API 571 Exam Questions and Answers Latest Update 2025-2026
Austenitic - Answers a term that refers to a type of metallurgical structure (austenite) normally
found in
300 Series stainless steels and nickel base alloys.
Austenitic Stainless Steel - Answers The 300 series stainless steels including Types 304, 304L,
304H, 309, 310, 316, 316L, 316H, 321, 321H, 347, and 347H. The "L" and "H" suffixes refer to
controlled ranges of low and high carbon content, respectively. These alloys are characterized
by an austenitic structure.
Carbon Steel - Answers steels that do not have alloying elements intentionally added. However,
there
may be small amounts of elements permitted by specifications such as SA516 and SA106, for
example that can affect corrosion resistance, hardness after welding, and toughness. Elements
which may be found in small quantities include Cr, Ni, Mo, Cu, S, Si, P, Al, V and B.
Diethanolamine (DEA) - Answers used in amine treating to remove H2S and CO2 from
hydrocarbon streams.
Duplex stainless steel - Answers a family of stainless steels that contain a mixed austenitic-
ferritic structure including Alloy 2205, 2304, and 2507. The welds of 300 series stainless steels
may also exhibit
a duplex structure.
Ferritic - Answers a term that refers to a type of metallurgical structure (ferrite) normally found
in carbon
and low alloy steels and many 400 series stainless steels.
Ferritic Stainless Steel - Answers Includes types 405, 409, 430, 442, and 446
Heat Affected Zone (HAZ) - Answers The portion of the base metal adjacent to a weld which
has not been melted, but the metallurgical microstructure and mechanical properties have been
changed by the heat of welding, sometimes with undesirable effects.
High Strength low Alloy Steels (HSLA) - Answers A family of low-carbon steels in which the
strength levels are achieved by the addition of moderate amounts of alloying elements such as
titanium, vanadium or niobium in amounts of less than 0.1 percent. They can be more sensitive
to cracking during fabrication from hydrogen embrittlement (delayed cracking) or underbead
cracking.
Hydrogen Induced Cracking (HIC) - Answers describes stepwise internal cracks that connect
adjacent hydrogen blisters on different planes in the metal, or to the metal surface. No
, externally applied stress is needed for the formation of HIC. The development of internal cracks
(sometimes referred to as blister cracks) tends to link with other cracks by a transgranular
plastic shear mechanism because of internal pressure resulting from the accumulation of
hydrogen. The link-up of these cracks on different planes in steels has been referred to as
stepwise cracking to characterize the nature of the crack appearance.
Low alloy steel - Answers a family of steels containing up to 9% chromium and other alloying
additions for high temperature strength and creep resistance. The materials include C-0.5 MO,
MN-0.5MO,1Cr-0.5MO,1.25Cr-0.5MO,2.25Cr-1.0MO, 5Cr-0.5MO, and 9Cr-1.0MO. These are
considered ferritic steels.
Martensitic - Answers a term that refers to a type of metallurgical structure (martensite)
normally found in
some 400 series stainless steel. Heat treatment and or welding followed by rapid cooling can
produce this structure in carbon and low alloy steels.
Martensitic stainless steel - Answers include Types 410, 410S, 416, 420, 440A, 440B, and 440C.
Methyldiethanolamine (MDEA) - Answers used in amine treating to remove H2S and CO2 from
hydrocarbon streams.
Monoethanolamine (MEA) - Answers used in amine treating to remove H2S and CO2 from
hydrocarbon streams.
Nickel base - Answers a family of alloys containing nickel as a major alloying element (>30%)
including
Alloys 200, 400, K-500, 800, 800H, 825, 600, 600H, 617, 625, 718, X-750, and C276.
Stress oriented hydrogen induced cracking (SOHIC) - Answers describes an array of cracks,
aligned nearly perpendicular to the stress, that are formed by the link-up of small HIC cracks in
steel. Tensile strength (residual or applied) is required to produce SOHIC. SOHIC is commonly
observed in the base
metal adjacent to the Heat Affected Zone (HAZ) of a weld, oriented in the through-thickness
direction. SOHIC may also be produced in susceptible steels at other high stress points, such as
from the tip of the mechanical cracks and defects, or from the interaction among HIC on
different planes in the steel.
Stainless Steel - Answers there are four categories of stainless steels that are characterized by
their
metallurgical structure at room temperature: austenitic, ferritic, martensitic and duplex. These
alloys have varying amounts of chromium and other alloying elements that give them resistance
to oxidation, sulfidation and other forms of corrosion depending on the alloy content.
