science engineering Flashcards
5 steps in material selection
- Identify condition of exposure ICE
- Establish strategy ofevaluating candidate materials
- Identify candidate materials
- Evaluating materials ofconstruction
- Selecting the final materialswith necessary documentation
What are 3 Chemical Engineering Design Works?
- Modification and additions to existing plants. usually carried out by the plant design group.
- New production capacity to meet growing sales demand, and the sale of established processes by contractors. Repetition of existing designs, with only minor design changes.
- New processes, developed from laboratory research, through pilot plant, to a commercial process. Even here, most of the unit operations and process equipment will use established designs.
What are the 3 Design Documents?
- Calculation sheets.
- Drawings.
- Specification sheets.
What are 3 Structural Corrosions?
- Graphitic corrosion
- Parting or de-alloying corrosion
- Dezincification or biological corrosion
What are the 5 Standards for Materials?
- AISI (American Iron & Steel Institutes)
- SAE (Society of Automotive Engineers)
- ANSI (American National Standard Institutes)
- ASME (American Society of Mechanical Engineers)
- ASTM (American Society for Testing Material) or ISO (International Organization for Standardization)
- ISO (International Organization for Standardization)
What are the 3 types of Stainless Steel?
- Ferritic 13-20% Cr, <0.1%C, with no nickel
- Austenitic 18-20% Cr, >7% Ni.
- Martensitic 12-14% Cr, 0.2 to 0.4%C, up to 2% Ni.
6 Contents of Specification Sheet
- Identification
- Function
- Operation
- Materials handled
- Basic design data
- Essential controls
- Insulation requirements
- Allowable tolerances
- Special information
Modern Steps in Design
- Determine Customer Needs
- Set Design Specifications
- Generate Design Concepts
- Build Performance Models
- Predict Fitness of Service
- R&D if Needed
- Customer Approval
- Economic Evaluation,Optimization and Select Design
- Design Specification andEquipment Selection
- Procurement and Construction
- Begin Operation
General Classification of Equipment
- Columns (Separation/Purification equipment)
- Vessels (Handling/Preparation/Storage Equipment/Separation/Purification)
- Reactors (Reaction Equipment)
- Heat Exchangers and Furnaces (Heat Transfer Equipment)
- Pumps, compressors, and transport equipment
- Instrument (Process Control Equipment)
- Special Equipment(Purification, separation)
an acceleration in the rate of corrosion attack in metal due to therelative motion of a corrosive fluid & metalsurface
Erosion
minimized by using harder materials, minimizing friction (via lubrication), or designing equipment so that no relative movement of parts takes place
Fretting Corrosion
localized form of corrosion usually associated with a stagnant solution on the micro- environmental level
Crevice
aka ‘dissimilar metal corrosion’ or wrongly ‘electrolysis’; corrosion damage induced when 2 dissimilar materials are coupled in a corrosive electrolyte
Galvanic Corrosion
aka selective leaching (selective removal of 1 element from an alloy by corrosion processes); in a gray cast iron, a brittle graphite skeleton remains following preferential iron dissolution
Dealloying/Graphitic Corrosion
there are several categories of hydrogen phenomena that are localized in nature; atomic hydrogen (not the molecule) is the smallest atom & is small enough to readily diffuse through a metallic structure; when the crystal lattice is in contact or saturated w/ atomic hydrogen, the mechanical properties of many metals & allows are diminished
Hydrogen Cracking
associated w/ a flow-induced mechanical removal of the protective surface film that results in a subsequent corrosion rate increase via ether electrochemical or chemical processes; mechanical destruction of a metal by abrasion or attrition caused by the flow of liquid or gas (w/ or w/o suspended solids)
Erosion-Corrosion
occurs when a fluid’soperational pressure drops below its vapor pressurecausing gaspockets & bubbles to form& collapse w/c can occurin a rather explosive & dramatic fashion
Cavitation
‘localized corrosion causedby turbulent flow’;entrained air bubblestend to accelerate this action, as do suspended solids; occurs in pumps, valves,orifices, on heat-exchanger tubes, & at elbows & tees in pipelines
Impingement
result of the combined action of an alternating or cycling stresses& a corrosive environment; this thought to cause ruptureof the protective passive film upon w/c corrosion is accelerated
Corrosion-Fatigue
corrosion damage at the asperities of contact surfaces; this damage is induced under load & in the presence of repeated relative surface motion as induced for example by vibration or the protective film on the metal surfaces is removed by the rubbing action
Fretting Corrosion
selective corrosion in the grain boundaries of a metal or alloy w/o appreciable attack on the grains or crystals themselves; when severe, this attack causes a loss of strength& ductility out of proportion to the amount of metal actually destroyed by corrosion
Intergranular Corrosion
resulting corrosion when microbial natural activities create oxidizing, reducing, acidic, or other conditions under w/c 1 form of ametal or material of construction is chemically transformed to another
Microbiological Influenced Corrosion (MIC)
can be minimized by electrochemical method of corrosion control has found wide application in the protection of carbon steel underground structures such as pipelines& tanks from external soil corrosion; 2 methods of providing cathodic protection are sacrificial-anode method & impressed-emf method
Galvanic Corrosion
use of inhibitors as additives is an important means of combating corrosion; inhibitors will decrease corrosion of metals in the environment, the effectiveness of a given inhibitor generally increases w/ an increase in concentration of inhibitor; the amount off inhibitor present is critical in that a deficiency may result to this type
Pitting Corrosion
