Metric and Imperial Units

The above formulas may be used with both imperial and metric units. As with all calculations care must be taken to keep consistent units throughout with examples of units which should be adopted listed below:

Notation

• σ_H = hoop stress, psi or MPa
• D = outer diameter, in or mm
• E = modulus of elasticity, psi or MPa
• P = pressure under consideration, psi or MPa
• P_i = internal pressure, psi or MPa
• P_o = external pressure, psi or MPa
• r = radius to point of of interest, in or mm
• r_i = internal radius, in or mm
• r_o = external radius, in or mm
• t = wall thickness, in or mm
• ∆_P = change in pressure, psi or MPa

1. D. Roylance. Pressure Vessels. Cambridge, MA. 2001. Publised article.
2. D.C. Nnadi, C.C. Eze, J.C. Aririguzo, C.S. Agu. Effect of Stresses on the Walls of a Pressure Vessel. Okpara University, Umudike, Nigeria. 2017. Published in "International Journal of Engineering Trends and Technology (IJETT)".
3. The University of Puerto Rico, Mayagüez Campus (UPRM). (n.d.). Spherical pressure vessels [PDF file]. Retrieved from http://academic.uprm.edu/pcaceres/Courses/MMII/IMoM-6A.pdf