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OPITO GLOBAL ##: OIL & GAS TRAINING CERTIFICATE An Introduction to Physical Science and Basic Properties of Materials OGTS M12 Presenter: Otim Robert HSE and Protocols for the Course 24 June 2019 / ‹#› ❑Alarms...
OPITO GLOBAL ##: OIL & GAS TRAINING CERTIFICATE An Introduction to Physical Science and Basic Properties of Materials OGTS M12 Presenter: Otim Robert HSE and Protocols for the Course 24 June 2019 / ‹#› ❑Alarms and Escape Routes ▪There are no planned alarms ▪Any alarm must be treated as ‘live’ ▪Leave the room in an orderly manner ▪Proceed to the Muster Point ▪Await further instructions ❑Mobile Phones ▪Please turn them off ▪If you are ‘On Call’ turn to Vibrate ▪Please leave room to answer ▪Please decline social calls ❑Comfort Breaks ▪We will take a 15 minute break every 1.5 hour ▪Please return promptly so we can finish on time Learning Activity Objectives: Upon completion of this course, participants should be able to: 1. Outline the basic principles of matter and atomic structure in an engineering context 2. Outline the basic properties of materials in an engineering context 3. Outline the basic properties of mechanics in an engineering context 4. Carry out simple mechanics calculations in an engineering context LO.1 Outline the basic principles of matter and atomic structure in an engineering context Here we shall look at: P1.1 Identify phase changes and the basic properties of solids, liquids and gases P1.2 Describe the basic concept of atomic structure P1.3 Identify the key principles of the periodic table of elements P1.4 Describe the basic principles of elements and compounds LO.1 Outline the basic principles of matter and atomic structure in an engineering context P1.1 Identify phase changes and the basic properties of solids, liquids and gases Matter ▪ Matter is any substance that has mass and takes up space by having volume ▪ All everyday objects from the chair you're sitting on to the air you breathe are ultimately composed of atoms. ▪ These atoms consist of interacting subatomic particles (such as protons, neutrons, and electrons). ▪ Matter exists in various states (also known as phases). ▪ These phases include solid, liquid, and gas – for example water exists as ice, liquid water, and gaseous steam. LO.1 Outline the basic principles of matter and atomic structure in an engineering context P1.1 Identify phase changes and the basic properties of solids, liquids and gases Phases of Matter Different phases of matter behave in unique ways. ▪ In a solid, attraction between particles is greater than their energy of motion , particles are also close. Thus they form a definite shape ▪ In liquids, particles are close but their energy of motion and attraction are about the same. They have no definite shape and therefore form the shape of the container. ▪ Gas particles are far apart and their energy of attraction is less than their energy of motion. They have shape and can expand or compressed to fill the container LO.1 Outline the basic principles of matter and atomic structure in an engineering context P1.1 Identify phase changes and the basic properties of solids, liquids and gases Phase Differences ▪ Ice, liquid water and water vapor may consist of the same molecules, but they differ in several important ways. ▪ For example, it's difficult to compress a solid or liquid to a large degree, but you can easily compress a gas. ▪ Liquids and gases assume the shape of their containers, but solids do not. Gases have an additional ability to expand when they assume a container's shape and match the container's volume. LO.1 Outline the basic principles of matter and atomic structure in an engineering context P1.1 Identify phase changes and the basic properties of solids, liquids and gases Phase changes LO.1 Outline the basic principles of matter and atomic structure in an engineering context P1.1 Identify phase changes and the basic properties of solids, liquids and gases Phase Transitions Factors affecting phase transitions ▪ Temperature, ▪ Pressure and ▪ Substance's composition A phase diagram shows the phases that different substances assume at various temperatures and pressures. The generalized phase diagram for a pure material as a function of temperature (T) and pressure (p). LO.1 Outline the basic principles of matter and atomic structure in an engineering context ▪ P1.1 Identify phase changes and the basic properties of solids, liquids and gases Phase Diagram ▪ The pressure–temperature phase diagram of carbon dioxide (CO2) ▪ At atmospheric pressure (~100kPa), the solid converts directly to vapor ▪ At a temperature of 194.7 K; this can be seen in the sublimation of dry ice, CO2(s) LO.1 Outline the basic principles of matter and atomic structure in an engineering context P1.2 Describe the basic concept of atomic structure ATOM ▪ An atom is the smallest unit of matter that retains all of the chemical properties of an element. ▪ Atoms combine to form molecules, which then interact to form solids, gases, or liquids. For example, water is composed of hydrogen and oxygen atoms that have combined to form water molecules. LO.1 Outline the basic principles of matter and atomic structure in an engineering context P1.2 Describe the basic concept of atomic structure ATOMIC STRUCTURE ▪ The atomic structure of an element refers to the constitution of its nucleus and the arrangement of the electrons around it. Primarily, the atomic structure of matter is made up of protons, electrons and neutrons. ▪ The protons and neutrons make up the nucleus of the atom, which is surrounded by the electrons belonging to the atom. ▪ The atomic number of an element describes the total number of protons in its nucleus. ▪ Neutral atoms have equal numbers of protons and electrons. However, atoms may gain or lose electrons in order to increase their stability, and the resulting charged entity is called an ion. ▪ Atoms of different elements have different atomic structures because they contain different numbers of protons and electrons. This is the reason for the unique characteristics of different elements. LO.1 Outline the basic principles of matter and atomic structure in an engineering context P1.2 Describe the basic concept of atomic structure ATOMIC STRUCTURE RUTHERFORD BOHR You can read about atomic models for more understanding LO.1 Outline the basic principles of matter and atomic structure in an engineering context P1.2 Describe the basic concept of atomic structure ATOMIC STRUCTURE ▪ Atomic Mass ▪ Protons and neutrons have approximately the same mass, about 1.67 × 10-24 grams. Scientists define this amount of mass as one atomic mass unit (amu) or one Dalton. ▪ Although similar in mass, protons are positively charged, while neutrons have no charge. ▪ Therefore, the number of neutrons in an atom contributes significantly to its mass, but not to its charge. ▪ Electrons are much smaller in mass than protons, weighing only 9.11 × 10-28 grams, or about 1/1800 of an atomic mass unit. Therefore, they do not contribute much to an element’s overall atomic mass. ▪ When considering atomic mass, it is customary to ignore the mass of any electrons and calculate the atom’s mass based on the number of protons and neutrons alone. LO.1 Outline the basic principles of matter and atomic structure in an engineering context P1.3 Identify the key principles of the periodic table of