Classifications

• • C—CHEMISTRY; METALLURGY
  • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
  • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
  • C23C2/00—Hot-dipping or immersion processes for applying the coating material in the molten state without affecting the shape; Apparatus therefor
  • C23C2/04—Hot-dipping or immersion processes for applying the coating material in the molten state without affecting the shape; Apparatus therefor characterised by the coating material
  • C23C2/08—Tin or alloys based thereon
• • C—CHEMISTRY; METALLURGY
  • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
  • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
  • C23C2/00—Hot-dipping or immersion processes for applying the coating material in the molten state without affecting the shape; Apparatus therefor
  • C23C2/34—Hot-dipping or immersion processes for applying the coating material in the molten state without affecting the shape; Apparatus therefor characterised by the shape of the material to be treated
  • C23C2/36—Elongated material
  • C23C2/38—Wires; Tubes
• • C—CHEMISTRY; METALLURGY
  • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
  • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
  • C23C8/00—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals
  • C23C8/06—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using gases
  • C23C8/08—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using gases only one element being applied
  • C23C8/10—Oxidising

Definitions

• the invention relates to a method and arrangement defined in the preambles of the independent claims for coating copper or copper alloy pipes.
• the dissolution of the copper from pipe for instance in household water has been effectively restricted and prevented by coating the inner surface of the copper pipe for example by tin, which provides a cathodic protection for the copper.
• Tin is non-toxic, has a good corrosion resistance and a good appearance, and owing to these properties it has been widely used as a protective coating for metals.
• a prerequisite for a successful coating is a carefully performed pretreatment of the surface to be coated. The purpose of the pretreatment is to remove the fabrication grease and carbon films that are accumulated on the pipe during the earlier manufacturing steps.
• pretreatments it is well-known to use acids or other strong solutions with several rinsing steps before coating.
• Known prior art solution pretreatment processes are alkaline cleaning, acid cleaning, surface activation and preliminary coating.
• the pretreatment is carried out by a mechanical cleaning method, for instance by sand blasting.
• copper pipes are bright annealed in a normal process.
• oxygenous air is removed from the pipe by vacuum treatments and gas circulations, and the air is replaced by an oxygen-free gas, which is fed in to prevent the inner surface from oxidation.
• the pipes are annealed, and the fabrication greases start to vaporize, whereafter the vaporized particles are removed from the pipe by a powerful protective gas circulation.
• the fabrication grease still leaves a very thin and compact carbon film on the inner pipe wall, and tin coating cannot be applied directly on the wall without pretreatment.
• the object of the invention is to introduce a new solution for performing the pretreatment applied in the interior coating of copper or copper alloy pipes.
• solvent pretreatment methods can be replaced by pretreating the copper pipe in connection with the normal production, so that an oxidized layer is created on the inner pipe surface.
• the invention relates to a method for coating the interior wall of copper or copper alloy pipes by a protective film, particularly a tin film, according to which method the pipes are before coating subjected to a pretreatment, where the pipes are treated in at least one temperature reactor, so that on the inner pipe surface, there is created an oxidized layer.
• on the inner pipe surfaces there is blasted process gas for burning the carbon-bearing materials contained on the inner pipe surfaces and for oxidizing the copper.
• the fabrication greases are burned in the presence of oxygen, so that they are combusted into carbon dioxide or other corresponding compounds.
• the inner pipe surface is oxidized, which provides an advantageous base for the tin coating.
• process gas is blasted on the inner pipe surfaces before the temperature reactor.
• process gas is blasted on the inner pipe surfaces in the temperature reactor.
• pipes are insulated against the exterior atmosphere before feeding the pipes in the temperature reactor.
• pipes are insulated against the exterior atmosphere so that they are closed at both ends by welding.
• the process gas blasted on the inner pipe surfaces contains 21 % oxygen, and the rest is nonreactant gas.
• the process gas contains more than 21 % oxygen, and the rest is nonreactant gas.
• the process gas contains less than 21 % oxygen, and the rest is nonreactant gas.
• the pipes are heated at the temperature of 100 - 1000 degrees Centigrade, preferably at 500 - 800 degrees Centigrade.
• the pipes are heated in the temperature reactor preferably for 0 - 50 minutes.
• the pipes are inserted essentially completely in the temperature reactor.
