| 摘要 |
PROBLEM TO BE SOLVED: To provide a heat transfer pipe or a header pipe for ORV in which cracking or peeling is hard to occur on a sacrificial anode layer even in an operation environment of the ORV.SOLUTION: A heat transfer pipe 2 or header pipes 3 and 4 for an open rack type vaporizer include a base material 21 made from an aluminum alloy and a sacrificial anode layer 22 which has a thickness of at least 100 μm and is made from an aluminum alloy put on at least a part of the outside surface of the base material 21. The sacrificial anode layer 22 has a lamination structure in which a plurality of thermal spray coats 22a are stacked. In a cross section in a thickness direction of the sacrificial anode layer 22, an average film thickness of the thermal spray coats 22a is in the range of 3-8 μm in a region from an interface with the base material 21 to at least a depth of 100 μm. A degree of circularity of granular system, which is calculated by a following formula in the granular system formed in such a state as sandwiched in the lamination structure, takes a value of 0.5 or more and represents a pseudo circle. A quantity density of rough grains 23 whose average diameter is 20 μm or larger is less than 2.5 pieces/mm. Circularity = 4&pgr;×area/(peripheral length). |
