Part 4 - The basics of Shell and Tube Heat Exchanger

SA 516 Gr 70N is a popular steel grade. It is highly sort after for welded fabrication in industry pressure vessel and boilers. Here's what we're covering today:

• Understanding Ultimate Tensile Strength of SA 516 Gr 70N

• Yield Strength of SA 516 Gr 70N

• Allowable Stress of SA 516 Gr 70N

Let’s get to it! 👇

TODAY'S PERSPECTIVE

Understanding Ultimate Tensile Strength of SA 516 Gr 70N

• What Is It? Think of UTS as the maximum "pulling power" a material can withstand before breaking.

• Why It Matters: It helps us understand the upper limit of stress a material can endure before it breaks.

• SA 516 Gr 70N Example: Typically, this material has a UTS between 485 – 620 MPa (or 70,000 – 90,000 psi).

Understanding Yield Strength of SA 516 Gr 70N

• What Is It? This represents the stress level at which a material transitions from temporary (elastic) deformation to permanent (plastic) deformation.

• Why It Matters: It provides a threshold to ensure our designs remain intact and revert to their original shapes after stress removal.

• SA 516 Gr 70N Example: Its yield strength starts at around 260 MPa (or 38,000 psi).

Understanding Allowable Stress of SA 516 Gr 70N

• What Is It? This is the safe limit of stress that a material can handle in service, providing a buffer to account for uncertainties.

• Why It Matters: It offers a safety margin, ensuring the material's long-term reliability.

• Relation to ASME: The American Society of Mechanical Engineers (ASME) Section VIII provides guidelines on determining allowable stress. For many materials, this is derived from either 1/3.5 of the UTS or 2/3 of the yield strength (whichever is lesser) - 485MPa/3.5 or 260×2/3 [138.6MPa or 173.3 MPa]

• This means that allowable stress for SA 516 Gr 70N is 136.6MPa

I think we are quite ready to proceed with shell thickness calculation, what do you think?

That's all!

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