Abstract: A method for producing a boiling heat transfer pipe having in the circumferential wall thereof one or a number of helical or annular cavities under a ceiling wall containing a row of openings regularly spaced at predetermined intervals along the length of the cavities, such method partly including in an arbitrary order the steps of: (a) pressing a set of groove-rolling discs of gradually increased diameters against the outer surface of a blank pipe to form a fin around the circumference of the pipe; (b) pressing a notching gear against the outer side of the fin to cut notches in upper fin portions at predetermined intervals along the length of the fin; (c) pressing a set of splitting roller discs with splitting edges of gradually increased angles substantially along a center line on the outer side of the fin to split and spread apart the upper fin portions in the axial direction of the pipe; and (d) pressing a press roller centrally against the split upper fin portions to form flat side wings on lateral sides

Abstract: A heat transfer pipe including a cylindrical heat transfer pipe body and a plurality of circumferential or spiral fins integrally formed on the outer surface of the pipe body, the upper portion of each of the fins having one or more circumferential grooves to divide it circumferencially into at least two parts and a plurality of axially extending breaks to divide it axially into a number of parts. The fins further may have notches formed therein with a predetermined pitch in a direction crossing the fins to divide them into a plurality sections, and a plurality of discrete beads are integrally formed on the inner surface of the body along imaginary lines having a lead angle which is in reverse relation to the lead angle of the fins, the beads being formed on at least some of the intersections between the imaginary lines and the fins.