From a variety of vessels, the most commonly type of vessels which are classified mostly based on their geometry and use are as follows.
- Storage Tank
Chemical and petrochemical industries require variety of operating liquids and gases to be stored for processing and final storage before transportation this requirement is fulfilled through the use of storage tanks. Storage tanks are of mainly designed using codes of API (American Petroleum Institute).
API 650 – Design of welded tanks
This scope of this code gives the minimum requirements for design, fabrication, erection and testing of flat bottom, cylindrical, closed and open top welded storage tank for atmospheric pressure. Higher internal pressure is permitted up to 2.5 psig.
API 620 – Design and construction of large, welded, low pressure storage tank
This scope of this code gives the requirements for design and construction of flat bottom, cylindrical and spherical, closed welded storage tank for low pressure. Internal pressure for this code is limited to 15 psig.
Carbon steel is preferably used for construction of storage tanks.
- Vertical oriented vessels with formed ends
This type of vessel is preferred where the internal design pressures are higher and require a stronger design. Vertical vessels are usually supported by legs, lugs and skirt support.
Short and medium sized vertical vessels are leg supported. Legs are usually structural sections like I, C or equal angles.
Short vessels supported on beams use lug support.
Tall towers used are distillation, separation or absorption are supported by a structural skirt. Skirt is a cylindrical or conical (flared) shell supporting the entire vessel from its bottom. The skirt is considered along with a base plate, top ring, supporting gussets and bolts while designing it for structural stability.
Pressure vessel is designed, fabricated and inspected using the specified code e.g. ASME Section VIII Div 1 requirements. Vessel supports are designed using appropriate strength calculation theories.
Material selection depends on the process requirements and corrosion allowances.
- Horizontal oriented vessel with formed ends
Horizontal vessels are designed depending on the process specifications using specified codes. The horizontal orientation of vessel requires a saddle support. Saddle support is designed on the basis of Zick analysis or the ASME Section VIII Div 2 code requirements.
Pressure vessel is designed, fabricated and inspected using the specified code e.g. ASME Section VIII Div 1 requirements.
Material selection depends on the process requirements and corrosion allowances.
Pressure Vessel guide 