elements Periodic Table ▪ Periodic table, in chemistry, is the organized array of all the chemical elements in order of increasing atomic number—i.e., the total number of protons in the atomic nucleus. ▪ Element symbol: – An abbreviation for the actual name of the element. ▪ Atomic Number: – The atomic number represents the number of protons within the nucleus. It also indicates the charge number. ▪ Atomic mass: – This is the number of protons, electrons and neutrons present within the atom of the element ▪ When the chemical elements are thus arranged, there is a recurring pattern called the “periodic law” in their properties, in which elements in the same column (group) have similar properties. The initial discovery, which was made by Dmitry I. Mendeleev in the mid-19th century, has been of inestimable value in the development of chemistry. LO.1 Outline the basic principles of matter and atomic structure in an engineering context P1.3 Identify the key principles of the periodic table of elements Principles of the periodic table ▪ Periods (rows): The elements are arranged in seven horizontal rows, known as periods, in order of increasing atomic number from left to right and top to bottom. Each period corresponds to a different electron shell or energy level. ▪ Groups (Columns): The vertical columns on the periodic table are called groups. Elements within the same group exhibit similar chemical properties. There are 18 groups (numbered 1–18 from left to right). The main group elements are in groups 1, 2, and 13–18, while groups 3–12 contain the transition elements. The two rows at the bottom are the lanthanides and actinides. The periodic table classifies elements into three main categories: - Metals: Good conductors of electricity and heat, ductile, malleable, and lustrous. - Nonmetals: Typically lack metallic properties. - Semimetals: Exhibit properties intermediate between metals and nonmetals. - https://www.youtube.com/watch?v=uPkEGAHo78o&t=609s LO.1 Outline the basic principles of matter and atomic structure in an engineering context P1.3 Identify the key principles of the periodic table of elements LO.1 Outline the basic principles of matter and atomic structure in an engineering context P1.3 Identify the key principles of the periodic table of elements LO.1 Outline the basic principles of matter and atomic structure in an engineering context P1.4 Describe the basic principles of elements and compounds Elements ▪ An element is the simplest (can’t be broken down into a simpler substance)form of matter that has a unique set of properties. Examples include oxygen, iron, and gold etc.. Likewise, one element cannot be chemically converted into a different element. ▪ Some elements have been known for centuries (gold, silver, iron, and copper among others) while others have been created in the lab only within the last several years. Compounds ▪ A compound is a substance that contains two or more elements chemically combined in a fixed proportion. ▪ For example carbon and hydrogen combine to form many different compounds. ▪ One of the simplest is called methane, in which there are always four times as many hydrogen particles as carbon particles. Methane is a pure substance because it always has the same composition. However, it is not an element because it can be broken down into simpler substances - carbon and hydrogen. LO.1 Outline the basic principles of matter and atomic structure in an engineering context P1.2 Describe the basic concept of atomic structure COMPOUND ▪ (A) Sodium is so reactive that it must be stored under oil. ▪ (B) Chlorine is a poisonous yellow-green gas. ▪ (C) Salt crystals, a compound of sodium and chlorine. Prepared Washington.M.Kafesu LO.1 Outline the basic principles of matter and atomic structure in an engineering context P1.4 Describe the basic principles of elements and compounds COMPOUNDS ▪ Recall that the components of a mixture can be separated from one another by physical means. This is not true for a compound. Table salt is a compound consisting of equal parts of the elements sodium and chlorine. Salt cannot be separated into its two elements by filtering, distillation, or any other physical process. Salt and other compounds can only be decomposed into their elements by a chemical process. ▪ The properties of compounds are generally very different than the properties of the elements from which the compound is formed. Sodium is an extremely reactive soft metal that cannot be exposed to air or water. Chlorine is a deadly gas. The compound sodium chloride is a white solid which is essential for all living things LO.2 Outline the basic properties of materials in an engineering context P2.1 Identify the key features and mechanisms of wear and corrosion P2.2 Describe the key features of the concepts of density, reactivity and magnetism P2.3 Describe the key features of electrical and thermal conductivity of materials P2.4 Describe the key features of the concepts of hardness, ductility, plasticity, toughness and malleability LO.2 Outline the basic properties of materials in an engineering context P2.1 Identify the key features and mechanisms of wear and corrosion Material Deterioration ▪ All materials suffer deterioration under certain conditions of service or certain environments, which must be avoided to prolong their useful life to the maximum. ▪ It is important to know why certain materials tend to be stable (or unstable) in certain environments. ▪ Deterioration is related to the structure, properties and processing of different materials.. LO.2 Outline the basic properties of materials in an engineering context P2.1 Identify the key features and mechanisms of wear and corrosion Material Wear ▪ Wear is the removal of the material from the surface of a solid body as a result of mechanical action of the counterbody.. ▪ Wear may combine effects of various physical and chemical processes proceeding during the friction between two counteracting materials: micro-cutting, micro-ploughing, Plastic deformation, cracking, fracture, welding, melting, chemical interaction. ▪ The result of wear is the loss of material and the subsequent decrease in dimensions and therefore the loss of tolerances LO.2 Outline the basic properties of materials in an engineering context P2.1 Identify the key features and mechanisms of wear and corrosion Material Wear ▪ Wear is very important in engineering practice Effects of cavitation ▪ In many cases, it is the main factor that limits on an impeller the life and performance of machine components. ▪ Example: a fully worn 5-ton truck usually weighs between two and three kilograms less than when new. ▪ No machine element is immune to wear; This phenomenon manifests itself whenever there is load and movement. ▪ Example: piston wear in internal combustion engines, pitting and cracking in transmission gears, etc., are signs of wear. LO.2 Outline the basic properties of materials in an engineering context P2.1 Identify the key features and mechanisms of wear and corrosion Material Damage ▪ Damage mechanisms in materials are mainly due to plastic deformation, crack formation and propagation, corrosion and/or wear. ▪ Criteria to prevent or combat wear: – Keep contact pressure low – Keep sliding speed low – Keep bearing surfaces smooth – Use hard materials – Ensure low coefficients of friction ▪ Use lubricants. LO.2 Outline the basic properties of materials in