API653 API571 Flashcards
What is brittle fracture? Definition, susceptible temp, and affect metal (2)?
Brittle fracture is the sudden rapid fracture under stress where the material exhibits little or no
evidence of ductility or plastic deformation.
Under 60F
Affected material:
- Carbon steels and low alloy steels are of prime concern, particularly oldersteels.
- 400 series stainless steels are also susceptible.
What is mechanical fatigue? Definition and affected metal
Fatigue cracking is a mechanical form of degradation that occurs when a component is exposed to cyclical stresses for an extended period. These stresses can arise from either mechanical loading or thermal
cycling
Affected metal: All engineering alloys are subject to fatigue cracking, although the stress levels and number of cycles necessary to cause failure vary by material
What it atm corrosion? Definition and affected metal (3)
occurs from moisture associated with atmospheric
conditions. Marine environments and moist polluted industrial environments with airborne contaminants are most severe. Dry rural environments cause
very little corrosion.
Affected metal:
a. Carbon Steel
b. Low alloy steels
c. Copper alloyed aluminum
What is CUI? Affected metal (4)
a. Carbon steel
b. Low alloy steels
c. 300 series stainless steel
d. Duplex stainless steel
What is MIC?Definition and affected metal (7)
corrosion caused by living organisms such as bacteria, algae or fungi.
Affected metal :
a. Carbon steel
b. Low allow steel
c. 300 series stainless steel
d. 400 series stainless steel
e. Aluminum
f. Copper
g. Some nickel based alloys
What is soil corrosion, Definition and affected metal (3)
deterioration of metals exposed to soils is referred to as a soil corrosion
a. Carbon steel
b. Cast iron
c. Ductile iron
What is caustic corrosion?Definition and affected metal (3)
Localized corrosion due to the concentration of caustic or Alkaline salts that
usually occurs under evaporative or high Heat transfer conditions.
carbon steel, low alloy steels and 300 Series SS
What is CL-SCC?affected metal (3)
Surface initiated cracks caused by environmental cracking of 300 series stainless steel and some nickel base alloys under the combined action of
tensile stress, temperature and an aqueous chloride environment
a. All 300 series stainless steels are highly susceptible
b. Duplex stainless steels are more resistant
c. Nickel base alloys are highly resistant
What is Caustic SCC? affected metal (4)
Caustic embrittlement is a form of stress corrosion cracking characterized by surface-initiated cracks that occur in piping and equipment exposed to caustic,
primarily adjacent to non-PWHT’d welds
a. Carbon steel
b. Low alloy steels
c. 300 series stainless steel
Nickel base alloys are more resistant.
What is Sour water corrosion?
Corrosion of steel (primarily) due to acidic sour water (SW) containing H2S at a pH between 4.5 and 7.0.
a) Primarily affects carbon steel.
b) Stainless steels, copper alloys, and nickel-based alloys are usually resistant.
What is sulfuric acid corrosion? affected metal (6)
Sulfuric acid promotes general and localized corrosion of carbon steel and other alloys. Carbon steel heat affected zones may experience severe
corrosion
a. Carbon steel
b. 316L SS
c. Alloy 20
d. High silicon cast iron
e. High nickel cast iron
f. Alloy B-2
CUI temperature suspectible?
- 10-350 (CS/low alloy steel/400SS)
- 140-350 (300SS)
- 280-350 (duplex sS)
Affected material of thermal shock?
all metals and alloy
What PWHT temperature could prevent caustic stress corrosion cracking
1150F
carburization can occur at what temp in CS?
Above 1100F
