| 摘要 |
To make stress corrosion cracking caused by precipitation of a beta layer (Mg2Al3) in a welding part (5) or in the periphery of the welding part (5) hard to occur. An apparatus body (1) and a header (3) formed of an aluminum alloy with precipitation of magnesium suppressed by standardized heat treatment are assembled and welded, and natural gas containing mercury is subjected to heat exchanging. There are provided with backing metal (4) disposed on the back of the inner wall surface of one header (3) prior to standardized heat treatment and placed in contact with the other apparatus body (1) at the time of assembling and welding, a welding part (5) formed by being assembled and welded using first welding metal containing magnesium at percent content not less than 2.0% in a space part formed by the backing metal (4), the apparatus body (1) and the header (3), and a seal part (6) formed by seal-welding, so that first welding metal may not contact with fluid from a contact part between the backing metal (4) and the apparatus body (1), the contact part using second welding metal containing magnesium at percent content not more than 2.0%. |
