NL8004409A - METHOD FOR MANUFACTURING TUBES, SO MANUFACTURED TUBES, AND THE USE THEREOF FOR CONDUCTING WATER AND THE LIKE. - Google Patents

Description

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Lx 5715. Method for manufacturing pipes, pipes thus manufactured, and their use for conducting water. And the like

The invention relates to a method for painting. manufacturing pipes of copper or copper alloys intended for; ; · Conducting cold or hot water, such as for water supply for ... houses, for central heating, and in condensers and heat exchangers. The invention further includes tubes thus manufactured, and their use, particularly in condensers and heat exchangers

Mainly copper or copper pipes are now used. rings for water supply and in condensers and heat exchangers, the latter eg in power plants of various kinds, .10 in oil refineries, on board ships, in the chemist; j V;.; industry, in seawater desalination plants and the like For example, such pipes utilize in particular the good overall resistance to attack of copper and its alloy, and its excellent thermal conductivity due to various additions of alloying elements. , and to a certain extent also by different post-treatments, certain types of damage to which such pipes are subject can be avoided. · A general consideration can be found in an article by O.Breckon and JRT. Baines in J. MarirEngrs. (1955): 1 * 10 »| A special form of deterioration is formed by the occurrence of local fine holes, which very quickly lead to the leakage of coolant or the like, and thereby become unusable. 25 pipes may lead · The occurrence of such holes] must be attributed to the use of oil during the pulling of the pipes, which decomposes oil during the final annealing of the pipes, releasing carbon particles · 1 Er Various methods have already been proposed to remove these drawing oil residues, or to prevent the formation of carbon deposits therefrom, or to remove such precipitate by aftertreatment.

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In order to remain below an amount of 200 mg / m, a degreasing agent, such as, for example, trichlorethylene, is injected into the tubes, especially in coiled tubes, before annealing, in order to leave a residual amount of oil, which turns into carbon deposition may give rise to decrease. After implementing -2- i

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the degreasing liquid is then fed a water vapor stream through the tube, which then entrains the remains of the solvent *

Furthermore, it has already been proposed to reduce the amount of residual carbon after annealing by sending a mixture of air and abrasive particles, eg from alumina or silicon carbide, through a tube at high speed. However, this method cannot be applied to coiled pipes, and is only suitable for straight pipe sections. After all, the reduction in speed of the abrasive particles when they collide with the pipe wall in the bends is too great to obtain an even removal of carbon deposits or the like in coiled pipes with these 10 particles * 2

Finally, a residual carbon content of 30 mg / m was successfully achieved by injecting a gas mixture of oxygen and inert gases into the tubes before their heat treatment.

During annealing in an oven, generally in a reducing environment, the oxygen reacts with the hydrocarbons remaining in the interior of the drawing tube to form volatile gases, such as carbon monoxide and / or dioxide, which gases can be easily removed. The oxygen content within the tube is thereby adjusted such that, in particular, the formation of powdered oxide deposits during annealing is avoided. This leads to difficult to control working conditions during machining on an industrial scale *

All of the aforementioned operations are difficult to achieve in practice when it comes to manufacturing large quantities of pipes, while these operations are difficult to reconcile with continuous production of copper or copper alloy pipes.

The object of the invention is to avoid the drawbacks of the known methods, and in particular provides a simple and inexpensive treatment for copper or copper alloy pipes for the aforementioned purposes *

The intended results can be obtained by means of a method comprising at least the following successive steps: - treating a strip of copper or a copper alloy in an oxidizing environment at such a temperature and for a period of time that after the annealing, a reduction in the carbon content below a certain value is obtained, in order to avoid hole formation due to the deteriorating effect of the water with which the tube comes into contact; 8904409-3- cleaning the surface to prevent non-adhering deposits on at least one side of the tire and on the edges thereof; - welding the tape into a tube in a known manner, the inner surface of the cleaned surface forming the inner surface

The carbon content is generally reduced to less than 200 mg / m; in many cases it is even beneficial to reduce to 2 2 30 mg / m, or even to 5 mg / m. The method according to the invention readily makes it possible to obtain contents of less than 2 mg / m without any difficulty, which is due to the fact that the starting tape is fully accessible for oxidation, which is the case with pipe sections with long length, and in particular coiled pipes, is not possible

The operating conditions, and in particular the temperature and duration of the oxidation bath operation, as well as the oxygen content of the gas mixture used, will be easily determined by the skilled person, and in particular taking into account the manufacturing requirements, in order to achieve the above values at least.

