To help understand what needs to be done and why things need to be done in a certain way, the following procedure presumes that the boiler is completely cold and dry, such as after a prolonged shutdown or annual inspection.
Steps can be omitted for boilers with some residual heat still in them and a typical example of this could be the start up after a weekend shutdown where the boiler has dropped in pressure and cooled, yet still has heat in it.
Note: The need to heat the boiler slowly will be explained throughout this procedure and it can take many hours for a large cold boiler to be heated correctly to operating temperature and pressure. Timing will also depend on how much treated water is available to fill the boiler, so be prepared for a long day and you may have to include a shift handover procedure to safely complete the task.