an engineering context P2.1 Identify the key features and mechanisms of wear and corrosion Material Wear types ▪ Wear can be caused by contact with: – Other metal (adhesive wear), – A metallic or a non-metallic abrasive (Abrasive Wear), – Liquids or gases in movement (erosion and cavitation) – Fatigue wear – Corrosive wear ▪ Wear involving a single type is rare, and in the In most cases, abrasive wear and adhesive LO.2 Outline the basic properties of materials in an engineering context P2.1 Identify the key features and mechanisms of wear and corrosion Material Wear types ▪ Main wear mechanisms a) adhesive wear b) abrasive wear c) fatigue wear, and d) erosive wear LO.2 Outline the basic properties of materials in an engineering context P2.1 Identify the key features and mechanisms of wear and corrosion Material Wear types ▪ Each form of wear is affected by a variety of conditions: – Ambient – Type of applied load, relative speeds of the parts that are coupled – Lubricant – Temperature – Hardness – Surface finish – Presence of foreign particles – Composition – Compatibility of the coupling parts involved LO.2 Outline the basic properties of materials in an engineering context P2.1 Identify the key features and mechanisms of wear and corrosion A. Adhesive Wear ▪ Adhesive wear occurs when two nominally flat solid bodies are in sliding contact, whether or not they are lubricated. ▪ Adhesion occurs at the asperity/sharpness contacts at the interface. These contacts are sheared by relative motion, which may result in detachment of a fragment from one surface and attachment to the other. Magnified view of two friction surfaces LO.2 Outline the basic properties of materials in an engineering context P2.1 Identify the key features and mechanisms of wear and corrosion Adhesive Wear Mechanism ▪ Adhesive wear mechanism: – a) Before contact – b) During contact – c) After contact LO.2 Outline the basic properties of materials in an engineering context P2.1 Identify the key features and mechanisms of wear and corrosion Adhesive Wear ▪ If the driving force is sufficient to maintain motion: – The entangled particles deform. – If they are made of a brittle material, they can be torn off ▪ Therefore, it is can be prevented by: – Avoiding metal-to-metal contact – Increasing hardness – Increasing toughness to resist violent separation of metal particles – Increasing the surface finish to eliminate outgoing. LO.2 Outline the basic properties of materials in an engineering context P2.1 Identify the key features and mechanisms of wear and corrosion Adhesive Wear Video LO.2 Outline the basic properties of materials in an engineering context P2.1 Identify the key features and mechanisms of wear and corrosion Abrasive Wear ▪ Abrasive wear is the type of ▪ Abrasive wear a) to two bodies and b) to three wear mechanism that results in bodies the disintegration of the material on the surface due to the influence of the hard particle in contact with the surface. ▪ It also occurs when a hard surface or particles interacts or slides on the soft surface and causes material loss LO.2 Outline the basic properties of materials in an engineering context P2.1 Identify the key features and mechanisms of wear and corrosion Abrasive Wear Three-body abrasive wear ▪ In a body abrasion, the wear is caused by hard roughness belonging to one of the surfaces in contact, while in three body abrasion, the wear is caused by loose hard particles between the surfaces that are in relative movement. ▪ As an example of two-body abrasive wear, there is a drill penetrating a rock, while three-body wear can be cited by the jaws of a crusher breaking the rock, or by the presence of contaminating particles in an oil that It is used to lubricate the surfaces in sliding contact. Two body abrasive wear LO.2 Outline the basic properties of materials in an engineering context P2.1 Identify the key features and mechanisms of wear and corrosion Abrasive Wear Process ▪ a) and b) two body abrasion ▪ c) three body abrasive LO.2 Outline the basic properties of materials in an engineering context P2.1 Identify the key features and mechanisms of wear and corrosion Abrasive Wear Video LO.2 Outline the basic properties of materials in an engineering context P2.1 Identify the key features and mechanisms of wear and corrosion Fatigue Wear ▪ Fatigue wear is a type of wear in which the surface damage of the material takes place due to strain- induced on the surface for a particular number of cycles to a certain critical limit. ▪ Fatigue wear is caused by contact between asperities with very high local stress, and are repeated during sliding or rolling with or without lubrication. ▪ The result of fatigue wear is severe plastic deformation. Repeated, alternating mechanical stresses lead to the formation and propagation of cracks under the stressed surface, which is thus destroyed. LO.2 Outline the basic properties of materials in an engineering context P2.1 Identify the key features and mechanisms of wear and corrosion Fatigue Wear Schematic figure of fatigue wear mechanism in rolling contact for ▪ This type of wear occurs when parts are different materials subjected to high fluctuating stresses, which cause the appearance and propagation of cracks under their repetitive action. ▪ In the case of pieces subjected to sliding, the surface layers undergo intense deformations as a result of the simultaneous action of contact stresses and friction force. ▪ The stresses to which the materials are subjected, particularly in the superficial Schematic diagram wear particles causing the contact layers, promote, in most cases, alterations fatigue in the crystalline structure and in the grain size. LO.2 Outline the basic properties of materials in an engineering context P2.1 Identify the key features and mechanisms of wear and corrosion Fatigue Wear Video LO.2 Outline the basic properties of materials in an engineering context P2.1 Identify the key features and mechanisms of wear and corrosion Erosive Wear ▪ Erosive wear can be defined as degradation of material due to Schematic of Erosive Wear impact of particles travelling with significant velocity. ▪ Erosive wear or erosion takes place when a stream of particles or liquid droplets hits a surface. ▪ Normally a number of hits are required before any loss of material takes place. When particles hit the surface of brittle materials the loss takes place as brittle fracture. ▪ Loss of material on ductile materials takes place as a combination of chip formation, fatigue and shear failure. Erosion with water borne particles is called slurry erosion and is a common wear case in pumps, as well as cavitation erosion which is caused by imploding water vapor bubbles. LO.2 Outline the basic properties of materials in an engineering context P2.1 Identify the key features and mechanisms of wear and corrosion Erosive Wear ▪ Erosive wear is a phenomenon that affects a large number of machine elements hydraulic turbines, pumping as well as specific parts used in the oil industries. and petrochemical, among many other applications. ▪ With this type of wear, not only is there a loss of material and the Cavitation erosion. Low pressure forms cavities consequent failure of parts, but it is also associated with financial (bubbles) in the liquid. When the cavities implode close to a boundary, a double vortex is formed and the losses due to the time associated with