Thick Wall Pressure Vessels - Brain Waves.avi

Summary

This video explains the differences between thick-walled and thin-walled pressure vessels. It introduces key concepts, emphasizing that thin-walled vessels, like soda cans, have a wall thickness significantly smaller than their mean diameter, while thick-walled vessels, such as hydraulic cylinders, have comparable thickness. The speaker discusses the three types of stress present in these vessels: axial, radial, and hoop stress. Notably, axial stress remains constant through the thickness, while radial and hoop stresses vary. An example illustrates stress calculations, highlighting that thick-walled vessels behave differently due to stress variation across the wall, providing essential insights into pressure vessel design.

Takeaways

• 😀 Thin-walled pressure vessels have wall thickness significantly smaller than the mean diameter, typically when the ratio of mean diameter to thickness is greater than or equal to 20.
• 😀 An example of a thin-walled pressure vessel is a soda can, which has thin walls compared to its diameter and is under internal pressure.
• 😀 Thick-walled pressure vessels have a wall thickness comparable to the mean diameter and are subjected to varying stress throughout their thickness.
• 😀 Hydraulic cylinders and deep-sea submersibles are common examples of thick-walled pressure vessels.
• 😀 Stress distribution in thin-walled vessels is constant across the thickness, simplifying calculations for engineers.
• 😀 In thick-walled pressure vessels, axial, hoop, and radial stresses are calculated separately due to their variation with radius.
• 😀 Axial stress remains constant throughout the thickness of the thick-walled pressure vessel.
• 😀 Hoop stress varies with radius and is significantly influenced by internal pressure.
• 😀 Radial stress at the inner wall equals the internal pressure, while the radial stress at the outer wall is influenced by external pressure.
• 😀 Understanding the differences between thin-walled and thick-walled pressure vessels is crucial for safe and effective design in engineering applications.

Q & A

What is the main difference between thin-walled and thick-walled pressure vessels?

The main difference lies in the ratio of the mean diameter to the wall thickness. A pressure vessel is considered thin-walled if the mean diameter (D_subm) is at least 20 times the wall thickness (T). In contrast, thick-walled pressure vessels have a smaller ratio.

Can you provide an example of a thin-walled pressure vessel?

A common example of a thin-walled pressure vessel is a soda can. Its wall thickness is significantly smaller than its diameter, allowing it to withstand internal pressure.

What happens when a thin-walled pressure vessel is not pressurized?

When a thin-walled pressure vessel, like a soda can, is not pressurized, it becomes weak and can easily be deformed or ruptured.

What are some examples of thick-walled pressure vessels?

Examples of thick-walled pressure vessels include hydraulic cylinders and deep-sea submersibles, which are designed to withstand high external pressures.

What is meant by 'mean diameter' in the context of pressure vessels?

The mean diameter is defined as the average of the outer and inner diameters of the pressure vessel. It is used to determine the pressure vessel's classification as thin-walled or thick-walled.

What stress types are considered in thick-walled pressure vessels?

In thick-walled pressure vessels, there are three types of stresses to consider: axial stress, radial stress, and hoop (or circumferential) stress.

How do stresses behave in thick-walled pressure vessels compared to thin-walled ones?

In thick-walled pressure vessels, stresses in the radial and hoop directions vary through the thickness of the wall, whereas in thin-walled vessels, the stress is assumed to be constant throughout the thickness.

What relationship does radial stress have with internal and external pressures?

The radial stress at the inner wall of a thick-walled pressure vessel equals the internal pressure, while the radial stress at the outer wall equals the external pressure.

What is the formula for calculating hoop stress in thick-walled pressure vessels?

The formula for hoop stress involves variables like inner and outer radii, and internal and external pressures, and it typically varies depending on the location within the wall.

What are the implications of incorrect stress calculations in pressure vessels?

Incorrect stress calculations can lead to failure of the pressure vessel, resulting in leaks, ruptures, or catastrophic failures, which can be dangerous.