JPH01316431A - Corrosion-resistant copper alloy pipe for piping of refrigerant - Google Patents

Abstract

PURPOSE:To obtain the title copper alloy pipe in which peculiar honeycomb corrosion is hard to occur under each condition of dewing, temp. and ventilation particular to piping for a refrigerant by specifying the content of Sn, etc. CONSTITUTION:The above copper alloy pipe contg., by weight, 0.01-3.0% Sn and 0.015-5.0% total of one or more kinds among Fe, Al, Ni and Mn and the balance copper with ordinary impurities is prepd. It required, one or more kinds among <=0.5% P, <=0.1% Mg, <=0.2% Si and <=1.0% Zn are furthermore added thereto. As for the content of oxygen, >=100ppm is preferably regulated in either case of the above compsn. By such constitution, in the pipe, excellent corrosion resistance is shown even if water drops caused by dewing, etc., are stuck to the surface and used under the conditions of peculiar temp. and ventilation, and its service life as a piping material for a refrigerant can be increased.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a copper alloy tube for refrigerant piping, and particularly to a copper alloy tube with improved corrosion resistance against moth-web pitting corrosion.

[Conventional technology]

In general, deoxidized steel pipes are widely used for refrigerant piping because they have good corrosion resistance, bending workability, and brazing properties.

[Problem to be solved by the invention]

However, the surface of these pipes is cooled by the refrigerant flowing inside, causing water vapor in the atmosphere to condense on the surface, or
If water droplets adhere to the surface of the pipe for some other reason, and due to the unique temperature and ventilation conditions formed by the structure of the condenser, evaporator, compressor, insulation material, etc., a battery effect may occur, causing localized damage from the outside surface of the pipe. It may cause peculiar corrosion in the form of an ant nest. In addition, this corrosion grows rapidly, causing leakage in a short period of time and causing equipment to lose its functionality.Cupper alloys, which have better resistance to this kind of ant nest pitting corrosion than conventional phosphorus-deoxidized copper, Development of tubes is strongly desired.

[Means to solve problems]

The present invention was developed as a result of intensive studies in view of the above points, and its purpose is to solve situations where water droplets adhere to the surface due to dew condensation, etc., and where unique temperature and ventilation conditions are created. The purpose of the present invention is to provide a copper alloy pipe for refrigerant piping, which is more prone to corrosion than conventional phosphorus-deoxidized steel pipes, even when used in refrigerant piping.

That is, in the invention of claim 1 of the present invention, Sn is 0.01
~3.0wt% and a total of 0.015~5゜Qwt% of any one or two or more of Fe, Al, Ni, and Mn.
This is a corrosion-resistant copper alloy tube for refrigerant piping, characterized in that the remainder consists of Cu and ordinary impurities.

In addition, the invention of claim 2 includes 0.01 to 3.0 wt% of Sn and 0.015 to 5.0 wt% of any one or more of Fe, Af, Ni, and Mn in total. , and further P 0
．． 5 wt% or less, M g 0.1 w L% or less,
Si0.2wt% or less, Zn1. Contains any one or two or more types within the range of Ow t% or less, and the remainder is C.
This is a corrosion-resistant copper alloy tube for refrigerant piping, which is characterized by being made of u and normal impurities.

Furthermore, the invention according to claim 3 is the corrosion-resistant copper alloy tube for refrigerant piping according to claim 1 or 2, characterized in that the oxygen content is 1100 pp or less.

[Effect]

The significance of the addition of each alloying element in the present invention and reasons for limitation will be described below.

In the present invention, the addition of Sn improves the corrosion resistance of copper against ant nest-like pitting corrosion. Therefore, its content is reduced to 0.
．． 0.01w was limited to 01-3.0 wt%.
In the case of t% ungrooved, the improvement in corrosion resistance is not sufficient, and 3.0
This is because if it exceeds wt%, not only will the improvement in corrosion resistance be saturated, but also the workability, which is important in the manufacture of pipes, will deteriorate.

Furthermore, addition of one or more of Fe, Al, Ni, and Mn is effective in further improving corrosion resistance and strength due to the synergistic effect with Sn. The reason why the content was limited to 0.015 to 5.0 wt% in total was that if 0.015 wt% was not grooved, the synergistic effect with Sn would not improve corrosion resistance sufficiently.5. 0wt
This is because if it exceeds %, workability will deteriorate.

Furthermore, addition of one or more of P, Mg, St, and Zn acts as a deoxidizing agent to improve castability and corrosion resistance.