Austenitic - Answers a term that refers to a type of metallurgical structure (austenite) normally
found in
300 Series stainless steels and nickel base alloys.
Austenitic Stainless Steel - Answers The 300 series stainless steels including Types 304, 304L,
304H, 309, 310, 316, 316L, 316H, 321, 321H, 347, and 347H. The "L" and "H" suffixes refer to
controlled ranges of low and high carbon content, respectively. These alloys are characterized
by an austenitic structure.
Carbon Steel - Answers steels that do not have alloying elements intentionally added. However,
there
may be small amounts of elements permitted by specifications such as SA516 and SA106, for
example that can affect corrosion resistance, hardness after welding, and toughness. Elements
which may be found in small quantities include Cr, Ni, Mo, Cu, S, Si, P, Al, V and B.
Diethanolamine (DEA) - Answers used in amine treating to remove H2S and CO2 from
hydrocarbon streams.
Duplex stainless steel - Answers a family of stainless steels that contain a mixed austenitic-
ferritic structure including Alloy 2205, 2304, and 2507. The welds of 300 series stainless steels
may also exhibit
a duplex structure.
Ferritic - Answers a term that refers to a type of metallurgical structure (ferrite) normally found
in carbon
and low alloy steels and many 400 series stainless steels.
Ferritic Stainless Steel - Answers Includes types 405, 409, 430, 442, and 446
Heat Affected Zone (HAZ) - Answers The portion of the base metal adjacent to a weld which
has not been melted, but the metallurgical microstructure and mechanical properties have been
changed by the heat of welding, sometimes with undesirable effects.
High Strength low Alloy Steels (HSLA) - Answers A family of low-carbon steels in which the
strength levels are achieved by the addition of moderate amounts of alloying elements such as
titanium, vanadium or niobium in amounts of less than 0.1 percent. They can be more sensitive
to cracking during fabrication from hydrogen embrittlement (delayed cracking) or underbead
cracking.
Hydrogen Induced Cracking (HIC) - Answers describes stepwise internal cracks that connect
adjacent hydrogen blisters on different planes in the metal, or to the metal surface. No
, externally applied stress is needed for the formation of HIC. The development of internal cracks
(sometimes referred to as blister cracks) tends to link with other cracks by a transgranular
plastic shear mechanism because of internal pressure resulting from the accumulation of
hydrogen. The link-up of these cracks on different planes in steels has been referred to as
stepwise cracking to characterize the nature of the crack appearance.
Low alloy steel - Answers a family of steels containing up to 9% chromium and other alloying
additions for high temperature strength and creep resistance. The materials include C-0.5 MO,
MN-0.5MO,1Cr-0.5MO,1.25Cr-0.5MO,2.25Cr-1.0MO, 5Cr-0.5MO, and 9Cr-1.0MO. These are
considered ferritic steels.
Martensitic - Answers a term that refers to a type of metallurgical structure (martensite)
normally found in
some 400 series stainless steel. Heat treatment and or welding followed by rapid cooling can
produce this structure in carbon and low alloy steels.
Martensitic stainless steel - Answers include Types 410, 410S, 416, 420, 440A, 440B, and 440C.
Methyldiethanolamine (MDEA) - Answers used in amine treating to remove H2S and CO2 from
hydrocarbon streams.
Monoethanolamine (MEA) - Answers used in amine treating to remove H2S and CO2 from
hydrocarbon streams.
Nickel base - Answers a family of alloys containing nickel as a major alloying element (>30%)
including
Alloys 200, 400, K-500, 800, 800H, 825, 600, 600H, 617, 625, 718, X-750, and C276.
Stress oriented hydrogen induced cracking (SOHIC) - Answers describes an array of cracks,
aligned nearly perpendicular to the stress, that are formed by the link-up of small HIC cracks in
steel. Tensile strength (residual or applied) is required to produce SOHIC. SOHIC is commonly
observed in the base
metal adjacent to the Heat Affected Zone (HAZ) of a weld, oriented in the through-thickness
direction. SOHIC may also be produced in susceptible steels at other high stress points, such as
from the tip of the mechanical cracks and defects, or from the interaction among HIC on
different planes in the steel.
Stainless Steel - Answers there are four categories of stainless steels that are characterized by
their
metallurgical structure at room temperature: austenitic, ferritic, martensitic and duplex. These
alloys have varying amounts of chromium and other alloying elements that give them resistance
to oxidation, sulfidation and other forms of corrosion depending on the alloy content.
