This document discusses thin and thick cylinders. Thin cylinders have a wall thickness less than 1/15 to 1/20 of the diameter and are used to contain fluids under pressure. Thick cylinders have a wall thickness over 1/20 the diameter and are used in industries like chemical and petroleum that require withstanding high pressures and temperatures. The document outlines the stresses thin cylinders experience, including circumferential hoop stress along the circumference and longitudinal stress along the length, and provides formulas to calculate each stress. It also briefly mentions thick spherical shells and thick cylinders.

1. UNIT-II
Thin, Thick cylinders

2. Thin cylinders
• Thin cylindrical shell and spherical shell are used to contain
fluids or gas under pressure(Tanks, Boilers, Pump cylinders,
Pipes, Compressed air receivers)
• When the ratio of wall thickness to the diameter of the
cylinder is less than 1/15 to 1/20, it is called thin cylinder.

3. • A cylinder with a wall thickness of more than 1/20 of its inner diameter.
• Thick walled cylinders are widely used in chemical, petroleum, military
industries as well as in nuclear power plants. They are usually subjected
to high pressure & temperatures which may be constant or cyclic.
Thick cylinders

4. Stresses in thin cylinders
• When the pressure inside the cylinder is developed, the cylinder walls
are subjected to tensile stresses.
• Based on its direction in which they are acting,
1. Circumferential stress or Hoop stress – Stress acting along the
circumference of the cylinder(σc or σ1). Split in to two semi circular
halves
2. Longitudinal stress – Stress acting along the length of the cylinder(σl or
σ2). Split in to two cylinders

5. Circumferential stress or Hoop stress
d – Internal dia of cylinder
t – wall thickness
p – Internal fluid pressure
L – length of the cylinder

7. Longitudinal stress

10. Thin spherical shell

12. Thick cylinders

14. Important formulas – Thick cylinder