Various Parts Of A Pressure Vessel: A Comprehensive Guide

Various Parts Of A Pressure Vessel

One of the most important pieces of stationary equipment at any process plant is pressure vessels. These pieces of pressure equipment are found in just about every petrochemical, refinery or chemical plant. Available in both vertical and horizontal variants, pressure vessels are used to house major chemical processes. Pressure vessels can carry or process fluids under various pressure and temperature ranges. 

Most pressure vessels are designed in accordance with AS 4343 – this is the Australian standard designed to regulate the construction and design of any boiler and pressure vessel. 

To ensure that they effectively and reliably serve their purpose, pressure vessels are designed with a variety of important parts. Read on below for a comprehensive guide on the different parts of pressure vessels. 

What Are Pressure Vessels?

A pressure vessel can be defined as a specially designed container for holding fluids under high pressure. In general, there are different types of pressure vessels, including cylindrical pressure vessels (vertical or horizontal) and spherical pressure vessels.  

Parts Of A Pressure Vessel 

Here’s a breakdown of the main parts of a pressure vessel: 


Normally conical, cylindrical or spherical in shape, a pressure vessel shell is made of different plates welded to another and so forth, to form a structure with a common rotational axis. 

Depending on the intended application of the pressure vessel, the shell can be made using a variety of metals, including carbon steel. This material ensures maximum strength at minimal wall thickness. The wall thickness affects the level of internal pressurisation that can be handled by the resulting vessel.   


Designed to be dished, spherical or semi-elliptical, the heads act as enclosures to the ends of a pressure vessel. Most pressure vessels use curved heads for a number of reasons. In addition to being stronger, curved heads are also less expensive, thinner and lighter than their flat counterparts. 


Designed to penetrate the shell or head of a pressure vessel, a nozzle is a cylindrical component. These components have a number of uses, including providing direct attachment to other equipment like heat exchangers, attaching instrument connections like pressure gauges, piping for guiding the flow of fluids into and out of the vessel and providing access to the vessel at a manway.  

Base Plate 

Part of the pressure vessel support, the base plate is considered to be among the non-pressurised parts of these vessels. The base plate is a flat metal ring that rests on a concrete foundation and is welded to the vessel’s support skirt, at the bottom. To secure the vessel to the concrete foundation, the base plate comes with holes around the perimeter of the circular ring that is designed to be placed over anchor bolts. 


Also considered to be the main part of a pressure vessel’s support, the skirt can be defined as cylindrical-shaped support for vertical pressure vessels. The upper end is welded to the bottom head of a vertical vessel, while the lower end is attached to the base plate – allowing the vessel to rest on the foundation.  

Final Thoughts 

Pressure vessels are designed to hold fluids, including compressed air, at high pressures and in some cases high temperatures. To efficiently serve their purpose, these structures are designed with a variety of essential components, in accordance with Australian Standards. Different metal pressure vessels have different properties and are therefore used in different applications. 

Register Your Pressure Vessel Design With Sherwood Engineering

Are you a mechanical engineer looking to register your pressure vessel? Sherwood Design & Engineering can help you ensure that your vessel design is compliant with the relevant safety standard, and meets the requirements for safety. 

Give us a call at (02) 9437 3566 or leave an enquiry if you would like to learn more about our pressure vessel engineering design and support services.