API RP 571 3.17 Chloride Stress
Corrosion Cracking Exam Questions
and Answers (Latest Update 2026)
3.17.1 Description of Damage -
correct answer ✅Surface initiated cracking of 300 series SS and
some nickel-based alloys under the combined action of tensile
stress, temperature, and an aqueous chloride environment. It is
also referred to as chloride cracking.
3.17.2 Affected Materials -
correct answer ✅a) All 300 series SS are highly susceptible. Welds
in 300 series SS normally contain some ferrite, producing a duplex
structure that is usually more resistant to chloride stress corrosion
cracking (Cl-SCC) than the base metal
b) Duplex stainless steels are more resistant but still susceptible.
c) Nickel-based alloys are highly resistant but not immune.
3.17.3 Critical Factors -
correct answer ✅a) Chloride content, temperature, pH, tensile
stress, presence of oxygen, and alloy composition are critical
factors.
b) Cl-SCC is caused by the inorganic chloride ion (Cl-) (or other
inorganic halide ions such as bromide, in which case it might be
named differently). Organic chlorides will not directly cause Cl-SCC,
but they can, and typically do, produce ionic, inorganic chlorides by
, API RP 571 3.17 Chloride Stress
Corrosion Cracking Exam Questions
and Answers (Latest Update 2026)
the processes of hydrolysis or thermal decomposition (pyrolisis).
Therefore, organic chlorides can lead to Cl-SCC.
c) Increasing levels of chloride increase the likelihood of cracking.
1. No practical lower limit for chlorides exists because of the
potential for chlorides to concentrate. For example, heat transfer
conditions, as on the surface of exchanger tubes, significantly
increase cracking potential. Repetitive wetting and drying
situations, including alternating steam and water, can also lead to
cracking.
2. Non-condensing systems will be a particular concern, because
the chlorides cannot be removed with the water phase.
d) Increasing temperatures increase the potential for cracking, as
long as the other required elements (stress and aqueous chloride
solution) are present concurrently.
1. Although there are exceptions at lower temperatures and even
ambient temperature, particularly with highly cold worked or
sensitized materials, cracking usually occurs at metal temperatures
above about 140°F (60°C), and experience has shown this to be a
useful temperature limit guideline for fixed equipment in the
refining industry.
e) The potential for cracking increases at lower pH; however, SCC
usually does not occur at pH values below 2. At these lower pH
Corrosion Cracking Exam Questions
and Answers (Latest Update 2026)
3.17.1 Description of Damage -
correct answer ✅Surface initiated cracking of 300 series SS and
some nickel-based alloys under the combined action of tensile
stress, temperature, and an aqueous chloride environment. It is
also referred to as chloride cracking.
3.17.2 Affected Materials -
correct answer ✅a) All 300 series SS are highly susceptible. Welds
in 300 series SS normally contain some ferrite, producing a duplex
structure that is usually more resistant to chloride stress corrosion
cracking (Cl-SCC) than the base metal
b) Duplex stainless steels are more resistant but still susceptible.
c) Nickel-based alloys are highly resistant but not immune.
3.17.3 Critical Factors -
correct answer ✅a) Chloride content, temperature, pH, tensile
stress, presence of oxygen, and alloy composition are critical
factors.
b) Cl-SCC is caused by the inorganic chloride ion (Cl-) (or other
inorganic halide ions such as bromide, in which case it might be
named differently). Organic chlorides will not directly cause Cl-SCC,
but they can, and typically do, produce ionic, inorganic chlorides by
, API RP 571 3.17 Chloride Stress
Corrosion Cracking Exam Questions
and Answers (Latest Update 2026)
the processes of hydrolysis or thermal decomposition (pyrolisis).
Therefore, organic chlorides can lead to Cl-SCC.
c) Increasing levels of chloride increase the likelihood of cracking.
1. No practical lower limit for chlorides exists because of the
potential for chlorides to concentrate. For example, heat transfer
conditions, as on the surface of exchanger tubes, significantly
increase cracking potential. Repetitive wetting and drying
situations, including alternating steam and water, can also lead to
cracking.
2. Non-condensing systems will be a particular concern, because
the chlorides cannot be removed with the water phase.
d) Increasing temperatures increase the potential for cracking, as
long as the other required elements (stress and aqueous chloride
solution) are present concurrently.
1. Although there are exceptions at lower temperatures and even
ambient temperature, particularly with highly cold worked or
sensitized materials, cracking usually occurs at metal temperatures
above about 140°F (60°C), and experience has shown this to be a
useful temperature limit guideline for fixed equipment in the
refining industry.
e) The potential for cracking increases at lower pH; however, SCC
usually does not occur at pH values below 2. At these lower pH
