Well Woodie, they would be handy for scale removal from the top of the crown sheet, and it is possible that the water in the area where the original customer was was full of minerals--so I guess that you get the prize.*
Scale was more of a problem for locos that always got the same water- local switchers, and the like. Road locos usually suffered less from this problem, because the varying amounts and types of minerals, and the amount of acidity in the water tended to cause the scale to fracture and fall off the firebox sheets. All that debris ended up on the mud ring between the bottom sheets of the firebox, and outer shell. Periodically, this had to be raked, and washed out through pipe plugs located in the area.
*one of the stogies that Gromit has chewed on.
____________________ Fix it again, Mr Gates--it still works!"