API 574 (Inspection Practices for Piping System Components) Flashcards
API 574
CUI affects carbon steel and low alloy piping at what temperature range (Corrosion)?
API 574 (7) Inspection Plans
(7.4) Inspection for Specific Damage Mechanisms
(7.4.4) CUI
(7.4.4.1) Insulated Piping Systems Susceptible to CUI
(7.4.4.1.e) 10-350 degrees
Carbon steel piping systems, including ones insulated for personnel protection, operating between 10°F(–12°C) and 350 °F (175 °C); CUI is particularly aggressive where operating temperatures cause frequent or continuous condensation and reevaporation of atmospheric moisture;
API 574
What is the distance to dig when inspecting for Soil-to-Air corrosion (Corrosion)?
API 574 (7) Inspection Plans (7.4) Inspection for Specific Damage Mechanisms (7.4.5) Soil-to-air (S/A) Interface 6"-12" Inspection at grade should include checking for coating damage, bare pipe, and pit depth measurements. If significant corrosion is noted, thickness measurements and excavation may be required to assess whether the corrosion is localized to the S/A interface or can be more pervasive to the buried system. Thickness readings at S/A interfaces can expose the metal and accelerate corrosion, if coatings and wrappings are not properly restored. Figure 23 is an example of corrosion at a S/A interface although it had been wrapped with tape. If the buried piping has satisfactory cathodic protection as determined by monitoring in accordance with API 570, excavation is required only if there is evidence of coating or wrapping damage. If the buried piping is uncoated at grade, consideration should be given to excavating 6 in. (150 mm) to 12 in. (300 mm) deep to assess the potential for hidden damage. Alternately, specialized UT techniques such as guided wave can be used to screen areas for more detailed evaluation. At concrete-to-air and asphalt-to-air interfaces for buried piping without cathodic protection, the inspector should look for evidence that the caulking or seal at the interface has deteriorated and allowed moisture ingress. If such a condition exists on piping systems over 10 years old, it may be necessary to inspect for corrosion beneath the surface before resealing the joint. See API 571 for additional information on corrosion at S/A interfaces.
API 574
CUI affects Austenitic stainless steels at what temperature range (Corrosion)?
API 574 (7) Inspection Plans
(7.4) Inspection for Specific Damage Mechanisms
(7.4.4) CUI
(7.4.4.1) Insulated Piping Systems Susceptible to CUI
(7.4.4.1.h)
120°F and 400°F
Austenitic stainless steel piping systems operating between 120°F (60 °C) and 400°F (205 °C) (susceptible to chloride SCC)
API 574
What is the starting temperature for Sulfidation on Carbon Steel piping per API 574 (Corrosion)?
API 574 (7) Inspection Plans
(7.4) Inspection for Specific Damage Mechanisms
(7.4.6) Service-specific and Localized Corrosion
(7.4.6.2) There are many types of internal corrosion possible from the process service. These types of corrosion are usually localized, and are specific to the service.
(7.4.6.2.j)
450°F
Mixed grades of carbon steel piping in hot corrosive oil service [450°F (232°C)] or higher temperature and sulfur content in the oil greater than 0.5 % by weight);
NOTE: Nonsilicon-killed steel pipe (e.g. ASTM A53 and API 5L) can corrode at higher rates than silicon-killed steel pipe (e.g. ASTM A106) in high-temperature sulfidation environments.
API 574
What is the temperature range causing temper embrittlement in low chromes (Corrosion)?
API 574 (3) Terms, Definitions, Acronyms, and Abbreviations
(3.1) Terms and Definitions
(3.1.39)
650°F to 1100°F
The reduction in toughness due to a metallurgical change that can occur in some low-alloy steels, e.g. 2 1/4 Cr-1Mo, as a result of long term exposure in the temperature range of about 650 °F to 1100 °F (345 °C to 595 °C).
API 574
What is the maximum temperature for taking UT readings per API 574 (NDE)?
API 574 (10) Inspection Procedures and Practices
(10.2) Thickness Measurements
(10.2.1) Ultrasonic Examination Techniques (UTs)
(10.2.1.5) High-temperature Thickness Measurements
(10.2.1.5.1)
Up to 1100 °F (593 °C)
The search unit is the most important component of the thickness testing equipment for high-temperature measurements. Some high-temperature search units are designed to withstand temperatures up to 1000 °F (538 °C). Special delay-line materials and water-cooled transducers are available that permit the use of pulse-echo instruments at temperatures up to 1100 °F (593 °C).The majority of high-temperature dual-element search units are manufactured with the delay material built into the case, while most single-element search units come with replaceable delays.
API 574
What material is subject to temper embrittlement (Materials)?
API 574 (7) Inspection Plans Inspection for Specific Damage Mechanisms
(7.4) Inspection for Specific Damage Mechanisms
(7.4.12) Brittle Fracture
(7.4.12.1)
Low Chromes
Carbon, low-alloy, and other ferritic steels can be susceptible to brittle failure at or below ambient temperatures. In some cases, the refrigerating effect of vaporizing liquids such as ammonia or C2 or C3 hydrocarbons can chill the piping and promote brittle fracture in material that may not otherwise fail. Brittle fracture usually is not a concern with relatively thin wall piping. Most brittle fractures have occurred on the first application of a particular stress level (that is, the first hydrotest or overload) unless critical defects are introduced in service. The potential for a brittle failure should be considered when pressure testing or more carefully evaluated when pressure testing equipment pneumatically or when adding any other additional loads. Special attention should be given to low-alloy steels (especially 2 1/4 Cr-1 Mo material), because they can be prone to temper embrittlement, and to ferritic stainless steels.
API 574
What material is subject to chloride stress-corrosion cracking (Material)?
API 574 (7) Inspection Plans
(7.4) Inspection for Specific Damage Mechanisms
(7.4.8) Environmental Cracking
(7.4.8.1) Piping system materials of construction are normally selected to resist the various forms of SCC. Some piping systems can be susceptible to environmental cracking due to upset process conditions, CUI, unanticipated condensation, or exposure to wet hydrogen sulfide or carbonates. Examples of this include the following.
(7.4.8.1.a)
300 SS
Chloride SCC of austenitic stainless steels resulting from moisture and chlorides under insulation, under deposits, under gaskets, or in crevices.
API 574
Common material subject to temper embrittlement (Material)?
API 574 (7) Inspection Plans
(7. 4) Inspection for Specific Damage Mechanisms
(7. 4.12) Brittle Fracture
(7. 4.12.1) Carbon, low-alloy, and other ferritic steels can be susceptible to brittle failure at or below ambient temperatures. In some cases, the refrigerating effect of vaporizing liquids such as ammonia or C2 or C3 hydrocarbons can chill the piping and promote brittle fracture in material that may not otherwise fail. Special attention should be given to low-alloy steels (especially 2 1/4 Cr-1 Mo material), because they can be prone to temper embrittlement, and to ferritic stainless steels.
API 574
What material is subject to polythionic acid stress-corrosion cracking (Material)?
API 574 (7) Inspection Plans
(7.4) Inspection for Specific Damage Mechanisms
(7.4.8) Environmental Cracking
(7.4.8.1) Piping system materials of construction are normally selected to resist the various forms of SCC. Some piping systems can be susceptible to environmental cracking due to upset process conditions, CUI, unanticipated condensation, or exposure to wet hydrogen sulfide or carbonates. Examples of this include the following.
(7.4.8.1.b)
Sensitized 300 SS
Polythionic acid SCC of sensitized austenitic alloy steels resulting from exposure to sulfide/moisture condensation/oxygen.