Therefore, the content should be 2015 wt% or less, M g 0.
1wt% or less, Si0.2wt% or less, Z n 1.
The reason why the content is limited to Owt% or less is because if the content exceeds the upper limit, not only will processability deteriorate, but also no further deoxidizing effect can be obtained.

Furthermore, in the invention of claim 3, the oxygen content is 1100
The oxygen content was limited to 1100 pp or less.
This is because if the conditions are as follows, the corrosion resistance will be further improved, and the risk of hydrogen embrittlement occurring during brazing, which is the main method for connecting the alloy tube of the present invention to equipment, can be suppressed.

〔Example〕

Examples of the present invention will be described below.

Copper alloy tubes with various compositions shown in Table 1 were melted and cast, hot extruded, and then subjected to cold drawing and annealing softening several times to produce an outer diameter of 9.53 mm and a wall thickness of 0.3 mm. Finished.

In addition, a phosphorus deoxidized steel pipe of the same size was prepared as a comparison material.

Corrosion resistance tests were conducted on these copper and copper alloy tubes using the apparatus shown in FIG. That is, the above-mentioned steel and copper alloy tube was cut into a length of 1300 mm to obtain Sample 1, and then inserted into an acrylic tube with an outer diameter of 40 mm, a wall thickness of 2 mm, and a length of 1000 mm, and both ends were connected to an upper rubber stopper 3 and a lower rubber stopper. 4
After fixing, a vent hole 5 with a diameter of 9 mm was opened in the upper rubber stopper 3, and approximately half of the internal volume was filled with tap water 6. Prepare such a device for the number of test samples, hold the tube axis vertically, and intermittently apply cooling water at 15°C to each tube at a flow rate of 2ffi/min from the bottom to the top of the tube. (After running for 15 minutes, interrupting for 105 minutes) By running it for 45 days,
Condensation conditions, temperature conditions, and ventilation conditions similar to those for refrigerant piping were reproduced. The temperature of the room in which this device was installed during the test period was 25 to 30"C. After the test, in all samples, the outside part of the sample that was in contact with air inside the acrylic tube 2 was replaced with Ant nest-like corrosion similar to that occurring in steel pipes occurred, and the maximum corrosion depth was measured in order to compare the extent.The results are also listed in Table 1.

As is clear from Table 1, the copper alloy tube of the present invention No.

1 to 21 all have a higher Sn content, Fe, and AI than conventional steel pipe No. 26 and the copper alloy pipe of the present invention! Compared to comparative copper alloy tubes No. 22 to 25, which have a low content of one or more of Shirakawa's Ni and Mn, the maximum corrosion depth is very shallow and the peculiarity is that it has an ant nest shape. It has outstanding corrosion resistance.

In particular, excellent corrosion resistance was obtained in the copper alloy tubes Nos. 5 to 10.16 to 21 of the present invention, in which the oxygen content was 1100 pp or less.

〔Effect of the invention〕

As described above, the copper alloy pipe according to the present invention exhibits excellent corrosion resistance even under the condensation, temperature, and ventilation conditions that are unique to refrigerant piping, and is suitable for various equipment such as condensers, single generators, and compressors. It has remarkable industrial effects, such as being able to extend the life of the connected refrigerant piping material.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of a corrosion resistance testing apparatus used in the present invention. 1--sample, 2-acrylic tube, 3-upper rubber stopper,
4--Lower rubber stopper, 5--Vent, 6-Tap water, 7
-Air. Patent applicant Furukawa Electric Co., Ltd.

Claims (3)

[Claims] (1) 0.01 to 3.0 wt% of Sn, Fe, Al,
One or more of Ni and Mn in total of 0.01
A corrosion-resistant copper alloy tube for refrigerant piping, characterized in that it contains 5 to 5.0 wt%, with the remainder consisting of Cu and ordinary impurities. (2) 0.01 to 3.0 wt% of Sn, Fe, Al,
One or more of Ni and Mn in total of 0.01
Contains 5 to 5.0 wt%, further P0.5 wt% or less, Mg
0.1wt% or less, Si0.2wt% or less, Zn1.0
Contains one or more types within the range of wt% or less,
A corrosion-resistant copper alloy tube for refrigerant piping, characterized in that the remainder consists of Cu and ordinary impurities. (3) The corrosion-resistant copper alloy tube for refrigerant piping according to claim 1 or 2, characterized in that the oxygen content is 100 ppm or less.