The advantage of this mode of operation compared to the internal oxidation of a tube is the very high regularity of the oxidation operation. Indeed, during this operation it is not possible to achieve a complete solid gas composition and other working conditions within a tube, since the combustion of the residual oil leads to the formation of carbon monoxide and dioxide, while the gas mixture is introduced at one end of the tube, and the combustion gases are removed together with the excess gas on the other end of the pipe. The known operations necessarily lead to irregularities resulting from changing uncontrollable oil concentrations in the tubes and irregular oxide deposits.

It is further noted that most known operations do not allow to obtain as low carbon contents as is possible with the present process, nor to achieve a surface finish and an adapted composition of the surface layer, as is possible according to the invention . It is only necessary to think of the difficulties which the effective sanding of a straight tube, and thus certainly of a bent or wound tube, would entail.

In order to ensure good utilization of the equipment / devices required for such processing, it is advantageous to manufacture the houses in a continuous manner, so that the preceding oxidation and cleaning operation is preferably also continuous does not need to be carried out · 5 The oxidation treatment necessarily leads to the formation of an oxide layer on the surface of the tape which cannot be completely removed during brushing or sanding · However, it has been found that, contrary to what is generally believed, a such an oxide film is not necessarily harmful provided it is not porous, fragile and / or poorly adhesive. Surprisingly, it has been found that the removal of such deposits after the oxidation treatment is sufficient to obtain a product of excellent quality, avoiding all difficulties caused by the appearance of fine holes, even the presence of very strong attacking water. .

A suitable choice of the method of removing such deposits may be to remove only any non-adherent, porous and fragile deposits that may have formed, or carry out a complete removal, removing both the non-adherent and the oxides -20 deposits. .

The cleaning of the surface can be accomplished by brushing, sandblasting or etching, depending on the final desired surface quality.

This again takes advantage of the possibility of treating an accessible surface of arbitrary size, which cannot be done, or is very difficult, with large length pipes, since it is difficult to obtain the necessary means (brushes, sand or an etching liquid) by a pipe. In particular, it is practically impossible to perform an effective sanding operation on pipes with a diameter of more than 22 mm, or on annealed pipes that are rolled up.

The cleaning treatment according to the invention can be carried out fully automatically, and can proceed continuously after the oxidation operation.

This method also has the advantage that the edges of the belt can be treated at the same time, so that they are sufficiently cleaned, which is a prerequisite for performing a good welding operation.

Welding for forming a tube is effected in the known CO way in devices which can preferably operate continuously, which devices are known. For this purpose, reference may be made, for example, to the book "Herstellung von Rohren", Verlag Stahleisen mbH, Düsseldorf, -> This method is particularly suitable for the manufacture of houses which have to comply with special shafts, eg, such as described in FR patent application 8002 500 (05 * 02.80) from the same applicant.

The improvement provided by the invention over the prior art methods of treating tubes after molding them lies in the full controllability of the operating conditions for reducing the carbon content and removing all or part of it. oxide deposits. In this way it becomes possible to obtain a product of which the pipe section which is in contact with attacking liquids has the same suitable surface quality everywhere.

Since the oxidation and cleaning treatment is carried out on a flat and accessible surface, not only is a better result of these treatments obtained, but it is also possible to continuously observe and examine the result, which is not easy with a tube. , and in particular not visually, is possible.

Finally, it is pointed out that gases formed in the oxidation operation according to the invention can be removed continuously and easily, while in the known operations in a tube there is always a risk of condensation.

It is further noted that a tube obtained according to the invention, after forming it, which takes place after the oxidation and cleaning operation, can still be subjected to other operations, which may be desirable to add the tube to a special way of 50 fit to adjust.

Such operations may be purely mechanical, such as scraping the internal weld seam, sizing, etc., or of a physicochemical nature such as annealing, or other processing such as coiling after annealing, etc. Alloys suitable for treatment in the manner of the invention are arsenic copper (Cu 99.40%, Ash 0.40 P 0.025? 5), phosphorus copper (Cu 99.9 P 0.025%), brass 70/90 (Cu 70 Zn 30 "Admiralty brass" 70/90/1 (Cu 70 Zn 29%

Sn 1%), brass 76/22/2 (Cu 76 Zn 22 #, Al 2 #), copper-nickel 90/10 (Cu 90 #, Ni 10 #, Fe 1.4 #, Mn 0.75 copper- nickel 70/30 ♦ -Ar (Cu 70 #, N. 30%, Fe 0, b #, Mn 0.75 #), copper-nickel 70/30 with iron (Cu 70 #, Ni 30%, Fe 1, 5 #, Mn 1.5 $), aluminum bronze (Cu 9k%, Al 6 ίο), etc. This specification includes the main intended alloys, but is not exhaustive, since the invention is generally available in all 5 available alloys can be used ··

The tubes manufactured according to the invention are distinguished by a fixed quality. With the same quality, the manufacturing costs are lower than for the known tubes. Furthermore, these tubes are not flattened, like drawn tubes.

