. The use of epoxies has been extended to higher temperatures and new coating technologies have entered the market, in particular high build silicones.
- Well Completion > Well Integrity > Subsurface corrosion (tubing, casing, completion equipment, conductor) (1.00)
- Production and Well Operations > Production Chemistry, Metallurgy and Biology > Corrosion inhibition and management (including H2S and CO2) (1.00)
- Facilities Design, Construction and Operation > Pipelines, Flowlines and Risers > Materials and corrosion (1.00)
Abstract Discrete galvanic anodes are used to minimize the ring/incipient/halo anode effect in concrete repairs relying on sacrificial corrosion of a more active metal than conventional reinforcing steel to provide continued protection. The demand for this protection changes with time based on the corrosion activity of the steel requiring protection. When the concrete is repaired, the repair material creates a strongly cathodic area within the repair that accelerates corrosion in the reinforcing steel immediately adjacent to the repair area known as the ring or incipient anode or halo effect. This requires an initially high current flow from the discrete galvanic anode that decreases with time. New “hybrid technology” anodes uses a short interval of impressed current cathodic protection to create a passive condition in the halo area to move halides away from the reinforcing steel and restore alkalinity to the concrete in contact with the reinforcing steel. Following this impressed current treatment, protection is maintained through galvanic activity of zinc after the impressed current is removed. A novel “bimetallic” technology has been developed using two active galvanic metals, magnesium and zinc. A small amount of magnesium can provide the "jump start" to create an initial high polarization similar to these other hybrid anodes without the need of external power, rewiring of the cathodic protection system or reliance on complex electrical circuitry to control the impressed current phase of treatment. The new bi-metallic anode is simply installed exactly like conventional single stage anodes. Following consumption of the magnesium, maintenance current is provided by conventional zinc galvanic protection. Furthermore, because the galvanic reaction is controlled by the environmental conditions of the installation and corrosion activity of the reinforcing steel, there is no potential for overvoltage, complex wiring, or any additional activity required after the hybrid anode is installed.
- Materials (1.00)
- Energy > Oil & Gas > Upstream (1.00)
- Government > Regional Government > North America Government > United States Government (0.47)
- Well Completion > Well Integrity > Subsurface corrosion (tubing, casing, completion equipment, conductor) (1.00)
- Reservoir Description and Dynamics (1.00)
- Production and Well Operations > Production Chemistry, Metallurgy and Biology > Corrosion inhibition and management (including H2S and CO2) (1.00)
- Facilities Design, Construction and Operation > Pipelines, Flowlines and Risers > Materials and corrosion (1.00)
Abstract Corrosion control of on-grade petroleum products storage tank bottoms is a statutory requirement for Oil and Gas Operators worldwide. Tank bottoms are susceptible to corrosion attacks due to their direct contact with soil, moisture and other corrosive elements within the tank foundation. When such failures occur, the consequences are enormous including serious environmental pollution and damages resulting from seepage of petroleum products into the service environment. Cathodic Protection System in addition to good materials selection and coating applications are global industrial practice for corrosion prevention of on-grade tank bottom plates. This paper therefore discusses an effective and efficient impressed cathodic protection system by laying a continuous shallow anodesbed in close proximity to the tank foundation. Some of the merits of this installation include elimination of shielding effects or interference from other structures and uniform protection of the entire tank bottom. The technique will also eliminate the possibilities of underprotection which could lead to localized corrosion failures within the system. Introduction Government and industrial regulations, environmental and economic issues make corrosion control of on-grade petroleum products storage tanks very essential. Over the years, thousands of petroleum products storage tank bottoms have developed failures resulting in their contents seeping into the environment. The consequence of .such seepage depends on products characteristics and nature of service environment. Quite often, corrosion activities are responsible for the failures found on tank bottom plates. This phenomenon is due to the presence of corrosion elements within the tank foundation. Corrosion is experienced commonly at the voids or vapour spaces between the metal tank bottom plates and the foundation surface. Occurrence of these vapour spaces could be due to the flexing up and down of tank bottom plates at empty and filled-up conditions respectively.
