Design Of Simple Pressure Vessels

Introduction To Pressure Vessel

Example of pressure vessel
Fig. Example of Pressure Vessels 

What is Pressure Vessels Or Tank ?

Pressure Vessels are used to store the fluid e.g. Air, Water,
steam under the pressure. For some project design of pressure
vessel is very important because  of safety , avoid
bursting. Day to day life you might have seen many types of
tanks. This all tanks are designed on the basis of Internal
fluid  pressure required. So, main design criteria is
Internal Pressure. There are some other conditions which
could affect on design like External pressure, any extra
outlets ,gauges ,type of weld joints and type of material

Design Tips For Pressure Vessel Or Tank.

1) Decide the Problem :

Firstly, decide the Internal pressure of air required for
your project in bar or psi. If total storage volume is known
or required then decide the value of volume, On volume the
total length of vessel is depended. 

2) Types Of Pressure vessel

Pressure Vessels are mainly classified in two types thick and
thin cylinder. Designing Pressure Vessels means you have to
find the thickness of the pressure vessel. Generally thin
tanks are preferred for storage of air.

3) Pressure Vessel Construction and Parts

Shell : A Shell is
cylindrical in shape and have dimensions according to
internal pressure and total volume of air that need to be
stored. Shell thickness is found out by using thickness

Pressure vessel Shell and end closure
fig. Pressure vessel Shell and end closure

End Closures : 
Pressure Vessel also classified as Open type or Close type. End
Closures are used at the end of shell to close the both ends of
shell. Types of pressure vessel’s end closures are-
Hemisperical head, Semi-ellipsoidal head, torisherical head,
Conical head or plate type head .
Mostly used head is
Hemisperical head and plate type.

Types of end closures and supports
Fig. Types of end closures and supports

Welding Method :

Shell and End Closures are welded by using Single lap weld.
According to welding joint the weld joint efficiency is


Pressure vessels are mounted either vertically or
Horizontally by using supports. Supports are those which hold
the pressure vessel on the floor and takes external load
acting on tank  such as wind load, Bending load and
seismic load. For Horizontal Pressure- Saddle support or
ring supports
are used.

For Vertical Pressure vessel -Lug Support, bracket
supports are used.

4) Material used for Pressure Vessel :

Alloy steel, plain Carbon steel these are commonly materials
used for vessel but you can find more specific stranded
material on ASME Website.

5) Stresses developed in vessel:

Failure of pressure vessel (vessel will burst) if ultimate
tensile stress of material is less that longitudinal stress
and Hoop stresses.

Failure Of Pressure Vessel
Fig. Failure Of Pressure Vessel

6) Opening To Pressure Vessel :
Opening is needed to fix the pressure gauges, Inlet Pipes and
outlet Pipes. Some nut bolts or flanges, gaskets are used to
attach the accessories to tank. Many pressure vessel has Safety
Valve for safety purpose.

Fig. Opening to Pressure Vessels and types of

Other Important things are:

  • Pressure Vessels should be designed for gauge or working
    pressure. The standard design procedure is not applicable for
    Absolute pressure.
  • Manufacturing of vessel must be done properly.
  • Small leakage could fail the pressure vessel.
  • Welding must be done correctly, Mostly Vessels fails at
    welding section only.
  • Handling of vessel should be proper so that it won’t
    damage by Impact Load.
  • Material should be selected on Cost and availability.

This articles was just introduction about vessel design, If
you need detail information about formulas or any other help
then you would refer machine design book by Bhandari. If you
have any query then ask in Comments..

Thank you !