API 571 High Temperature Corrosion

Question 1

What is the primary driving force for high-temperature oxidation of metals?

Accepted Answer

Elevated partial pressure of oxygen at high temperature

Answer

High-temperature oxidation occurs when metals react with oxygen at elevated temperatures, with the rate increasing with oxygen partial pressure and temperature.

Question 2

Above what temperature does carbon steel begin to experience significant oxidation and scaling?

Accepted Answer

900°F (482°C)

Answer

Carbon steel begins to form significant oxide scale and suffer measurable metal loss due to oxidation above approximately 900°F (482°C).

Question 3

What is the primary effect of carburization on steel?

Accepted Answer

Absorption of carbon increasing hardness and causing embrittlement

Answer

Carburization causes carbon absorption into the metal, significantly increasing hardness but severely reducing toughness and ductility of the affected material.

Question 4

Which process involves carbon loss from steel in high-temperature hydrogen-rich atmospheres?

Accepted Answer

Decarburization

Answer

Decarburization occurs when hydrogen at high temperature reacts with carbon in steel, reducing surface hardness and strength over time.

Question 5

Above what temperature does sulfidation corrosion by H2S become significant in refinery streams?

Accepted Answer

500°F (260°C)

Answer

Sulfidation corrosion by hydrogen sulfide becomes significant above approximately 500°F (260°C) where H2S reacts aggressively with iron to form iron sulfide scale.

API 571 - API 571 Corrosion and Materials Practice Test

API 571 - API 571 Corrosion and Materials Practice Test

API 571 High Temperature Corrosion