Basics of Pressure Vessels

What is Pressure Vessel ?

pressure vessel is a container designed to hold gases or liquids at a pressure substantially different from the ambient pressure.

Types of Pressure Vessels:

We will learn classification or types of pressure vessel according to their fabrication, function, material, geometry, pressure, heating methods, orientation, installation and wall thickness of pressure Vessels.

Classification or Types of Pressure Vessels:

  1. According to fabrication:

    1. Shop Fabricated Pressure Vessel.
    2. Field Fabricated Pressure Vessels.
    3. Riveted Pressure vessels.
    4. Welded Pressure Vessels.
    5. Forged Pressure Vessels.
    6. Cast Pressure Vessels.
    7. Multi-Layered Pressure Vessels.
  2. According to Functions:

    1. Reactor.
    2. Accumulator.
    3. Column.
    4. Drum.
  3. According to Material of Construction:

    1. Steel Vessel.
    2. Cast Iron Pressure Vessels.
    3. Aluminum Pressure Vessels.
  4. According to Pressure:

    1. Internal Pressure Vessels.
    2. External Pressure Vessels.
  5. According to Method of Heating:

    1. Fired Pressure Vessels.
    2. Unfired Pressure Vessels.
  6. According to Geometry of Vessels:

    1. Cylindrical Pressure Vessels.
    2. Spherical Pressure Vessels.
    3. Conical Pressure Vessels.
  7. According to Orientation of Pressure Vessels:

    1. Horizontal Pressure Vessels.
    2. Vertical Pressure Vessels.
    3. Inclined Pressure Vessels.
  8. According to Installation of Pressure Vessels:

    1. Fixed Pressure Vessel.
    2. Portable Pressure Vessels.
  9. According to Wall Thickness of Pressure Vessels:

    1. Thick Walled Pressure Vessels.
    2. Thin Walled Pressure Vessels.

so, this is the list of various types classification of available generally in Pressure vessels. Now we will see some common Vessels parts.

Vessels Parts:

In Pressure Vessel following are the general vessel parts:

  1. Vessel Body
    1. Cylindrical Shell
    2. Spherical Shell
  2. Vessel Heads
    1. Flat heads
    2. Tori spherical heads
    3. Elliptical heads
    4. Hemispherical heads
  3. Vessel Supports
    1. Leg supports
    2. Saddle Supports
    3. Lug Supports
    4. Skirt Supports
    5. Ring Supports
  4. Nozzles and Manholes
    1. Process Nozzles
    2. Inspection Nozzles
    3. Instruments Connections
    4. Pad Type Nozzles
    5. Sight/Light Glasses
    6. Vent Nozzles
    7. Drain Nozzles
    8. Cylindrical Manways
    9. Elliptical Manways
  5. Flanges
    1. Slip on Flanges
    2. Weld Neck Flanges
    3. Screwed Flanges
    4. Lap Joint Flanges
    5. Blind Flanges
    6. Socket Weld flanges
    7. Plate Flanges
    8. Reducing Flanges
    9. Pad Flanges
    10. Tongue and groove Flanges
  6. Gaskets
    1. Ring Type Gaskets
    2. Spiral Wound Gaskets
    3. Metal Jacketed Gaskets
    4. Elastomeric Gaskets
    5. Corrugated Gaskets
  7. Internals
    1. Trays
    2. Piping Distributors
    3. Baffles
    4. Demisters
    5. Packing
    6. Liquid Distributors
    7. Vortex breakers
    8. Bed Supports
    9. Coils

This all above are common vessels parts used pressure vessel fabrication.

Now will see Next Most Commonly used Code Book for Pressure Vessel.

ASME – American Society of Mechanical Engineers.

ASME BOILER AND PRESSURE VESSEL CODE

  •  SECTION I – POWER BOILERS.
  • SECTION II – MATERIALS.
  • SECTION III – NUCLEAR POWER PLANT COMPONENTS.
  • SECTION IV – HEATING BOILERS.
  • SECTION V – NONDESTRUCTIVE EXAMINATION.
  • SECTION VI – RECOMMENDED RULES FOR CARE AND OPERATION OF HEATING BOILERS.
  • SECTION VII – RECOMMENDED RULES FOR CARE OF  POWER BOILERS.
  • SECTION VIII – PRESSURE VESSELS ( DIV 1, DIV 2,  DIV 3 ).
  • SECTION IX – WELDING AND BRAZING QUALIFICATION.
  • SECTION X – FIBER GLASS REINFORCED PLASTIC PRESSURE VESSEL.
  • SECTION XI – RULES FOR IN-SERVICE INSPECTION OF NUCLEAR POWER PLANT COMPONENTS

Out of above ASME sections ASME SECTION VIII Code will be used for Pressure Vessels. in this sections there are three divisions. this code used in combination of Section II for materials, Section V for NDT Testing and Section IX for Welding and Brazing qualifications.

lets see short Summary of ASME SECTION VIII DIVISION 1, DIVISION 2 And DIVISION 3.

  1. ASME SECTION VIII DIVISION 1 – Unfired Pressure Vessels Rules.
  2. ASME SECTION VIII DIVISION 2 – Alternative Rules for Pressure Vessels.
  3. ASME SECTION VIII DIVISION 3 – Alternative Rules for High Pressure.
Commonly used Material for Construction of Pressure Vessels:

In fabrication of pressure vessel Steel,Cast iron and Aluminum material are used most commonly but out of this Steels are most widely used for pressure vessel fabrication so , from group of Steel Carbon steel , Alloy steel , Stainless steel are used.

Material Selection guideline for Pressure vessels:

While selecting the Material of construction of pressure vessels Temperature is most important factor to be considered. so, lets see some materials suitable for various types of Temperature Service.

  1. Low Temperature Service – Carbon steel, 3 1/2 Nickel, 2 1/2 Nicke.
  2. Intermediate Temperature Service – Carbon steel.
  3. High Temperature Service –  C-1/2 MO, 1 Cr-1/2 MO,2 1/4 Cr -1 MO, Stainless Steel, Incoloy, Inconel.
  4. Cryogenic Service – Stainless steel, 9 Nickel.

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