Boiler design book

There are many books available on the topic of boilers and boiler systems, covering a wide range of topics including:

Each individual boiler must be individually approved; class approval is not an option.
Any design change to an existing shell design must also be approved at extra cost to the manufacturer.
Even minor changes to a shell such as:

The most basic definition of a boiler is a closed vessel in which water is heated until the water has reached the desired pressure and temperature.
This definition is extremely broad and the project team will need to narrow down the specific type of boiler that will be required.