The duration of the oxidation operation used in accordance with the invention depends on the throughput of the belt through the oven.

Generally, the feed rate in the reactive range is 1..3 min when the oven temperature is 66..810 ° C.

Such pipes can be used for all common applications of pipes of this kind.

The invention will be further elucidated hereinbelow with reference to some examples, given by way of example and without limiting intention, in which the treatment method according to the invention (example I) and a complete manufacturing operation for the manufacturing of copper pipes (example II) has been described

Example I

A copper or copper alloy tape was unwound at a speed of about 0.35 m / s, and passed continuously through a bath of trichlorethylene, in which most (about 95%) of the oil remaining on the tape was removed . This belt was then passed continuously through a tunnel oven, in which the middle section had a temperature of 6β · 8 6 ° C, which oven was heated with an excess of air. At the exit of the oven; 30, with cutting tools, removed the oxide layers present on the side edges of the belt at a depth of 0.25 mm, in order to obtain a chemically pure metal surface. The tape was then passed through nine stages of forming rollers, which bent the tape into a tube. A spool of hollow copper wire of square section 35 (10x10x2 mm), through which a water flow of 3 l / s was passed, which spool was fed with an alternating current of 350 kHz, heated the edges of the formed tape. At the same time, the tube was rolled up by means of forming rollers, the interspace of which corresponded to the final desired pipe diameter, in which rolling operation a displacement of the axis direction of 0.35 mm occurred. A pedestrian saw finally cut the desired pipe lengths

To obtain a tube, the inner surface of which is free from oxides, the aforementioned oxidation operation in the oven was followed by brushing with bronze brushes (0.3 mm bristles) driven at a speed of 2 rev / s, which brushes moved alternately in the axis direction over 12 mm #

In order to obtain an oxide-free inner surface, the oxidation operation in the oven could also be accompanied by an abrasive grinding with alumina particles, the dimensions of which were 12 .mu.mu.m while their speed was m / s.

In order to obtain an oxide-free inner surface, an etching operation could also be carried out, in which the belt was continuously passed through 13 a 25% sulfuric acid solution.

Example II

The copper was melted in a round furnace with refractory lining and induction heating to obtain a completely homogeneous metal. In the bottom of the furnace was an opening of rectangular cross-section with a height of 30 mm and a width equal to the circumference of the pipe to be welded, plus 5 mm for each edge. The rectangular opening was surrounded by a double-walled copper ring, through which cold water could pass. This copper window was provided on the inside with graphite pieces 25 to obtain sufficient lubrication of the metal during its solidification. The solidifying band was removed with mechanical aids. The manufacturing speed was approximately 0.7 m / s. At the exit of this device, the belt had a temperature of about 650 ° C, after which the belt was fed into a preheating induction oven of 850 ° C. In four successive steps, the thickness of the tape from 30 mm to k mm was reduced by hot deformation, after which the final wall thickness of the pipe to be formed was achieved by cold deformation. The edges were then cut to a width of 5 mm by rotary knives, after which the tape was passed through an annealing furnace in a running manner. Finally, the treatment of Example I was carried out, after which the tape was bent and welded into a tube.

Claims (5)

1. A method of manufacturing copper or copper alloy corroding pipes in the form of small holes, characterized in that a copper or copper alloy strip in an oxidizing environment at such a temperature and for a period of is treated for such a time that after annealing, a reduction in the carbon content below a certain value is obtained, in order to form small holes during use due to the deterioration effect of the water with which the formed tube comes into contact, avoid subsequently cleaning the surface to remove non-adherent deposits on at least one side of the tire and at its edges, and sealing the tire in a conventional manner in a tube, the cleaned surface hin surface of the tube forms # 2 # Method according to claim 1, characterized in that the carbon content is reduced to less than 200 mg / m. The method according to claim 2, characterized in that the 2 carbon content is reduced to less than 30 mg / m. The method according to claim 3t, characterized in that the 2 carbon content is reduced to less than 2 mg / m. Method according to any one of the claims, characterized in that the oxidation treatment is carried out at a temperature of 650-810 ° C for 60..180 s. 6. Method according to any one of claims 1..5, characterized in that the surface is cleaned by brushes. Method according to any one of claims 1 ** 5i, characterized in that the cleaning of the surface is carried out by sanding with granular material. 8. A method according to any one of claims 1..5 *, characterized in that the cleaning of the surface is effected by etching. Tubular product obtained by using the method according to any one of claims 1..8. 10. Tube according to claim 9, used as a tube for conducting water. 8004409