API 571 Flashcards
Amine Stress Corrosion Cracking - most often found at? and appearance
- found at or adjacent to non-postweld-heat-treated carbon steel welds or in
highly cold worked parts. - localized corrosion
Amine Stress Corrosion Cracking-Affected Material?
Carbon steel and low-alloy steels.
ATMOspheric Corrosion-description?
Corrosion that occurs from moisture associated with atmospheric conditions. Marine environments and moist, polluted industrial environments with airborne contaminants are the most severe.
Atmospheric Corrosion-Affected Material?
Carbon steel, low-alloy steels, and copper alloyed aluminum
Boiler Water and Stream Condensate Corrosion-due to?
result of dissolved oxygen and/or carbon dioxide, Flow accelerated corrosion (FAC) in these systems may occur either as general wall thinning corrosion or localized corrosion at high velocity, high turbulence, or change of flow direction locations
Boiler Water and Stream Condensate Corrosion-Affected Material?
Carbon steel and low-alloy steels.
Caustic Corrosion-Affected Material?
Primarily carbon steel, low-alloy steels, and 400 series SS.
Caustic Corrosion-likely to occur at what temp?
In high-solution-strength caustic, temperatures above about 170 °F (75 °C)
Caustic Corrosion-damage appearance?
Caustic gouging is typically characterized by localized metal loss,
Caustic Stress Corrosion Cracking
equipment exposed to caustic at elevated temperature, primarily adjacent to non-PWHT’d welds.
Caustic Stress Corrosion Cracking-Affected Material?
Carbon steel, low-alloy steels, and 300 series SS are susceptible.
Caustic Stress Corrosion Cracking-Prevention/Mitigation
A heat treatment at 1150 °F (620 °C) minimum with a minimum holding time of 1 hr is considered an effective stress relieving heat treatment for carbon steel.
Corrosion Under Insulation-critical factors (temps)
- carbon steel, low-alloy steel, and 400 series SS equipment operating between 10 °F (−12 °C) and 350 °F (175 °C).
- For 300 series SS, where Cl− SCC is the concern, refiners generally focus on the temperature range of
140 °F (60 °C) to 350 °F (175 °C). - or duplex stainless steel, where Cl− SCC is the concern, refiners generally focus on the temperature
range of 280 °F (140 °C) to 350 °F (175 °C).
Corrosion Under Insulation-Affected Material?
Carbon steel, low-alloy steels, 300 series SS, 400 series SS, and duplex stainless steels.
Sulfidation-damage description?-Affected Material?
carbon steel, low-alloy steels, 400 series SS, and 300 series SS. Nickel-based alloys
NOT ALUMINUM
Sulfidation-Inspection and Monitoring?
UT thickness measurement or RT
Thermal Fatigue-appearance of damage
dagger shaped, transgranular, and oxide filled, transverse
Erosion/Erosion – Corrosion-Affected Material?
All metals, but mostly carbon steel and copper alloys in refining. Refractories are also affected.
aluminum susceptible too
Erosion/Erosion – appearance of damage
localized loss in thickness in the form of
grooves, gullies, waves, rounded holes, valleys,
Hydrochloric Acid Corrosion-affected materials
all common materials
Mechanical Fatigue (Including Vibration-induced Fatigue) - appearance of damage
clam shapes / beach marks
Galvanic corrosion-damage appearance (3)
crevic, groove or pitting
Galvanic corrosion-affect metal?
all metals except noble metals
Corrosion Under Insulation-appearance (3)
loose flaky scale, pitting, localized thickness loss
Microbiologically Influenced Corrosion-description of damage
Corrosion caused by living organisms such as bacteria, algae, or fungi.
Microbiologically Influenced Corrosion-affect metal?
carbon and alloy steels, 300 series SS and 400 series SS, aluminum alloys, copper alloys, and some nickel alloys.
Titanium appears to be highly resistant.
Microbiologically Influenced Corrosion-affect equipments
MIC is often found in water-cooled heat exchangers,
low flow i
Microbiologically Influenced Corrosion-damage appearance (3)
localized pitting under deposits or tubercles that shield the organisms.
AND
Cup shapes pits
Soil Corrosion-affected metals
Carbon steel, cast iron, and ductile iron.
Soil Corrosion-damage appearance (2)
localized pitting, thinning
Sulfidation-Appearance (2)
uniform thinning, high velocity erosion/corrosion
Corrosion rates increase with increasing metal temperature up to the point where the water evaporates quickly at wat temp?
212F
CUI is most severe at?
above 212F
Boiler Water and Stream Condensate Corrosion-damage appearance
pitting
chloride SCC method of inspection
PT and Phase analysis eddy current
chloride SCC - nickel content % = highly resistant?
Alloys with nickel contents above 35 % are highly resistant
brittle fracture - affect metals
CS, low alloys, 400 SS
thermal fatigue/ mechanical fatigue- affected metals
all metals
resistance to sulfidation increase with?
chromium
fatigue cracking cause by high cycle fatigue can be difficult to detect b/c
time between crack initiation and failure is too short
brittle fracture occurs (2)
- less than 8ksi
2. greater than 25% of test pressure
threaded connections are especially susceptible to ?
boiler water and steam condensate
atm corrosion rate increase with metal temp (F)
up 250F
what is resistance to chloride cracking
nickel based
size of the fillet weld name is
leg
sulfication accelerate by the presense
of hydrogen
hydrochloric acid increase with increasing
temp
chloride stress corrosion cracking occurs above
140F
predominate factor for mechanical fatigue
surface notices
BNH
Carbon Steel 200 C-1/2 Mo 225 1-1/4 Cr-1/2 Mo 225 2-1/4 Cr-1 Mo 241 5, 7, 9, Cr-Mo 241 12 Cr 241
Best inspection for CSS
phase array and PT
