Pressure Vessel Steels

Question 1

Which steels are used for the pressure vessel?

Answer 1

Ferritic low alloy steels in quenched tempered form with bainitic microstructure and very fine grain size

Question 2

What the effects of the elements in low alloy steels?

Answer 2

Carbon - level of mild steel for strength
Mn and Mo - for extra strength
Ni - correct level of hardenability, decrease DBTT
S P - can lead to intergranular embrittlement

Question 3

Why is the pressure vessel forged?

Answer 3

Large forging remove the number of welds
Welds can be removed from high flux areas
Fewer welds mean fewer potential flaws and necessary inspections

Question 4

What are two types of pressure vessels?

Answer 4

AP1000 and EPR

Question 5

What are the main stages of the process?

Answer 5

Ingot -> upset forged -> enlarged, squared and drawn

Question 6

What post forging heat treatments are used?

Answer 6

Austenising, quench, annealing, air cool