• the pipes are inserted in the temperature reactor, so that part of the pipes is left outside the reactor.
• the oxidized layer created during the pretreatment step is composed of at least one compound, which is created when oxygen reacted with copper, such as the copper oxidule (Cu 2 0) of univalent copper (Cu + ) and/or the copper oxide (CuO) of bivalent copper (Cu 2+ ).
• the pipes are coated by a tin film immediately after the pretreatment. It also is possible that the pipes are stored and coated by tin film in a separate process.
• the pipes are cooled before coating with tin.
• the inner pipe surfaces are cleaned prior to the tin coating. In the cleaning step, there are removed possible oxidation scales and other solid particles created in overoxidation, before starting the tin coating step.
• the pipes are pressure cleaned by cleaning gas.
• pipes are pressure cleaned by cleaning liquid.
• the pipes can also be subjected to straightening and shaping treatments before or after tin coating.
• One alternative is to employ an induction furnace as the temperature reactor.
• the invention also relates to an arrangement for coating the inner surface of copper or copper alloy pipes by a protective film, particularly by a tin film, so that before the coating, the pipes are subjected to a pretreatment, and the arrangement used in the pretreatment comprises means for supplying process gas onto the inner pipe surfaces, and at least one temperature reactor for heating the pipes, so that on the inner pipe surface, there is created an oxidized layer.
• the method and arrangement according to the invention in the pretreatment of copper or copper alloy pipes, the harmful multi-step prior art solution treatments can be avoided, and the pretreatment process itself is speeded up.
• Another advantage of the pretreatment process according to the invention is that the appearance or other properties of the pipe, such as hardness or softness, are not set as obstacles for performing the pretreatment.
• FIG. 1 A method according to the invention, illustrated as a diagram in principle
• FIGS 1 and 2 there is illustrated as a diagram in principle a method according to the invention for pretreating hard copper pipes, either straight pipes 1 or pipe coils 8, in preparation for coating the inner pipe surfaces by tin.
• the straight pipes 1 are longer than the nominal measure by the length of the deformation allowance.
• the inner pipe surfaces contain impurities, such as drawing oil.
• the example blasted process gas 2 containing oxygen in a batch of 21%, and the rest is nonreactant gas.
• the process gas is meant for burning the carbon-bearing materials contained on the inner pipe surface, and for oxidizing the copper.
• the pipes that are closed by welding are transferred to be treated in a temperature reactor 4, where the pipes are heated preferably at the temperature of 600 degrees for the duration of 10 minutes.
• the employed temperature reactor is any known closed-circuit temperature reactor, where the pipes can be heated at different temperatures for the required duration.
• the oxygen contained in the process gas reacts with the carbon contained in the drawing oils into carbon dioxide, and the excess oxygen reacts with the copper, creating an oxidized layer and binding the free copper atoms of the surface against further contaminations.
• the pipes can be installed in the temperature reactor either all at the same time or one by one. In connection with the temperature reactor, there also are removed the lubricants 6 that were vaporized in the annealing process.
• the size of the temperature reactor is designed to be in proportion to the number and size of the pipes to be processed.
• the pipes are cooled in the cooling unit 5 for a desired duration before the tin coating step. According to the example, the pipes are cleaned in a cleaning unit 9 by pressurized cleaning gas of solid particles that are possibly left on the inner pipe surfaces. In the temperature reactor treatment, the inner surface of a copper pipe becomes an ideal base for tin coating.
• the pipes are either transferred to a storage to wait for the tin coating, or directly to be tin-coated in the tin coating process 7.

Landscapes

• Chemical & Material Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Engineering & Computer Science (AREA)
• Materials Engineering (AREA)
• Mechanical Engineering (AREA)
• Metallurgy (AREA)
• Organic Chemistry (AREA)
• Cleaning And De-Greasing Of Metallic Materials By Chemical Methods (AREA)
• Chemical Vapour Deposition (AREA)
• Chemical Treatment Of Metals (AREA)
• Application Of Or Painting With Fluid Materials (AREA)

Applications Claiming Priority (3)

Publications (1)

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• 2002
  • 2002-12-18 FI FI20022216A patent/FI120359B/fi not_active IP Right Cessation
• 2003
  • 2003-11-24 EA EA200500551A patent/EA011199B1/ru not_active IP Right Cessation
  • 2003-11-24 WO PCT/FI2003/000897 patent/WO2004055230A1/en not_active Ceased
  • 2003-11-24 AU AU2003283454A patent/AU2003283454A1/en not_active Abandoned
  • 2003-11-24 EP EP03775422A patent/EP1573082A1/de not_active Withdrawn
  • 2003-12-15 TW TW092135357A patent/TW200416303A/zh unknown

Non-Patent Citations (1)

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