API 571 High Temperature Corrosion 2

Question 1

The Couper-Gorman curves extend McConomy curves by accounting for what additional factor?

Accepted Answer

Effect of hydrogen partial pressure on H2S corrosion rates

Answer

Effect of temperature on sulfidation

Answer

Effect of flow velocity on erosion-corrosion

Answer

Effect of chlorides on alloy selection

Question 2

In which type of steel does sigma phase embrittlement occur, and at what temperature range?

Accepted Answer

Austenitic and duplex stainless steels between 600–1000°F

Answer

Carbon steels above 500°F

Answer

Low-alloy Cr-Mo steels in hydrogen service

Answer

Aluminum alloys at any temperature

Question 3

885°F (475°C) embrittlement is a damage mechanism primarily affecting which steel family?

Accepted Answer

Ferritic and duplex stainless steels

Answer

Austenitic stainless steels

Answer

Carbon and low-alloy steels

Answer

Nickel-base superalloys

Question 4

Which inspection method is most effective for detecting High Temperature Hydrogen Attack (HTHA)?

Accepted Answer

Advanced ultrasonic testing (TOFD or phased array)

Answer

Magnetic particle testing

Answer

Dye penetrant testing

Answer

Hydrostatic pressure testing

Question 5

Temper embrittlement in Cr-Mo steels occurs primarily during which condition?

Accepted Answer

Slow cooling or extended hold in the 700–1050°F range

Answer

Rapid quenching from austenitizing temperature

Answer

Welding at high heat input

Answer

Service at temperatures above 1200°F

Question 6

Which of the following is NOT considered a high-temperature damage mechanism in API 571?

Accepted Answer

Chloride stress corrosion cracking

Answer

Carburization

Answer

Nitriding

Answer

Fuel ash corrosion