API 571 Stress Corrosion Cracking

Question 1

Stress corrosion cracking (SCC) requires which three factors to be simultaneously present?

Accepted Answer

Tensile stress, corrosive environment, and susceptible material

Answer

Heat, pressure, and dissolved oxygen

Answer

Compressive stress, high pH, and low temperature

Answer

Fatigue loading, hydrogen gas, and alkaline conditions

Question 2

Polythionic acid SCC (PTASCC) in refineries affects which material during which condition?

Accepted Answer

Sensitized austenitic stainless steels during shutdowns in sulfur service

Answer

Carbon steel exposed to caustic during normal operation

Answer

Duplex stainless steel in seawater during operation

Answer

Nickel alloys at high operating temperature

Question 3

Caustic stress corrosion cracking of carbon steel is historically known by what other name?

Accepted Answer

Caustic embrittlement

Answer

Hydrogen embrittlement

Answer

Wet H2S cracking

Answer

Amine SCC

Question 4

What post-weld treatment is most commonly applied to prevent stress corrosion cracking?

Accepted Answer

Stress relief post-weld heat treatment (PWHT)

Answer

Solution annealing at 2000°F

Answer

Normalizing

Answer

Water quenching after welding

Question 5

Liquid metal embrittlement (LME) can occur when carbon steel or other metals contact which substances?

Accepted Answer

Liquid mercury or molten zinc

Answer

Dilute hydrochloric acid

Answer

Concentrated sodium hydroxide

Answer

Hydrogen sulfide gas

Question 6

Amine stress corrosion cracking in carbon steel is best prevented by which measure?

Accepted Answer

PWHT of all carbon steel welds in amine service

Answer

Increasing amine concentration to reduce corrosivity

Answer

Reducing operating temperature below 100°F

Answer

Using plastic or FRP pipe liners