- Africa > Nigeria (0.30)
- North America > United States > Texas (0.21)
Abstract This paper aims to present innovative solutions in which organic composite materials can be utilized for solving corrosion problems. A solution is presented for corrosion protection of flanged coupling external protection. Flanged pipework is widely used in the industry. The operating environment can lead to external corrosion, metal loss, and flange bolt seizing among others. These problems cause plant shutdowns, waste of valuable resources, and efficiency reduction not to mention costly maintenance expenses. To overcome these actual concerns in an innovative way, this paper presents flanged coupling external solutions. By using a flexible and peelable elastomeric material, flanged couplings and pipework can be isolated from corrosive environments, peeled off if required, inspected, and resealed. With this practical solution, this paper will enable material selection engineers to make an informed decision regarding corrosion protection strategies for flanged pipework in harsh environments. Introduction Flanges are pieces of equipment used for joining pipe sections and other pipe fittings such as valves, together. The fluid in the pipe could be a liquid, gas or slurry depending on the industry. The carbon steels are among the most common materials of construction and probably account for 80% of all vessels used in the industry. Towers, heat exchangers, separators, storage tanks, piping, and most structures are generally fabricated from carbon steel. Flanges are not the exception. However, carbon steel as other conventional materials corrodes if exposed to electrolytes. The actual design of flanges means that they are particularly susceptible to corrosion. The void between the flange faces can readily trap moisture leading to crevice corrosion. The use of dissimilar metals, for example for the fastenings, can lead to galvanic corrosion. Weld areas will typically be rough and can trap moisture. Obviously, the rest of the external surfaces of the flange and connected pipe, which are also made of carbon steel, will therefore corrode.
- Overview > Innovation (0.48)
- Research Report (0.32)
- Well Completion > Well Integrity > Subsurface corrosion (tubing, casing, completion equipment, conductor) (1.00)
- Production and Well Operations > Production Chemistry, Metallurgy and Biology > Corrosion inhibition and management (including H2S and CO2) (1.00)
- Facilities Design, Construction and Operation > Pipelines, Flowlines and Risers > Materials and corrosion (1.00)
Abstract The design rules used to design CP systems in the main do not take into account the interference between the anodes provided to protect a structure or interactions between the structures themselves. CP systems will always interact with each other to some extent when they are in the same electrolyte even when there is no metallic electrical connection and this can radically affect the protection provided to the structure and the life of the CP system. A case study is presented involving the design of the CP system of an FPSO (Floating production storage and offloading vessel). The aim of the study was to verify the performance of the CP system to ensure that the structure was protected for the design life and the anodes had sufficient capacity. Computer modelling was used to simulate the performance of the CP system which comprised of an ICCP system and sacrificial anodes. The study identified some interesting and unexpected interactions which required the design of the CP system to be modified. Introduction Interference can significantly affect the performance of Cathodic Protection (CP) systems designed to protect structures from corrosion. There are many forms of interference which the CP Engineer has to consider and mitigate the effect of, if the CP design is to perform as required over the life of the structure. For example: • Anode interference can significantly degrade the ability of the anodes to supply the required current • Interference can occur between structures protected by CP systems • External electrical sources can also cause interference particularly for onshore pipelines and tanks This effect of anode interference can be most clearly seen when anodes are closely grouped for example around a monopile or an anode sled where the effective output of the anodes can be radically reduced when compared to the classical anode resistance calculations. For example the effective anode output of an anode sled can be reduced by 80% simply by the way in which the anodes are arranged. In order to accurately determine the anode configuration required to protect the structure, computer modelling is necessary because the classical anode resistance formulas are not applicable.
Abstract Non-ferrous metals and alloys such as aluminum, copper, and brass are frequently used for a wide range of applications in several industries, including the automotive and electronics industries. Under ambient conditions, these metals are protected from corrosion by passivating oxide layers. However, when in contact with corrosive media, such as alkaline water-based metalworking fluids, they require additional protection in the form of a corrosion inhibitor. This study will investigate the performance of non-ferrous metal corrosion inhibitors in metalworking fluids and other water-based systems. It will explore how different chemistries perform on different metal substrates and will examine the advantages and disadvantages of these chemistries. Introduction Aluminum alloys are widely used in the aerospace, automotive, and electronics industries, as they are durable, lightweight, and easily formed. However, developing water-based machining fluids for aluminum can be difficult due to the propensity of such fluids to stain the aluminum surface. Although aluminum has good corrosion resistance in aqueous solutions with neutral or near-neutral pH values due to the passivating aluminum oxide layer that forms on its surface, this protective oxide layer is amphoteric and will dissolve in both highly acidic and highly alkaline solutions, leaving the aluminum surface vulnerable to staining. Metalworking fluids are typically formulated to be alkaline (pH of 9.0-9.5) in order to protect ferrous metals and to reduce biological activity. Alkanolamines are commonly used to raise the pH of the fluid and to act as surfactants; these molecules can further promote staining on aluminum. Providing corrosion protection for aluminum within a metalworking fluid package is therefore of especial importance. A variety of corrosion inhibitors have been used to prevent aluminum corrosion in alkaline solutions. While many inorganic silicates offer good corrosion protection4, they sometimes precipitate out of solution at a pH below 11, limiting their effectiveness. In addition, silicates are largely incompatible with soluble oil-based metalworking fluids due to hydrolysis. Inorganic polyphosphates were found to offer similar corrosion protection; however, the high phosphorus content of the resulting formulations can lead to problems with water pollution. Organic phosphate and phosphonate esters provide excellent protection with lower phosphate content, and are widely used in aluminum machining fluids. In addition, some studies have shown that carboxylates can inhibit the corrosion of aluminum in mildly alkaline solutions. These results suggest that carboxylates could also be of use in alkaline metalworking fluids.
