Utility and industrial boilers commonly use multi-stage centrifugal pumps; however, other types are used.

Going with stainless steel or a "double boiler" using heat resistant ceramic or glass is safer.

Later boilers used a more rounded section, despite the difficulty of inserting and sealing the tube ends when they were no longer perpendicular.

I explained how a boiler uses fuel to start a fire to heat water and force steam through the pipes to warm the house.

Many coal-fired boilers used multiple firedoors and teams of stokers, often from both ends.

Later boilers used a more rounded section, although still asymmetrical rather than fully cylindrical.

Later boilers could use the wider plates then available and used two hoops, so as to reduce the number of riveted joints.

Some boilers use vertical rod stays between the firebox crown and top of the boiler shell.

There's a sort of well where the boiler used to be.

However, some industrial boilers still use it and so do a few old buildings, including in New York City.