A bell-shaped metallic tube mounted above the exhaust nozzle and below the smokestack inside a steam locomotive's smokebox. It acts as an ejector throat, directing exhaust steam up the stack while drawing combustion gases evenly through the boiler flues. Adjusting its height is critical for maintaining an even draft across the firebed.
Heard on the job
The shop needs to lower the petticoat pipe an inch to get a better draft on the lower flues.
Related terms
Steam locomotive
A railway locomotive powered by the expansion of steam in cylinders.
Firebox
The combustion chamber of a steam locomotive where fuel is burned to heat water.
Blastpipe
An exhaust nozzle inside a steam locomotive smokebox that directs spent steam up the stack to draw air through the fire.