Highly corrosion-resistant copper tube

Abstract

Use of a heat transfer tube in a damp environment in air-conditioning equipment and exposed to corrosive action caused by a corrosive medium comprising at least one lower carboxylic acid, the heat transfer tube a copper tube comprising 0.10-1.0% by weight of P and the balance consisting of Cu and inevitable impurities. The corrosive action progresses in the form of an ants' nest from an outer surface of the heat transfer tube in a direction of its wall thickness, wherein. Also, use of a copper tube comprising 0.10-1.0% by weight of P and the balance consisting of Cu and inevitable impurities for improving corrosion-resistance against ant nest corrosion caused by a corrosive medium consisting of a lower carboxylic acid in a damp environment, method of inhibiting ants' nest corrosion in a heat transfer tube, and a method of positioning a tube in an air conditioning apparatus or a refrigeration apparatus.

Description

CROSS REFERENCE TO RELATED APPLICATION[0001]This application is a divisional of U.S. application Ser. No. 14 / 849,955 filed on Sep. 10, 2015 (the benefit of which is claimed in this application), which is a continuation of the International Application No. PCT / JP2014 / 052418 filed on Feb. 3, 2014 (the benefit of which is claimed in this application), which claims the benefit under 35 U.S.C. § 119(a)-(d) of Japanese Application No. 2013-055963 filed on Mar. 19, 2013 (the benefit of which is claimed in this application), the entireties of which are incorporated herein by reference.BACKGROUND OF THE INVENTIONField of the Invention[0002]The present invention relates to a highly corrosion-resistant copper tube, and more particularly relates to a copper tube suitably usable as a heat transfer tube and a refrigerant tube in air-conditioning equipment and refrigerating equipment, for example.Description of Related Art[0003]A tube made of a phosphorous deoxidized copper (JIS-H3300-C1220T) havi...

AI Technical Summary

Benefits of technology

The present invention provides a copper tube with improved resistance against ant nest corrosion, which is commonly found in damp environments such as air-conditioning and refrigerating equipment. By increasing the P content of the copper tube, its resistance against ant nest corrosion is significantly improved compared to conventional copper tubes. This results in a longer service life for the equipment using the copper tube. The method for improving the corrosion resistance of the copper tube involves forming it with a material containing 0.10-1.0% by weight of P and the balance consisting of Cu and inevitable impurities. The practical copper tube provided by the present invention is superior to conventional copper tubes in terms of its anti-corrosion property.

Problems solved by technology

However, it is recognized that the above-described phosphorous deoxidized copper tube used in the air-conditioning equipment and the refrigerating equipment suffers from generation of so-called “ant nest corrosion” (or “formicary corrosion”) which is an unusual corrosion that progresses in the form of an ants' nest from the surface of the tube in a direction of its wall thickness.

It is known that generation of the ant nest corrosion is particularly remarkable where the phosphorous deoxidized copper tube is used as a conduit in the air-conditioning equipment and the refrigerating equipment, which conduit is liable to dewing.

Once the ant nest corrosion is generated, it progresses rapidly and penetrates through the wall of the copper tube in a short time, giving rise to a problem that the equipment becomes unworkable.

However, the copper tube obtained by reducing the P content has not yet achieved a sufficiently high resistance against the ant nest corrosion which is comparable to that of the oxygen-free copper tube.

Images