Polypropylene and polyolefin pellets are gravity fed through a snap cooling brass mandrel, reheater, blown into a large bubble using air pressure and temperature, and collapsed at the base of the four-storey chamber into a flat sheet by convergence rollers, and the sheet is then slit.
12.
As weight and power and length increased, there were experiments with flexible boiler casings; from 1910 the Santa Fe road introduced 2-6-6-2 locomotives weighing, with a long boiler barrel, with a firetube reheater and a firetube feedwater section in front, each separated by a blank section, and variants of a telescopic or bellows type boiler casing.