repairing equipment and powerful jet between the two vortices damages the replacing worn components. material. ▪ The degree of wear is related to the angle of incidence of the particle with respect to the surface. ▪ Ductile materials appear to deform and possibly harden when struck perpendicularly, but at a critical angle of about 20°, the metal is removed by a shearing action. LO.2 Outline the basic properties of materials in an engineering context P2.1 Identify the key features and mechanisms of wear and corrosion Erosive Wear LO.2 Outline the basic properties of materials in an engineering context P2.1 Identify the key features and mechanisms of wear and corrosion Corrosion ▪ Deterioration suffered by materials by chemical and electrochemical interaction with the environment. ▪ Regressive metallurgy process (return to the original state that is of lower energy. It occurs in two stages: ▪ Metal oxidation ▪ Formation of microcell (anode, cathode and electrolyte) LO.2 Outline the basic properties of materials in an engineering context P2.1 Identify the key features and mechanisms of wear and corrosion Consequences of Corrosion ▪ Failures due to corrosion can lead to injuries and fatalities ▪ A BLEVE at an LPG Terminal near Mexico City resulted in 650 deaths and over 6,400 injuries. ▪ Damage to the plant was estimated at $ 31.3 million. BLEVE: Boiling liquid expanding vapor explosion LO.2 Outline the basic properties of materials in an engineering context P2.1 Identify the key features and mechanisms of wear and corrosion Consequences of Corrosion ▪ August 19, 2000, a 30-inch diameter “DRY” natural gas transmission pipeline operated by El Paso Natural Gas Company (EPNG) ruptured adjacent to the Pecos River near Carlsbad, New Mexico. ▪ The released gas ignited and burned for 55 minutes. ▪ Ten persons who were camping under a concrete-decked steel bridge that supported the pipeline across the river were killed and their three vehicles destroyed. LO.2 Outline the basic properties of materials in an engineering context P2.1 Identify the key features and mechanisms of wear and corrosion Consequences of Corrosion ▪ North Slope oil spill was caused by corrosion in the transit line, according BP PLC officials. ▪ The corrosion may have been due to the water and sediments that are carried with the viscous oil, said company spokesman Daren Beaudo.” ▪ – Associated Press 03/23/2006 ▪ It was later determined the main cause was Microbiologically Influenced Corrosion (MIC) LO.2 Outline the basic properties of materials in an engineering context P2.1 Identify the key features and mechanisms of wear and corrosion Consequences of Corrosion November 2008 - USA ▪ Another “Dry Gas Pipeline” ▪ No casualties were reported. LO.2 Outline the basic properties of materials in an engineering context P2.1 Identify the key features and mechanisms of wear and corrosion Principles of Corrosion MATERIALS SPONTANEOUS ENVIRONMENT DEGRADATION CHEMICAL ELECTROCHEMICAL MECHANICAL REACTIONS REACTIONS FACTORS CORROSION SPONTANEOUS DEGRADATION OF MATERIALS REACTING ELECTROCHEMICALLY WHEN EXPOSED TO DIFFERENT ENVIRONMENTS. DEGRADATION MAY BE ENHANCED BY MECHANICAL EFFECTS. LO.2 Outline the basic properties of materials in an engineering context P2.1 Identify the key features and mechanisms of wear and corrosion A System Under Corrosion Electrochemical reactions are the origin of Ionically conducting liquid in corrosion. Two or more of such reactions which reactions take place Motion of non charged occur on the metal surface species (chemical work). ELECTRODE ELECTROLYTE Electrically charged species (ions and electrons), interacting with water dipoles Aqueous Corrosion: Metallic phase: Metallic wastage occurs Material Cl-, CO2, Electrochemical by anodic dissolution H2S, O2… process LO.2 Outline the basic properties of materials in an engineering context P2.1 Identify the key features and mechanisms of wear and corrosion Thermodynamic of Corrosion System How to measure half-cell’s potentials? Standard Hydrogen Electrode, SHE - - Platinum Electrode Zn(s) Zn2+ (aq) + 2e- 2H+(aq.) + 2e- H2(g) LO.2 Outline the basic properties of materials in an engineering context P2.1 Identify the key features and mechanisms of wear and corrosion Corrosive Agents ▪ Water ▪ CO2 ▪ Moisture ▪ H2 S Corrosive Agents ▪ Soil ▪ Acids ▪ Oxygen ▪ Sulfur ▪ Sulfide ▪ Etc. They make the electrolyte more aggressive therefore increasing the e- e- corrosion severity. Recall Oxygen Reaction CATHODE ANODE e- e- H+ Fe2 Ho + Ho H2 H+ LO.2 Outline the basic properties of materials in an engineering context P2.1 Identify the key features and mechanisms of wear and corrosion Corrosion Classification Pitting Classification based on mechanism of attack common in oil UDC and gas production system Uniform Attack Crevice Microbiological Intergranular Localized CUI Stray Current ENVIRONMENT Galvanic Dealloying/selective leaching METAL Mechanically Assisted Erosion Corrosion Corrosion Corrosion Fatigue Environmentally Induced Stress corrosion cracking Cracking Hydrogen damage FILC Flow Induced Corrosion Cavitation Impingement LO.2 Outline the basic properties of materials in an engineering context P2.1 Identify the key features and mechanisms of wear and corrosion Atmospheric Corrosion ▪ Degradation of material exposed to contaminated wet air ▪ The rusting of iron and steel, and the formation of patina (tarnish) on cupper, are examples of atmospheric Very high corrosion corrosion Protected structure LO.2 Outline the basic properties of materials in an engineering context P2.1 Identify the key features and mechanisms of wear and corrosion Atmospheric Corrosion Mechanism Electrolyte Air Water drops Cl- Cl- Anodic reaction: (Cathode) (Anode) Fe Fe2+ + 2e- Iron Atmospheric corrosion of Cathodic reaction: Iron or alloy steel O2 + 2H2O + 4e- 4OH- LO.2 Outline the basic properties of materials in an engineering context P2.1 Identify the key features and mechanisms of wear and corrosion Atmospheric Corrosion Primer parameters ▪ SO2 → SO3 ▪ Time of wetness* ▪ SO3 + H2O → H2SO4 ▪ Relative humidity ▪ NaCl, MgCl (> 60 - 70 %) ▪ H2 S ▪ Temperature ▪ NH3 ▪ Wind velocity and ▪ H2 O direction ▪ Shape ▪ Roughness * Hours per year when relative humidity, RH > 80 % and t > 0 oC LO.2 Outline the basic properties of materials in an engineering context P2.1 Identify the key features and mechanisms of wear and corrosion Atmospheric Corrosion LO.2 Outline the basic properties of materials in an engineering context P2.1 Identify the key features and mechanisms of wear and corrosion Atmospheric Corrosion LO.2 Outline the basic properties of materials in an engineering context P2.1 Identify the key features and mechanisms of wear and corrosion Atmospheric Corrosion Corrosion Control LO.2 Outline the basic properties of materials in an engineering context P2.1 Identify the key features and mechanisms of wear and corrosion General Corrosion The following is an example of uniform corrosion caused by CO2. ▪ Occurs uniformly over large area of the metal ▪ Metal loss the same along large area ▪ Uniform thinning measured in mm/year or mpy (mils per year). ▪ Type of attack by O2, CO2, H2S ETOTAL = E Mechanical design + D thinning due to corrosion LO.2 Outline the basic properties of materials in an engineering context P2.1 Identify the key features and mechanisms of wear and corrosion Pitting Corrosion Pitting is one of