Helical groove heat exchange pipe for water heater

This invention relates to one spiral tank exchange tube, which is applied to inside tube heat exchanging with screw inner rib with flow Re lower than 7000 area with at least one part of tube section inner wall surface at entrance of flow nearby inner surface with several protruding parts with height for 0.5mm to 1.5mm; the height of protruding part height H1 and inner radium proportion as 0.05 to 0.15 or with protruding part height H1 and spiral rib height Hm proportion as 1 to 3.