The story
From blast (“forcible stream of gas, etc., from an orifice; exhaust steam from an engine”) + pipe.
Etymology from Wiktionary, CC BY-SA 4.0.
blastpipe
blast·pipeToday it means: A pipe forming part of the exhaust system of a steam locomotive that discharges exhaust steam from the cylinders up into the smokebox beneath the chimney in order to increase the draught through the firebox; this speeds up the release of smoke through the chimney. Full definition →