... and workers 4.supplying spare part 1.The pipe changed to a single return trip from the ... , preventing the lower drum drum package.3.Threaded pipe used to obtain the heat transfer enhancement effect, ... boiler adopts arched tube plate, two-wing flue pipe etc, thread, solve the smoke pot shell boiler ... is low, the coal output, adaptability, etc. high efficiency natural gas/oil steam boiler 4 tons capacity