Press-chem tubes were part of the system that Cloud City used to mine Tibanna from Bespin's atmosphere. Tibanna gas was drawn from the atmosphere into the heavily pressured tubes[1] where it was stabilized[2] and then moved to the city's refineries.[1]
Sources
- Galaxy Guide 2: Yavin and Bespin
- Galaxy Guide 2: Yavin and Bespin, Second Edition
- The Essential Guide to Weapons and Technology