Part 6 - The basics of Shell and Tube Heat Exchanger

It is important at this point to understand the calculation of Maximum allowable Working Pressure is using thickness at corroded condition.

This post is a continuation of Part 5, so make sure you have understood Part 5 before diving in Part 6. But.. its OK if you want to look around though.

• Understanding Maximum Allowable Working Pressure (MAWP)

• A dive into MAWP Calculation.

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TODAY'S PERSPECTIVE

Understanding Maximum Allowable Working Pressure (MAWP)

• MAWP depicts the highest pressure that a pressure vessel or a heat exchanger can safely operate at its Design Temperature.

• Usually for a carbon steel material such as SA516 Gr 65N, Corrossion allowance up to 3mm is added on top of t_MAWP to account for corrossion over the lifetime of the equipment.

• t_MAWP Is also refferred to thickness at corroded condition.

• When calculating MAWP, it is assumed that the vessel is already in a corroded condition. So, as long as the thickness of the vessel is within the corrossion allowance, the MAWP does not change.

• What happen if the thickness reduction surpasses the corrossion allowance? The vessel will need to be derated or repaired to ensure safety.

A dive into MAWP calculation

• In Part 5 we went a bit on Calculating Shell Minimum Thickness and we stopped at Tselected.

Now lets calculate P_MAWP [use T_MAWP]

Refer Part 5 for the details

P_MAWP = SEt / [(r_s+C) + 0.6t)]

ID = 1140, r_s = 1140/2 = 570 (mm)

C = 3 (mm)

S = 148MPa, E=1

P_MAWP = 4.24Mpa

Maximum Allowable Working Pressure is calculated to be 4.24Mpa.

That's all!

We'll see you again on Wednesday. Thoughts, feedback and questions are much appreciated - respond here

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