Pipe thickness calculation!

Pipe Thickness determination!
A pipe is looked upon as a simple thin walled cylinder case in many instances, ie. The wall thickness consideration is negligible compared to the pipe diameter, and the diameter determination is reasonably accurate due to the negligible thickness assumption. It follows the basic analysis and calculations we often encounter in our basic training in the under graduate school. The pressure inside the pipe or its designed pressure (P) is first taken into account. say 10 Newtons/mm2. Then, the pipe diameter (D) is determined, based on consideration of pressure drops, and/or fluid flow expected. Assuming the diameter has been determined as 100 mm, a crossed sectional area can be calculated; the crossed-sectional area is then multiplied with the pressure, indicating the separating force inside the pipe. Remember that the same pressure at a particular point acts in all directions; it is a basic principle in fluid mechanics. Knowing your kind of pipe material, will give you the allowable theoretical pipe stress (S) in Newtons/mm2. The thickness (T) of the pipe will then be calculated using the formula below:

T= PD / 2S ; where T= mm ;P=Newton/mm2 ; D=mm; S= Newton/mm2

The theoretical computation is then compared to the nearest thickness available in the market, considering, possible pipe erosion and corrosion rate allowances per year, and desired operating life. Economic considerations, such as interest rate, pipe price escalation factor, and first cost of pipes are then taken into consideration, as well as the pipe supports costs, downtime cost consideration and affordability. In cases of special fluids being handled, the result of the thickness calculation is also referred to existing professional codes or building regulations adopted by local authorities or professional associations.
Written by: Sanoy Suerte, RME/MBM; Http://businessmanage.sosblog.com; Http://www.linkedin.com/in/sannysuerte