# Material Selection for Oil and Gas Material 3

Question 8

Select a list of materials to fabricate a 2 m diameter by 4 m tall pressure vessel to be used in a processing stream in the Syncrude plant. The operating parameters are such that the environment is acidic, pH=4, there is a presence of oxygen and the tank contains a brine comprised of sulphate ions and bicarbonate ions. It operates under constant pressure and at a temperature of 45oC.

Solution

For this question, safety criteria for this very critical because of the high human risk involved.  The following conditions should be used:

εf  0.20

KIC ≥ 120 MPa√m

Constant well pressure of 2500 kPa

Constant temperature of 45oC

Thickness of pressure vessel is 2.5cm.

Diameter of vessel is 50 cm

Hoop Stress

We must calculate the hoop stress to get a better understanding of the internal pressure.  We used the following to calculate this:

For the considerations, we have stated the primary, secondary, and other considerations:

Industry Standards

Through research, we have found that most pressure vessels built today use AISI 304 AND AISI 316 Steels. Another used for larger diameter and thinner walls is AISI 4130.

Some of the data could not be located, therefore, we were not able to fully complete the table.  However, for Corrosion resistance, SCC and Weldability, we used a grading system to easier create our CCR.

Materials Properties Table:

From the CCR, we can see that AISI 410 T&Q230 is the best choice of material, but because the εf < 0.20, it must be struck from the list.  Therefore, second in line is AISI 410 Q&T650.  This is the best choice overall, given that our εf meets required specs.  We take a look at the above table to ...