HSE 2 Flashcards
Corrosion
Caused by a chemical or electrochemical attack on the surface of the metals.
How to lessen scaling?
*Increase velocity
*Use strainers
*Wash using steam condensate
Factors affecting corrosion
*Purity of metal
*Temperature
*Exposure to moisture and acids
TYPES OF CORROSION:
Galvanic / Fretting
When two electrochemically dissimilar metals are in electrical contact in an electrolytic environment
TYPES OF CORROSION:
Pitting
*Most destructive
*Redox Reaction causing giants pits
*Metal relocates to cathodic metal film
TYPES OF CORROSION:
Crevice
*Localized
*Difference in ion concentrations in two areas of metal
TYPES OF CORROSION:
Intergranular
*Caused by impurities at grain boundaries (crystalities) of solid
TYPES OF CORROSION:
Stress Corrosion Cracking
*Tensile stress + corrosive environment
TYPES OF CORROSION:
Uniform
*Most common form
*Attack across the surface of metal
TYPES OF CORROSION:
Corrosion Fatigue
Repeated application of stress
Erosion
Wear of the pump internal parts by suspended solid particles contained in the fluid being pumped.
Fire Point
Lowest temperature at which oil vapor will BURN after exposure to OPEN FLAME
Smoke Point
Lowest temperature at which oil will produce VISIBLE SMOKE
Flash Point
Lowest temperature at which OIL EVAPORATES to form COMBUSTIBLE GAS CONCENTRATION
Pour Point
Lowest temperature at which the oil will pour
Boiling Point
Temperature at which vapor pressure of a liquid is equal to the pressure of the atmosphere on the liquid
Auto-ignition Temperature
Temperature at which liquid readily ignites at atmospheric pressure
Equipment Cost by Scaling
Six-Tenths Rule
(Big Cost) / (Small Cost) = (Big Size / Small Size)^0.6
DCS vs PLC
DCS
*Regulatory actions
*Alarms
*Used for Basic Process Control System
PLC
*Discrete control
*Alarms
*Used for Safety Instrumented system
WAYS TO DISPOSE:
*Liquids
*Gases
*Liquids
-Drain
-Ground
-Vessel in ground
*Gases
-Atmosphere (Innocent)
-Flare (Combustible)
-Scrubber (Absorbable)
FEEDBACK CONTROL
*What is measured?
-manipulated variable
*When is error adjusted?
-AFTER error is propagated
*Closed or Open Loop?
-closed loop
FEEDFORWARD CONTROL
*What is measured?
-disturbance variable
*When error is adjusted?
-BEFORE error is propagated
*Closed or Open Loop?
-open loop
Ratio Control
*Setpoint determined by another sensor
*Setpoint calculated by equation