the most common types of Pitting corrosion on localized corrosion aluminum The attack starts at discontinuities in micro or sub-microscopic passivation films, in specific environments. Example: stainless steels in environment containing chloride ions. Common electrochemical reaction occurring during O2 pitting corrosion of iron H2O H2O + O2 + 4e- → 4OH- Cl- Passive film (nm) Fe→ Fe2+ + 2e- Stainless Steel NaCl → Na+ + Cl- LO.2 Outline the basic properties of materials in an engineering context P2.1 Identify the key features and mechanisms of wear and corrosion Pitting Corrosion - Mechanism ▪ Dissolution and repassivation processes compete in places where the film breaks, until pitting starts. Ion migration and electrochemical reaction at the pit Fe2+, OH-, Cl- Fe2+ + 2OH- → Fe(OH)2 insoluble O2 Mechanism H2O Fe2+ + 3Cl- → FeCl3+ e- Cl- soluble Passive film (nm) FeCl3+ 2H2O + e-→ Fe(OH)2 + 2H+ + 3Cl- Metal Stainless Steel Cl- migration to active localized spots Acidizing medium LO.2 Outline the basic properties of materials in an engineering context P2.1 Identify the key features and mechanisms of wear and corrosion Pitting Corrosion - Mechanism Propagation stage FeCl3+ 2H2O + e -→ Fe(OH)2 + 2H+ + 3Cl- Acidification inside pit Na+ Na+ Na+ Na+ Ion migration to the O2 O2 O2 O2 pit Cl- Cl- Cl- OH- OH- OH- OH- Passive film (µm) Fe2+ Cl- e- Fe2+ H+ Cl- H + Fe2+ e- e- Fe2+ Cl- e- Fe2+ Stainless Steel 2H2O + O2 + 4e- → 4OH- Fe→ Fe2+ + 2e- LO.2 Outline the basic properties of materials in an engineering context P2.1 Identify the key features and mechanisms of wear and corrosion Crevice Corrosion Mechanism ▪ It occurs in narrow openings (gaps) or confined spaces in which the electrolyte has not free access ▪ Example: Under gasket and deposits; undercuts, incomplete joints O2 + 2H2O + 4e- → 4OH- (Basic solution) Fe → Fe2+ + 2e- Oxygen differential Cell ▪ After some time oxygen is consumed in the confined space LO.2 Outline the basic properties of materials in an engineering context P2.1 Identify the key features and mechanisms of wear and corrosion Crevice Corrosion Propagation Oxygen Final Stage of Crevice Corrosion Differential Cell O2 O2 OH- e- Water OH- e- e- Water e- e- Metal Na+ O O2 Metal Na+ 2 O2 OH- Fe OH- e- 2 O2 Fe2 Fe2 Fe2 Fe 2 O2 Fe2 Fe2 Na+ O2 O+ O C+l- O+ 2 2H + Fe+2 H+ +H+ Na+ Fe2 2 2 H++ Cl +- O2 O2 O2 Cl - + O2 + O2 Fe2 O2 + Fe2 + Fe - H + Cl- H+ H+ Cl- Cl O2 +Cl- H H + Cl OH OH - - Cl - + Fe2 2 Fe Fe2 - OH- OH- Fe2 OH- Fe2 Fe2 Fe2 Fe2 + + + e-+ + + + Metal + e- e- Metal e- e- e- LO.2 Outline the basic properties of materials in an engineering context P2.1 Identify the key features and mechanisms of wear and corrosion Crevice Corrosion - Prevention ▪ Using welded joints instead of riveted. ▪ Specify full penetration weld joints and avoid dots. ▪ Use non-absorbent gasket (i.e. Teflon, metal). ▪ Avoid stagnation of the fluid and solids accumulation. ▪ Install drainage in vessels. LO.2 Outline the basic properties of materials in an engineering context P2.1 Identify the key features and mechanisms of wear and corrosion Microbiologically Influenced Corrosion - MIC ▪ Is a form of localized corrosion that can produce accelerated metal loss from a small area due to the accumulation of biomass and the metabolic process of sessile bacteria. ▪ Types of Bacteria: SRB, APB, Methanogens- MIC – Carbon Steel Pipeline Archea, Iron-oxidizing, etc. Planktonic Sessile Biomass Sessile http://cfm.mines.edu/images/research1_fig1.jpg ed LO.2 Outline the basic properties of materials in an engineering context P2.1 Identify the key features and mechanisms of wear and corrosion Microbiologically Influenced Corrosion - MIC ▪ Common bacteria associated with MIC – Sulfate Reducing Bacteria (SRB) – Anaerobic – Acid Producing Bacteria (APB) – Aerobic/Anaerobic – Slime Forming Bacteria - Aerobic ▪ There are a wide variety of environment including soil, water, crude oil, petroleum products, drilling fluids, where bacteria can develop ▪ Can grow in: – pH: 0 to 11 – T: 0 to 235 °F – High Salinity LO.2 Outline the basic properties of materials in an engineering context P2.1 Identify the key features and mechanisms of wear and corrosion Microbiologically Influenced Corrosion - MIC ▪ Is a form of localized corrosion that can produce accelerated metal loss from a small area due to the accumulation of biomass and the metabolic process of sessile bacteria. MIC – Carbon Steel Pipeline ▪ Types of Bacteria: SRB, APB, Methanogens- Archea, Iron-oxidizing, etc. ▪ SRB – organism that metabolically reduces sulfate into H2S. – Most trouble-producing organism – One of its species known as Desulfovibrio APB: Acid Producing Bacteria – Doesn't seem to affect titanium. LO.2 Outline the basic properties of materials in an engineering context P2.1 Identify the key features and mechanisms of wear and corrosion Microbiologically Influenced Corrosion - MIC Impact ▪ Aggressive corrosion resulting in pitting and cracking. ▪ SRB may cause hydrogen induced cracking to hard materials. ▪ Corrosion rate of steel in SRB bearing environment is six times higher than in the medium w/o SRB. ▪ SRB.-Self –Aligning Rod End Bearing MIC Mechanism ▪ Microorganisms excrete waste products – metabolites. ▪ Polymeric metabolites form the biofilm matrix ▪ At fluid/metal interface, biofilm-free areas are different from biofilm- covered areas. This results in an electropotential gradient at the metal surface – Anode–Cathode reaction ▪ Many metabolites are weak organic acids. Inorganic salts, such as NaCl, react with these weak acids, forming strong inorganic acids (e.g. HCl) Anaerobic Bacteria Mechanism: SRB ANODE: Fe → Fe2+ + 2e- H2O → H+ + OH- Metabolic CATHODE: H+ + e- → H (Adsorbed) activity of SO42- + 8H(Adsorbed) + e- → S2- + 4H 2O bacteria 4Fe + SO42- + 4H2O → FeS + 3Fe(OH)2 + 2OH - Bacteria Video Anaerobic Bacteria Mechanism: SRB ▪ Bacteria feed from: – Carbon, nitrogen and phosphorous – Dissolved iron: they need high concentrations. – Ions of sulfate or sulfite. Anaerobic Bacteria Mechanism ▪ The attack is located in hemispherical depressions. ▪ In low-speed fluid there are corrosion products on attacked area. ▪ If the attacked area is acidified in a short time, H2S can be detected. ▪ H2S + Steel surface ➔Iron sulfide, pitting corrosion ▪ Hydrocarbons transported at very slow velocity promote deposit formation inside pipelines. This increase corrosion Aerobic Bacteria Mechanism ▪ In the presence of oxygen, sulfur oxidizing bacteria produces H2SO4, at concentrations that can reach up to 10% 2S + 3O2 + 2H2O → 2H2SO4 ▪ The attack is located in hemispherical depressions. The H2SO4 strongly attack ▪ In low-velocity fluid the steel corrosion products are found on the attacked area Bacteria Video Microbiological Corrosion - Prevention Aerobic bacteria are found in: Oil fields: oil wells, pipes, tanks, among other ▪ To prevent the attack: ▪ Use of biocides (Cl2 or sodium hypochlorite, in water cooling). Glutaraldehyde, tetrakis- hydroxymethyl-phosphonium (THPS),. ▪ Dosage ammonium salts. ▪ Use paints containing copper compounds. ▪ Keep surfaces clean – cleaning tools. MIC Cases: MIC of Pump Housing of an ESP ▪ Problem ▪ Numerous pitting on ID – Large thru wall pits and severe corrosion at the ▪ Thru wall pitting ID to ID surface of housing of ESP (artificial lift) OD ▪ Environment – Producing fluid ▪ Total service hrs. – 200 days (Target service life 365 days) ▪ Material – Mild steel with Monel coating on OD surface ▪ Temperature – 126°F MIC Cases: MIC of Pump Housing of an ESP ▪ SEM image of cross section of MIC pits ▪ High content of S in corrosion products Under Deposit Corrosion - UDC ▪ Is a form of localized corrosion that can produce accelerated metal loss from a small area due to the accumulation of deposits ▪ The environment is different than its surrounding creating a concentration cell and thus a galvanic effect and high local corrosion rates. http://www.martinpipeinspection.com/i/MIC_pipe_corr osion.png ▪ This can happen on external or internal metal surfaces ▪ Related with MIC. Bacteria when attached to the surface of metals produces biomass and in addition to their metabolic processes that produce MIC. ▪ On a pipelines, internally, is typically found near the 6:00 o’clock position. http://clients.eceglobal.com/pictures/Insp o -&- Approvals/Under_Deposit_Corroded_Pipe.gif ▪ Found on the internal or external Under Deposit Corrosion – UDC - Prevention ▪ Keep surfaces clean – cleaning tools. ▪ Corrosion Inhibitors ▪ Scale Inhibitors Intergranular Corrosion ▪ Is a form of localized corrosion that occurs between the grain boundaries of the metals due to impurities or damage cause by an inadequate welding process. Corrosion Under Insulation - CUI ▪ Is a form of localized corrosion that can produce accelerated metal loss from specifics areas underneath insulation jackets. ▪ These areas become susceptible to corrosion due to: – Leakage of water from the environment where the protective metal jacket is damaged, the metal jacket joints. – Where the metal jacket has not been sealed correctly against the equipment. – Due to water condensation from temperature drops of the pipe process. ▪ Insulation is used on pipelines where it is required to maintain the temperature inside the pipeline. ▪ Once moisture ingress inside the insulation material it acts as an sponge maintaining the humidity and due to the temperature of the pipe, usually high temperatures, the corrosion rates are high inducing premature failures. Corrosion Under Insulation – CUI Corrosion Under Insulation – CUI - Prevention ▪ Use of Coatings Prior to insulating the pipelines ▪ Protect the metal jacket to avoid water ingress ▪ Repair metal jackets ▪ Avoid walking on top of the insulation jackets ▪ Properly seal the joints between the protective jacket and the pipeline. Galvanic Corrosion It occurs when metals far away in the galvanic series, are in electrical contact. Both materials immersed in same electrolyte Electrolyte Zn2 Cu2 A potential difference set up between + I + both material establishing a current flow thought the coupled metals Zn e C - u Support reduction reactions on its surface Cathode Anode Dissolve Galvanic Corrosion Galvanic series of some metals and alloys in sea water Platinum Gold Graphite Titanium Silver Chlorimet 3 (62 Ni, 18 Cr, 18 Mo) Noble or cathodic Hastelloy C (62 Ni, 17 Cr, 18 Mo) The driving force 18 - 8 Mo stainless steel (passive) 18 - 8 stainless steel (passive) Chromium stainless steel 1–1 – 30 % Cr (passive) of Galvanic Inconel (80 Ni, 13 Cr, 7 Fe) (passive) Nickel (passive) Corrosion Silver solder Monel (70 Ni, 30 Cu) Cupronickels (60 - 90 Cu, 40 - 10 Ni) Bronzes (Cu - Sn) Copper Brasses (Cu – Zn) Chlorimet 2 (66 Ni, 32 Mo, 1 Fe) Hastelloy B (60 Ni, 30 Mo, 6 Fe, 1 Mn) Inconel (active) Níckel (active) Tin Potential Lead Lead-tin solders 18 - 8 Mo stainless steel (active) Difference 18 - 8 stainless steel (active) Ni-Resist (High Ni cast iron) Chromium stainless steel,13 % Cr (active) Cast iron Steel or iron 2024 aluminum (4.5 Cu, 1.5 Mg, 0.6 Mn) Aluminum Active or anodic Cadmium Commercially pure aluminum (1100) Galvanized steel Zinc Magnesium and magnesium alloys Galvanic Corrosion Essential Factors Affecting Galvanic Corrosion Potential difference Geometry Electrolyte and Galvanic distance Carbon corrosion Steel Material Area Ratio Stainless polarization Steel Galvanic Corrosion ELECTROLYTE ANODE CATHODE Unfavorable ratio Area ratio = High Corrosion ELECTROLYTE rate CATHODE ANODE Favorable ratio Low Corrosion rate Galvanic Corrosion-Prevention Avoid combination of metals or alloys, widely separated in the galvanic series ▪ Material selection Deaeration of water, ▪ Environment Control corrosion inhibitor ▪ Barrier coating Coating to Isolate the metals from the environment ▪ Electrical isolation ▪ Cathodic protection Joins between dissimilar metals ▪ Design can be isolated to interrupt the electrical continuity (i.e. nonmetallic inserts, washers, Area of active material > area of fittings and coatings noble material Unfavorable area ration should be avoided Stray-Current Corrosion Surface installations Cathodic protection system Stray-current corrosion Stray-Current Corrosion Power The affected pipeline is Supply electrically connected Tank to the protected bottom tank Anode Cathode Anode Steel Pipe Stray-Current Corrosion Stray-current corrosion of a buried Stray-current pipeline, cause by electric railways corrosion Trolley electrical wire Trolley G Track Pipeline Soil Current flow through the soil and Current leaves the pipeline and enters the pipeline returns to the soil Stray-Current Corrosion Stray-current corrosion - Control Trolley electrical Trolley wire G Bonding the Track rail and the pipe Pipeline Soil Current flow through the soil Current leaves the pipeline and returns to the soil Reducing and enters the pipeline stray-current corrosion Stray-Current Corrosion Effect of current flowing along a buried pipeline on corrosion near a coupling Soil Current flow Current flow High resistance gasket The insulating gasket prevents the current to flown through the pipe. If the voltage is Stray-current corrosion too high, it may induce the current enter the soil Mechanical Degradation Interaction between the surface and solid Hard particles moving along particles contained in a fluid (or a a surface multicomponent fluid) ABRASION EROSION WEAR Removal of surface material Mechanical Degradation ▪ Erosion-corrosion ▪ Fretting corrosion ▪ Corrosion - Fatigue Erosion-Corrosion Fretting Fatigue corrosion Overload fracture fracture Mechanical Degradation Cyclic loading In the presence of a corrosive environment Cracking Fatigue Corrosion Surface in Load movement Components exposed to corrosive environment Fretting corrosion Fatigue Fatigue Corrosion Tendency of metal to fracture under repeated cyclic stressing Reduction of fatigue resistance due to the presence of a corrosive medium causing pitting Stress Fatigue corrosion fracture Schematic illustration of fatigue behavior of ferrous and nonferrous Overload fracture alloys1 1 Corrosion Engineer, M. Fontana and R. Greene, McGraw Hill Book Co., N.Y. Fatigue Corrosion Morphology features ▪ Cracks initiate from the surface in notches, sharp edges or pits ▪ Fracture is usually Low magnification optical transgranular photomicrograph of an axial cross- ▪ Fracture surface shows a section reveals circumferential grained zone together with a corrosion fatigue cracks. The cracks are also straight and transgranular, fibrous zone due to characteristics of fatigue cracking. mechanical overload (Mag. 100X, oxalic etch) Erosion Corrosion-Prevention ▪ Suitable selection of materials: high superficial hardness and a good corrosion resistance ▪ Appropriate design: avoiding obstruction that generate turbulence. Use of large angle elbows. ▪ Change of environment: filtration or precipitation of solids, precipitation of water droplets ▪ Use of corrosion-resistant coating: metallic, ceramic or polymer coating Fatigue Corrosion-Prevention ▪ Reduction of stress level by adjusting design. e.g. avoid notches or sharp edges. ▪ Compression stresses induce on the surface. ▪ Apply thermal treatment to reduce residual stresses. ▪ Use of coatings. ▪ Use of corrosion inhibitors. Flow Assisted Corrosion Cavitation Bubbles formed in the Flow Induced Corrosion fluid impact the surface High velocity fluid and explode. impacting the surface Removal of scale Flow or protective films Shallow pits Pitting Corrosion Cavitation corrosion Impingement corrosion enhancement Impingement corrosion Flow Wall thickness reduction Impingement Corrosion In the oil and gas industry, all type of equipments, expose to fluid in motion, are susceptible to erosion-corrosion phenomena Erosion-corrosion Liquid droplets traveling at high velocity Wall thickness in the hydrocarbon stream, dissolve reduction protective scales (e.g: oxides, sulfides) Flow Very reactive surfaces are formed and exposed to aggressive environment Corrosion is enhanced Impingement corrosion in an elbow of a wet gas pipeline Impingement Corrosion Wall Thickness Reduction Original Thickness Cavitation Cavitation-corrosion in a pump - Corrosion impeller Pressures changes in a fluid Bubbles contained in the fluid implode Scales or protection corrosion product (e.g. passive oxide film on stainless steel) are removed Fresh surface is exposed to the aggressive Shallow pits Corrosion is environment Cavitation accelerated corrosion Cavitation - Corrosion Cavitation corrosion in a carbon steel spring in contact ▪ Bubbles formed inside a liquid phase collapse destroying protective scales or with oil-water emulsion passive film ▪ Stresses produced by bubbles collapsing may be as high as 60 ksi Shallow pits Cavitation corrosion Stress-Corrosion Cracking (SCC) Stress-Corrosion Cracking (SCC) Material susceptibility Tensile SCC Environment stresses Hydrogen damage SSC HIC SOHIC Stress-Corrosion Cracking (SCC) Synergistic effect Stress-Corrosion Cracking (SCC) Material susceptibility Tensile SCC stresses Environment SCC in AISI 316 stainless steel pipe Stress corrosion cracking (SCC) is transporting chloride contaminated water caused by the combined action of a static tensile stress and corrosion on a susceptible material Stress Corrosion Cracking Mechanism Overview Stress-corrosion cracking is a delayed failure process, taking place in three stages Stage 1 Crack initiation and propagation It initiates and propagates at slow rate Stage 2 or steady-state crack propagation 10-9 – 10-6 m/s Stage 3 crack propagation or final failure Some Morphology Features of SCC Transgranular SCC Intergranular Schematic SCC representation of SSC morphology a SCC in a carbon steel pipeline Stress Corrosion Cracking - Prevention ▪ Avoid use of susceptible alloy in specific environment. e.g. Austenitic stainless steel in Cl- containing medium. ▪ Reduce mechanical stresses by design (pipe flexibility) ▪ Apply thermal treatment to reduce residual stresses. ▪ Control of aggressive species concentration to values below ppm. Control of pH and fluid temperature. ▪ Use corrosion inhibitors. Hydrogen Damage ▪ Damage due combined SSC action of Hydrogen and applied tensile or residual HIC stresses. SOHIC ▪ Hydrogen interacts with microstructural defects. ▪ It manifests itself as cracking, blistering, hydride formation and loss in tensile ductility. Hydrogen Damage Sulfide Stress Cracking, SSC Environment: Hydrogen sulfide containing aqueous medium Alloys with mechanical resistance > 100 ksi (yield strength), under tensile stress may be affected -100 to 100 oC (115 -220 oF) Temperature More severe around 20 oC (70oF) FORMS OF Hydrogen damage CORROSION SSC, Sulfide Stress Cracking Environment: Hydrogen sulfide containing aqueous medium High mechanical resistance alloy for deep well completion: e.g. API P110 SSC susceptible materials in oil and gas production systems Welding hardness 22 HRC SSC: Prevention NACE MR0175/ISO15156 Sulfide Stress Cracking Resistance Metallic Materials for Oilfield Equipments PH2S = 0.05 psia SCC susceptibility regions defines by Total pressure (psia) SSC region system total pressure and H2S partial 65 psi total pressure No SSC region pressure % H2S SSC: Prevention NACE MR0175/ISO15156 Sulfide Stress Cracking Resistance Metallic Materials for Oilfield Equipments Environment susceptible to SSC: ▪ PH2S > 0,05 psia Material ▪ PT > 65 psia hardness specification HRC < 22 Hydrogen Induced Cracking, HIC Morphology: Planar cracks relating to blistering 2H+ + 2e- H2 Material: Yield strength < 80 ksi X Hardness 22 HRC H H 1 2 stress FeS H H H2 H H2 2 Steel Environment: Wet H2S, PH2S 0.015 psi Hydrogen Induced cracks pH: acid Temperature: 50 – 95 oC Stress Orientated Hydrogen Induced Cracking, SOHIC Mechanism Stress assisted propagation of blisters or internal fissures caused by Hydrogen Propagation takes place through stress the material thickness Cracks propagate in a step pattern Stepwise cracking HIC Prevention ▪ Clean materials must be used (very low P y S HIC resistant material: content). globular ferrite-perlite ▪ Quantity and morphology inclusion control is required microstructure (rounded inclusion). ▪ Refined metal grain. ▪ Using Corrosion inhibitors Traditional material with A B an elongated ferrite-perlite microstructure. API 5LX steel pipeline CO2 and H2S Corrosion CO2 and H2S Corrosion ved CO2 Corrosion CO2 and H2S Corrosion: Rule of Thumb CO2 partial pressure, Relative corrosion psia intensity < 7 Negligible 7 - 17 Negligible to light 17 - 30 Moderate > 30 Severe Corrosion Severity criteria based on CO2 partial pressure. These are only guidelines based on experiences… CO2 and H2S Corrosion Some guidelines relate to H2S corrosion Between 20 – 60 oC, corrosion is inhibited by FeS scale forming on surface metal H2S at levels below the NACE criteria for SSC (MR0175/ISO 15156, NACE) reduces general metal loss rates but can promote pitting. H2S corrosion in a sour gas flowline PCO2/PH2S > 500 CO2 Corrosion PCO2/PH2S ration to determine which corrosion predominates PCO2/PH2S < 200 H2S Corrosion Corrosion Inhibitor Guideline CORROSION CONTROL STRATEGIC PLANNING Integrity Production Cost SHE Impact* SELECTION OF CONTROL METHODS * SHE: Safety, Hygiene and Environment Internal External Chemical Treatment Anodic Sweetening Protection Dehydration Coatings Cathodic Corrosion Inhibitors Protection Neutralizing ▪ Metallic Biocides ▪ Non-Metallic Scavengers Corrosion Inhibitor Selection DESIGN OPERATION AND MAINTENANCE INHIBITOR SELECTION Metal to protected, EVALUATION Temperature, Concentration, Persistence, Partition INJECTION SITES between phases, compatibility, SHE PREDICTION INHIBITION SYSTEM ▪ CORROSION ALLOWANCE ▪ TIME TO FAILURE MONITORING AND INSPECTION PROGRAM RELIABILITY AND MONITORING PERFORMANCE SYSTEM Corrosion Inhibitor Selection Corrosion Inhibitor Selection Environment Composition Corrosion inhibitors Concentration Corrosion inhibitors have a critical concentration to be effectives Insufficient Optimun Excesive Vcorr Blank (without corrosion inhibitor) Represet major Corrosion Effective unnecessary cost inhibitor in Corrosion is Inhibitor possible, excess may increase corrosion Inhibitor Concentration Corrosion Corrosion