QUESTIONS AND ANSWERS
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This recommended practice discusses damage mechanisms applicable to oil refineries; however, much
of the information herein can also be applied to petrochemical and other industrial applications, as the
user deems appropriate. It is up to the user determine the applicability and appropriateness of the
information contained herein as it applies to their facility.
API 571 is a reference document that provides useful information by itself and also complements other
API standards and recommended practices. The document should be utilized as a reference to other
integrity related documents. It is intended to contribute to the overall management of pressure
equipment integrity and is a useful resource for many mechanical integrity program activities including:
a) identification of existing damage or deterioration and anticipated rates of degradation,
b) identification of future damage mechanism susceptibilities,
c) develo - correct answers 1 Scope
Terms and Definitions - correct answers 2
For the purposes of this document, the following definitions apply. - correct answers 2.1 Definitions
A term that refers to a type of metallurgical structure (austenitic) normally found in 300 series stainless
steel (SS) and nickel-based alloys. These materials have a face centered cubic crystallographic structure
and are generally nonmagnetic. - correct answers 2.1.1 austenitic
The 300 series SS, which commonly include Types 304, 304L, 304H, 309, 310, 316, 316L, 317, 317L, 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. - correct answers 2.1.2 austenitic
stainless steels
, An alloy consisting primarily of iron (Fe) with a small amount of carbon (C). Carbon steels do not have
alloying elements intentionally added. However, there may be small amounts of elements permitted by
specifications such as ASTM A516 and ASTM A106, for example, that can affect corrosion-related
properties, hardiness after welding, and toughness. Elements that may be found in small quantities
include Mn, Cr, Ni, Mo, Cu, S, Si, P, Al, V, and B. - correct answers 2.1.3 carbon steel
Chemical used in amine treating to remove H2S and CO2 from hydrocarbon streams. - correct answers
2.1.4 diethanolamine (DEA)
Chemical used in amine treating to remove H2S and CO2 from hydrocarbon streams. - correct answers
2.1.5 diglycolamine (DGA)
A family of stainless steels that contain a mixed austenitic-ferritic structure including Alloys 2205, 2304,
and 2507. The welds of 300 series SS may also exhibit a duplex structure. - correct answers 2.1.6 duplex
stainless steel
A term that refers to a type of metallurgic structure (ferrite) normally found in carbon and low-ally steels
and many 400 series SS. These materials have a body centered cubic crystallographic structure and are
generally magnetic. - correct answers 2.1.7 ferritic
A family of stainless steels including Types 405, 409, 410S, 430, 442, and 446. - correct answers 2.1.8
ferritic stainless steels
The portion of the base metal adjacent to a weld that has not been melted, but in which the
metallurgical microstructure and mechanical properties have been changed by the heat of welding,
sometimes with undesirable effects. - correct answers 2.1.9 heat-affected zone (HAZ)
A family of carbon steels in which higher strength levels are achieved by the addition of moderate
amounts of alloying elements such as titanium, vanadium, or nioblum in amounts of less than 0.1%.
They can be more sensitive to cracking during fabrication from hydrogen embrittlement (HE) (delayed
cracking; also known as underbead cracking). - correct answers 2.1.10 high-strength low-alloy steel
(HSLA steel)
A family of steels containing up to 9% chromium and other alloying additions for high temperature
strength and creep resistance. The low-alloy steels commonly encountered in refining include C-0.5Mo,