ES2249879T3 - METHOD OF MANUFACTURE OF COPPER TUBES WITH ITS INTERNAL SURFACE COVERED BY TIN BY ELECTROLYSIS. - Google Patents

Abstract

A method for tin-coating the internal surface of a copper tube followed by consecutive degradations until its end dimension is achieved. In this way, a cohesive tin layer is achieved, with excellent adherence and controllable thickness, so that the long-term yield of copper ions in water remains much lower than the required marginal values for potable water, even in cases where pH is lower than 6.5. The copper tube produced in this way is appropriate for use in water supply networks with problems in the potable water.

Description

Copper tube manufacturing method with its internal surface covered with tin by electrolysis.

The invention refers to a method of manufacture of copper composite installation tube and whose inner surface is covered with a cohesive layer of tin.

Also, the invention also refers to the use of this copper tube as installation pipe that releases low levels of copper ions to drinking water with a lower pH to 5.5.

Copper pipes without welding are used as installation pipes, especially for water circulation drinking, complying with the allowed requirement of 3 mg / l maximum of ions released in water after 12 hours at rest.

If the copper tube is used for the transfer of drinking water with a pH below 6.5 and / or with a high content of "carbonic acid" in free phase
(Kg> 1.0 mol / m 3), it is advisable to reduce the release of copper ions.

So far there have been tests throughout the world to achieve this goal.

One of these tests was to cover the Inner face of copper tube with pure tin powder and subsequently apply an incandescent treatment. This form the copper and tin will form an alloy of 25 to 35 mm. from thickness. The drawbacks of this method is that this layer has a very short duration and that the release of ions increases with the weather.

Also, for several years a known chemical process for galvanizing the inner side of the tube coppermade. In relation to the cohesive capacity of tin and with its adhesion to copper, this process is inferior.

The aim of this invention is to manufacture tube of copper composite installation and whose internal surface is cover of a cohesive layer of excellent adhesion and thickness controllable so that the future release of copper ions in the water is much lower than the necessary marginal values indicated above.

In this way, this invention serves to galvanize by electrolysis the inner face of the copper tube, after hot extrusion or cold forming, following the steps listed below:

to.

Clean the copper tube using a electrochemical process

b.

Galvanize by electrolysis introducing the tube into a tank full of electrolyte solution with electrode movement inside. The speed of continuous movement of the electrode and the intensity of the current is fixed depending on the desired final thickness in the galvanized of the inner face

C.

To wash and dry the galvanized tube.

The deformation of the cross section of the copper tube by one or more shaped, until the final dimensions are reached.

This invention results in a galvanized layer on the inner side of the copper tube, cohesive (without pores) and of excellent adhesion and thickness
controllable.

The advantages mentioned above are the result of the electrolytic method used.

In this way the release is assured reduced copper ions in drinking water, which remains for below 1 mg / l levels after 12 hours at rest. Is important to note that internationally it tends to reduce the maximum allowed limit of 3 mg / l.

The invention is described in detail below, with reference to the attached images, of which:

Figure 1 (at 1:20 scale) shows a view side (top of the image) and a cross section (bottom) of the general layout of the installation for Galvanize the inner face of the copper tube by electrolysis.

This view shows the galvanizing tank (1) with a 12 meter tube (2) submerged inside it, with a constant electrolyte level (3). The electrolytes are continuously in recirculation by means of a pump (4), they are cleaned thanks to a filter (5) and are collected in an electric resistor (6) inside a heating tank (7).

The tin anode (8) rests on the end of a bar with electrical insulation (9) with the ability to move horizontally thanks to a conveyor bar (10). At bar end (11) is the connector connection positive of a direct current energy source while that the negative source connector appears (12) in the tube copper.

The bottom of the figure shows a cut transverse of the installation, where the device to collect the copper tube from an initial buffer (13) thanks to a conveyor belt (14), cleaning system (15) and buffer intermediate (16) before the galvanized tank. It also also you can see the cleaning tanks (17 and 18), the final storage and the drying zone (19).

Figure 2 (at a scale of 1:20) shows the scheme of the electrolytic tank with the tin anode (8) in the point where the electricity supply starts.

Figure 3 (on a scale of 1: 5) shows in detail the galvanized tank (1) from the side where the Tin anode (8) enters figure 1.

The image also shows the tin anode (8) resting on the bar (9). This bar is electrically insulated by insulation (20). It is supported on a support roller additional (21) and its front part is by supports (22) that guide the electrode concentrically towards the tube (2).

According to this invention, galvanization by electrolysis takes place on the inner side of the tube composed of deoxidized copper through phosphorus, after the extrusion stage in hot or after cold forming.

The length of this tube ranges between 2 and 25 meters, its internal diameter between 40 and 150 mm. and its thickness between 3 and 15 mm. The internal surface should also be exempt of oxides and particles of any nature. For this you can Use electrochemical procedures.

To introduce the tubes into the tank Electrolytic mechanical procedures are used. The length of This tank exceeds at least 200 mm. that of the copper tube, and its depth and width should be appropriate according to the number of pipes that will be galvanized.

As a anode a tin wire of cylindrical shape and with a diameter smaller than the internal diameter of the copper tube. The same copper tube performs the function of cathode and salts commonly used for galvanizing in An acidic environment works as an electrolyte. The conditions of galvanized, that is, the composition of the bath; the temperature and The current density are the standards, known and recommended by electrolyte suppliers.

A mechanical clamp picks up the copper tube that is find it in a storage place and place it on stands with a uv (v) shape inside the galvanized bath. Immersion of this tube in the bathroom is produced at an angle to facilitate the total coating (see figure 1).

Set the tube and then insert the tin anode, supported on a conveyor bar, until reach its other end (see figure 2). The tin anode is It consists of a pure tin cylinder with a diameter between 10 and 20 mm less than the internal diameter of the copper tube and a length greater than 100 mm.

The concentric movement of the anode cable of tin inside the tube is secured by the embedded supports between the tin anode cable and the conveyor bar (see figure 3).

When the anode reaches the end of the tube (see Figure 2), a current power source will be connected direct, whose negative connector will go to the tube and the positive to the cable of tin anode, at the same time that the bar begins to be withdrawal. The withdrawal speed and intensity used depend on the desired thickness of the galvanized, which can not exceed 30 mm The current will be applied during the withdrawal process of the bar (so that the mud supports do not damage the galvanized surface) and will be interrupted when the cable Tin anode reach its end.

After removal of the tin anode cable, the tube, already galvanized, will be transported thanks to a clamp two consecutive cleaning tanks, and will finally be located in the place for drying and storage. For washing it employs a known technology that eliminates all waste using deionized water.

The tube, already galvanized, goes through successive shaped to reach the desired dimensions.

Claims (3)

1. A method for manufacturing a copper composite installation tube with an internal galvanized face and characterized in that the galvanizing has been carried out by electrolysis of the internal face of the copper tube after hot extrusion or cold forming, followed of the deformation of the cross section of the copper tube by one or more shapes until reaching the desired dimensions
you give. 2. A method according to claim 1 characterized by the following partial steps in the production process:

to)

Clean the copper tube using a electrochemical process

b)

Galvanizing by electrolysis by immersing the tube in a tank filled with electrolyte solution with electrode movement inside, characterized in that the speed of the continuous movement of the electrode and the intensity of the current are set depending on the desired final thickness in the galvanized internal face .

C)

To wash and dry the galvanized tube.

3. A method according to claim 1 characterized in that the copper tube is used as an installation tube, which reduces the release of copper ions in drinking water with a pH below 6.5 and / or a concentration Especially high in free phase carbonic acids (Ks> 1.0 mol / m3).