Inhibitor Inhibitor Selection Selection Fluids Corrosion Organic Compounds inhibitors are Low molecular weight adsorbed from the Gas phase gas phase onto High vapor pressure the metal surface Interface Inhibitor Organic Compounds Corrosion inhibitors are adsorbed from Dispersable or water Liquid phase the water and oil soluble phase onto the metal surface Dispersable or Oil Soluble Corrosion Corrosion Inhibitor Inhibitor Selection Selection Fluids Flowline Controling internal Organic Corrosion corrosion Inhibitor Pipeline Water in contact Water High Water Cut Continuos injection with metal soluble Both phases are Water and Oil Continuos injection Water and present: oil and or emulsion in Oil water contact with metal Batch Treatment dispersable Turbulent and high Oil in contact with Continuos injection Oil soluble velocity flow metal Corrosion Inhibitor Selection Corrosion Inhibitor Selection Flow Pattern Fluid velocity limit up to 10 m/s is recommended for using corrosion inhibitor Pattern Corrosion inhibitor recomended Multiphase flow patterns in horizontal pipe If vapor phase is Vapor phase Shear stress higher Dispersed bubble increased Oil Soluble high velocity flow Mist Vapor phase If vapor phase is higher Slug Oil and water Phases are mixed Elongated bubble dispersible Annular Oil and water Phases are mixed Shear stress dispersible increased Stratified Wavy If water phase is C. Palacios. Corrosion. NACE. 1992 Stratified Water soluble higher Level 1: Basic Maintenance Practices External Corrosion Pipeline External Type of External Corrosion on Pipeline Corrosion ▪ General ▪ Atmospheric ▪ Galvanic ▪ Stray-current ▪ Localized ▪ Pitting ▪ Crevice ▪ Microbiologically corrosion ▪ Environmentally Induced ▪ Stress Corrosion Cracking ▪ Hydrogen damage Pipeline External Corrosion Why external corrosion occurs on protected pipelines ▪ Disbonded coatings ▪ Holydays and coating damage ▪ AC and DC Stray Current Interference ▪ Shielding from other materials ▪ Inadequate cathodic protection Pipeline External Coating ▪ Typically several different types of coatings are used in a pipeline project (where different coating Parameters are needed). ▪ Different sections of a pipeline : ▪ Mainline coating ▪ Bends and fittings ▪ Field Joint coating ▪ Coating repairs on site ▪ This creates issues of compatibility , Coating Standardization and increased coating costs Pipeline Bitumen (Bit) External Coatings Onshore Increasing Technology - Operating Temperature Coal-Tar Enamel (CTE) Onshore Asphalt enamel (AE) Onshore Cold-Applied Tapes (CAT) Onshore 2Layer Polyethylene (2LPE) Onshore / Offshore Fusion Bonded Epoxy (FBE) m Onshore / Offshore 3-Layer Polyethylene (3LPE) Onshore / Offshore 3 Layer Polypropylene (3LPP) Onshore /Offshore Offshore Negative Buoyancy (Concrete Weight Coated) Offshore Others Insulated Pipe (PU foamed pipe Jacketed) Onshore / Offshore Deep Water Solutions (Thermotite) Offshore Pipeline External Coating High Temperature Coatings Coating Type Maximum Operating Temperature† Fusion Bonded Epoxy (FBE) 75ºC (dry condition) 2-Layer Polyethylene (2LPE) 60ºC 3-Layer Polyethylene (3LPE) 85 - 90ºC 3-Layer Polypropylene (3LPP) 110 - 140ºC Composite Coatings (HPCC) 85ºC † - Data gathered from pipe coating companies' published literature. Special grades of raw materials may be rated higher. External Corrosion Considerations External Corrosion Coating Performance Requirements ▪ Low permeability ▪ Adhesion ▪ Impact and abrasion resistance ▪ Flexible ▪ Inert ▪ Application and repair ▪ Temperature and UV stability ▪ Resistant to cathodic disbondment Protective Coating – Inspection ▪ Surface preparation ▪ Cleanliness ▪ Anchor profile ▪ During application ▪ Verify conditions ▪ Application technique ▪ Wet film thickness ▪ Post application ▪ Dry film thickness ▪ Adhesion ▪ Holidays Diagram for fusion bonded epoxy application Qualification requirements for FBE coatings Test Acceptance Criteria Cathodic Disbondment Maximum average radius: (24 hours) 6.0-mm (0.25 inches) Cathodic Disbondment Maximum average radius: (28 days) 8.0-mm (0.3 inches) Cross-Section Porosity Rating of 1 to 4 Interface Porosity Rating of 1 to 4 Flexibility (3o/Pipe No cracks, tears, or Diameter at 0 o C[32 o F] delamination or -30 o C [122 o F]) Impact Resistance 1.5 J (13 inch-pounds) minimum Hot-Water Soak Rating of 1 to 3 Diagram for PP three layers application External Corrosion - Field joint systems Matching system FBE 3-layer PE/PP Complementary system Cold applied tape Heat shrink sleeve External Corrosion Considerations Cathodic Protection Cathodic Protection Cathodic Protection Cathodic Protection Protection Criteria Potential of pipeline ≤ -850 mv vs. Cu/CuSO4 reference electrode (under aerobic condition). Potential of the pipeline ≤ -850 mv vs. Cu/CuSO4 reference electrode (under anaerobic condition where microbial corrosion ma be a factor Negative potential shift of 300 mV when current is applied Positive potential shift of 100 mV when the current is interrupted Cathodic Protection Relation between potential and corrosion Risk for buried pipeline Potential (V vs. Cu/CuSO4) Condition of Steel -0.5 to -0.6 Intense Corrosion -0.6 to -0.7 Corrosion -0.7 to -0.8 Some Protection -0.8 to -0.9 Cathodic Protection -0.9 to -1.0 Some Overprotection -1.0 to -1.1 Increased Overprotection -1.1 to -1.4 Increasingly severe overprotection, coating disbondement and blisters, increasing risk of hydrogen embritlement Cathodic Protection ELECTRODE READ Reference Cu-SO4Cu Copper –copper sulfate (Cu/SO4Cu) -0,850 V Electrode Type Ag-AgCl Silver-Silver Chloride (Ag/AgCl) -0,800 V Calomel Hydrogen or Calomel (H+/H2) -0,77 V Zn Zinc (Zn/Zn++) +0,25 V Cathodic Protection Sacrificial Anode CP System Design The simplest cathodic protection system is the galvanic anode system. In this type of system, a mass of metal is electrically connected to the structure being protected. ▪ Sacrificial Anodes ▪ Aluminum - primarily used in seawater. ▪ Magnesium - used in soil and fresh water. ▪ Zinc ▪ One alloy for seawater ▪ One alloy for soil and fresh water. ▪ Three criteria to be satisfied: ▪ Initial polarization ▪ Mean - mass of material over lifetime ▪ Final current demand Cathodic Protection Sacrificial Anode CP System Design Disadvantages Advantages ▪ No external power required ▪ Limited current capacity and power output ▪ Ease of installation (and relatively low installation ▪ High resistivity environment or large structure costs) requires excessive number of electrodes. ▪ Unlikely cathodic interference in other structures Maximum resistivity of 6000 to 10000 Ώ.cm is generally regarded as the limit, depending of the ▪ Low-maintenance system (assuming low current coating quality demand) ▪ Shorter anode life ▪ System is essentially self-regulating ▪ No visual indication that it is operating properly ▪ Relatively low risk of overprotection ▪ Relatively uniform potential distribution Cathodic Protection Cathodic protection design parameters and coatings design considerations Design parameter Typical Value Seawater Resistivity 20 – 25 ohm-cm Saline Mud 100 – 150 ohm-cm Anode open circuit potential - -1.05 V (Ag/AgCl) buried Anode open circuit potential - -0.95 V (Ag/AgCl) seawater Anode Consumption 1280 A hours/ pound Anode Utilization Factor 0.80 Coating Breakdown Factor (FBE) 0.5% to 1.0% (initial) 10% (after 30 years) Insulation Breakdown Factor 0.5% to 1.0% (initial)