- Water & Waste Management > Water Management > Water & Sanitation Products (1.00)
- Materials > Chemicals > Specialty Chemicals (1.00)
- Well Completion > Well Integrity > Subsurface corrosion (tubing, casing, completion equipment, conductor) (1.00)
- Production and Well Operations > Production Chemistry, Metallurgy and Biology > Corrosion inhibition and management (including H2S and CO2) (1.00)
- Facilities Design, Construction and Operation > Pipelines, Flowlines and Risers > Materials and corrosion (1.00)
Abstract There have been many instances of Corrosion Under Insulation (CUI) in the Gulf of Mexico (GoM) and worldwide. On most sites, CUI tends to be a medium to long-term phenomenon with the risk of CUI increasing significantly after a 5 to 10 year service, but can occur well before this. A lack of appreciation of the impact on the type of insulation used, the proper application and maintenance /repair, combined with regular testing firewater deluge systems, water leaking from poor connections in adjacent pipework, severity of the prevailing weather conditions, or simply due to the general environment like offshore, can often lead to CUI failures earlier than could otherwise have been envisioned. In order to reduce the likelihood of CUI under traditional typical types of insulation, proper insulative coatings can be used instead where applicable. The objective of this study was to evaluate five insulative coating systems applied to several test panels to determine which system(s) are most suitable for GoM offshore applications. These systems were applied according to manufacturers’ procedures, on similar panels, applied by the same applicator, on the same day. The systems were evaluated by a third party independent laboratory to determine their performance. The lab evaluation program included the following tests on various selected insulating coatings; temperature reduction tests, corrosion mitigation tests, impact and adhesion test, moisture permeability, ease of application, ability to inspect metal substrate under coating and thermal cycle cracking resistance tests. The testing procedures and test results are discussed in this paper. Introduction Offshore Oil & Gas Production facilities in the Gulf of Mexico have hot pipes and vessels which need thermal insulation and corrosion protection. The traditional method is to apply protective coatings on steels, overwrapped with a thick layer of insulation material, (e.g. mineral wool, fiberglass, etc.) and then sealed with metal jacketing. However, severe corrosion under insulation (CUI) issues have been discovered after some year service. The CUI has become a widespread industry concern. One of the issues is not able to inspect the corrosion easily without removing the metal jacketing and insulation materials. Recently, a new class of insulative coating system became available as an alternative to the traditional thermal insulation system. The new insulative coating system uses a primer and overcoat with the waterborne acrylic coating filled with hollow glass microspheres or Silica Aerogel?.
- Well Completion > Well Integrity > Subsurface corrosion (tubing, casing, completion equipment, conductor) (1.00)
- Production and Well Operations > Production Chemistry, Metallurgy and Biology > Corrosion inhibition and management (including H2S and CO2) (1.00)
- Facilities Design, Construction and Operation > Pipelines, Flowlines and Risers > Materials and corrosion (1.00)
Abstract A seachest is a void space or box on the body of a marine vessel below the water line from which piping systems draw raw water for cooling or other uses such as ballasting of the vessel and fire-fighting. The inlet grid or intake of the seachest, which is protected by a grating, can vary in size from under 1 sq. meter for a small inland tug to several hundred sq. meters for a large vessel like an oil tanker. The seachest is normally fabricated from carbon steel like the rest of the vessel, while the adjoining piping and valves are nonferrous. Zinc anodes in combination with coatings are used for the corrosion protection of the ship’s hull as well as the seachest. A waster-sleeve, typically fabricated from 0.375-inch (9.52 mm) thick carbon steel plate, is recommended as additional sacrificial protection for the non-ferrous components with a projected service life of 10-12 years or more. Since the waster sleeves (as well as adjoining non-ferrous components) are electrically continuous to each other, they also receive some protection from the zinc anodes. Replacement of waster-sleeves is a high cost item. Depending on the size of the waster-sleeves, dry-dock replacement installation can cost anywhere from $5,000 to $25,000 while underwater installations can be as much as $200,000. Hence, early failure of these and other seachest components can seriously impact the extended life cycle goals for these vessels. During the nineties, premature failure of waster-sleeves were observed on a number of ocean-going vessels. Based on shipyard surveys of failed waster sleeves it was found that the standard thickness of 0.375 in (9.52 mm) was not sufficient to survive the desired 12-year service life and even doubling the thickness only had marginal effect. Engineering analysis indicated that the existing CP design utilizing only 2 to 4 pieces of 42-lb (19.1 Kg) Zn anodes was inadequate and a re-designed CP system with a larger number of anodes would possibly solve the problem.
- Transportation > Marine (1.00)
- Materials > Metals & Mining > Steel (0.90)