Method for producing piping and method for forming oxide film on inner surface of copper pipe

1. A method of manufacturing a pipe, the method comprising:

an oxide film formation step of forming a copper oxide film on an inner surface of a copper pipe through injecting a chloride ion-containing aqueous solution into the copper pipe to fill the copper pipe,

wherein the chloride ion-containing aqueous solution is injected into the copper pipe according to a process that reduces interference on the formation of the copper oxide film from a shearing force applied to the inner surface of the copper pipe due to a flow of the chloride ion-containing aqueous solution through the copper pipe, wherein

a content of chloride ions in the chloride ion-containing aqueous solution is not less than 50 mg/L and not more than 300 mg/L.

2. The method of claim 1 , wherein

in the oxide film formation step, the chloride ion-containing aqueous solution is allowed to continuously flow through the copper pipe.

3. The method of claim 1 , wherein

in the oxide film formation step, injection of the chloride ion-containing aqueous solution into the copper pipe, keeping of the copper pipe stationary with the chloride ion-containing aqueous solution injected therein, and discharge of the chloride ion-containing aqueous solution from the copper pipe are sequentially performed.

4. The method of claim 1 , further comprising:

a pretreatment step of removing a surface deposit from the inner surface of the copper pipe through injecting an acid aqueous solution into the copper pipe to fill the copper pipe, the pretreatment step being performed before the oxide film formation step.

5. The method of claim 4 , wherein

the acid aqueous solution contains diluted hydrochloric acid.

6. The method of claim 1 , wherein

in the oxide film formation step, oxygen is dissolved in the chloride ion-containing aqueous solution before the injection into the copper pipe.

7. The method of claim 6 , wherein

a dissolved oxygen concentration of the chloride ion-containing aqueous solution is not less than 5 mg/L.

8. The method of claim 6 , wherein

oxygen is dissolved in the chloride ion-containing aqueous solution by bubbling of the chloride ion-containing aqueous solution with air or oxygen.

9. The method of claim 6 , wherein

oxygen is dissolved in the chloride ion-containing aqueous solution by stirring the chloride ion-containing aqueous solution.

10. The method of claim 1 , wherein

the chloride ion-containing aqueous solution contains an aqueous sodium chloride solution.

11. The method of claim 1 , wherein

a pH of the chloride ion-containing aqueous solution is not less than 5.8 and not more than 8.6.

12. A method of forming an oxide film on an inner surface of a copper pipe through injecting a chloride ion-containing aqueous solution into the copper pipe to fill the copper pipe, thereby forming a copper oxide film on the inner surface of the copper pipe,

wherein the chloride ion-containing aqueous solution is injected into the copper pipe according to a process that reduces interference on the formation of the copper oxide film from a shearing force applied to the inner surface of the copper pipe due to a flow of the chloride ion-containing aqueous solution through the copper pipe, wherein

a content of chloride ions in the chloride ion-containing aqueous solution is not less than 50 mg/L and not more than 300 mg/L.

13. A method of manufacturing a pipe, the method comprising:

an oxide film formation step of forming a copper oxide film on an inner surface of a copper pipe through injecting a chloride ion-containing aqueous solution in which a content of chloride ions is not less than 50 mg/L and not more than 300 mg/L into the copper pipe to fill the copper pipe.

14. A method of forming an oxide film on an inner surface of a copper pipe through injecting a chloride ion-containing aqueous solution in which a content of chloride ions is not less than 50 mg/L and not more than 300 mg/L into the copper pipe to fill the copper pipe, thereby forming a copper oxide film on the inner surface of the copper pipe.