boiler scale

A less obvious advantage was that of boiler scale.

This build-up is known as boiler scale.

"Brand my boiler scale, that's plumb wonderful, Tom!"

Untreated, this builds up boiler scale on the tubes and particularly deposits sludge in the lower parts of the boiler.

On the other hand the formation of scale in the boiler was delayed because a proportion of the boiler scale constituents had already been left behind in the tender.

These compounds precipitated in due course as sludge and boiler scale, which could lead to blockages of the tubes, prevent the transfer of heat in the boiler and thus lead to risks in operating the engine.