EP1893462B1 - Method for the anticorrosive treatment of hollow bodies, method for producing a metallic structure treated according to said method, and method for maintaining the structure - Google Patents

Description

The invention relates to protective treatment methods for hollow bodies or hollow metal structures against corrosion.

The metal structures in question here are large structures with difficult-to-access surfaces for depositing an anti-corrosion paint by brush or spray. They are hollow to reduce the weight.

This is particularly the case for structures such as those used in the construction of bogies or chassis of railroad cars, comprising hollow bodies, sleepers, cleats or other profiles, supporting the floors or the walls of these wagons. The field of application of the invention is of course not limited to rail transport, any other form of transport or any other field of construction which can perfectly constitute a field of application of the invention.

It is therefore difficult to protect the interior of these hollow bodies other than with the angled brush or with a paint spraying tool, such as a spray gun or a specific nozzle, the immersion in baths anti-coating. corrosion is not possible because of the size of the hollow bodies, before assembly, or structures they reinforce, after assembly.

All methods today are very expensive because they require a lot of manpower and a lot of time.

It was while seeking a more economical solution that the plaintiff had the idea of her invention.

For this purpose, the invention relates to a maintenance method according to claim 1.

By injection, we easily reach all difficult to access surfaces that are to be protected. It may be, for example, sleepers or metal profiles constituting the crate structures or underbody bodies that require effective anti-corrosion protection. At the same time, since the cellular foam remains in place after application, these surfaces, when it comes to floors, are covered with a material impervious to water or cleaning detergents and which contributes to the protection against corrosion.

Preferably, a mixture of a first expansion component of a second anti-corrosion agent support component is injected to produce the anti-corrosion foam and flame retardant or thermal insulation.

It thus becomes possible to carry out subsequent assembly or disassembly operations, for example by welding, without damaging the anti-corrosion protection of the immediate environment of the zones of the protected structure that are the objects of these operations, or cleaning operations. without any prior disassembly.

• la figure 1 est une vue en perspective d'une structure comportant des surfaces difficiles d'accès, à protéger contre la corrosion et
• la figure 2 est une vue en perspective d'une structure de plancher de wagon de chemin de fer et qui comporte une partie à réparer.

The invention will be better understood with the aid of the following description of the anti-corrosion protection treatment process according to the invention, with reference to the appended drawing, in which:

• the figure 1 is a perspective view of a structure with difficult-to-access surfaces, to be protected against corrosion and
• the figure 2 is a perspective view of a railway car floor structure and includes a part to be repaired.

With reference to the figure 1 a structure 1 liable to be subjected to corrosive attack, either by the ambient air or by the water, in particular when cleaning with detergents, comprises sheet blanks 2, 3, or more, assembled by metal cleats 4, serving as spacers.

The cleats 4 are hollow and have surfaces 5 which must be completely guaranteed of any corrosion but are difficult to access by brush or spray gun required for the deposition of a primary paint.

The assembly being performed by welding, it is not possible to apply a layer of protective paint on the surfaces of the sheets 2, 3 and the cleats 4 separately, for example on the one hand by brush and on the other hand in a suitably sized container and containing an antioxidant bath, so as to bathe the surfaces 5 completely. The welding operation would destroy locally the protection just applied. And the complete structure 1 is too important to be treated by bath.

• on assemble la structure 1 non protégée,
• on injecte simultanément, au moyen d'un pistolet à deux becs, deux composants A et B, A étant une mousse alvéolaire minérale à laquelle on a ajouté un agent anti-corrosion et des pigments d'adhérence, et éventuellement des agents ignifuge, isolant thermique, phonique, ... et B, un produit provoquant l'expansion de la mousse alvéolaire A, quand A et B sont en contact.

Then proceed as follows:

• we assemble the unprotected structure 1,
• two components A and B are simultaneously injected by means of a two-nozzle gun, A being a mineral cellular foam to which an anti-corrosion agent and adhesion pigments have been added, and possibly fire-retardant, insulating agents. thermal, phonic, ... and B, a product causing the expansion of the foam A, when A and B are in contact.

The expansion of component A transports the additional agents supported by the foam on all parts of the surfaces 5, even those that are out of sight, and guarantees their complete protection.

Foamed foam A thus expanded remains in place after application to cover all surfaces, which waterproofs the structure 1 and contributes to its anti-corrosion protection. If necessary, it is possible to integrate an impervious elastic agent into the cellular foam A.

For A and B, a two-component mineral product is preferred, which is composed of either an ablative silicone, which is converted into energy-consuming, and intumescent, with formation of thermal insulating foam, or components minerals and usually two bases, for example a zinc phosphate and a limestone, such as calcium carbonate. These products also have the advantage of being soluble in water, which facilitates rinsing and makes it non-polluting. Products such as polyurethane have the disadvantage of being flammable while isocyanates require rinsing solvents tools, unacceptable for the environment.

For example, one of the compositions proposed in document WO 97/19033 A1 forming a non-flammable, adhesive inorganic resin layer, applied to the surface covering to be protected, for use with an expansion component set in sufficient proportion to provide foamed expanded foam capable of being expanded in proportions commensurate with the intended purpose herein .

The minerals used are composed mainly of combinations of phosphates and calcium carbonates, especially plasticizers such as dibutyl phthalate, dioctyl, cyclohexyl, or dimethylglucol, or such as benzyl benzoate, castor oil, ricinoleate glycerol or methyl, octyl adipate, heptanoate or pentaerythritol butyrate or dipropylene glycol, or glycerol or dipropylene glycol butyrate, camphor.

With regard to plasticizers which are also flame retardant, it is possible to choose from tricresyl phosphate, triphenyl phosphate or trichloroethyl phosphate.

Finally, pigments improving the sound insulation can be added.

To reduce the amount of material needed, a filler such as hemp or other inexpensive components may be added. The quantity of product necessary, and therefore its cost, is reduced accordingly.

Environmental tests, in particular with salt spray, were carried out on hollow bodies, treated according to the method of the invention. The latter, in this case metal hollow bodies, are cut transversely after exposure to salt spray for 1000 and 1500 hours so as to allow a visual observation of the result obtained. Other tests, with transparent plastic bodies, so as to allow a visual observation of the expansion and propagation of the product, show the efficiency of the process.

And the above means, pistol and products A and B, make it possible to realize much better price a metal structure only by implementation of the assembly steps of the structure 1, 2, 3, 4, and then treatment of the anti-corrosion protection of surfaces 5 difficult to access.

These means are particularly suitable, with reference to the figure 2 , at the realization and maintenance (also called mid-life operation) of the floor structures 10, or partition, railway cars.

The example of structure 10 of the figure 2 here comprises a wooden floor 11 and a metal frame 12 in the image of the structure of the figure 1 . It comprises metal sheets 13 and 20 assembled by lateral cleats 15 (but they could as well be transverse).

The sheet 20 is perforated and has functional orifices 21 for various fasteners to be used later. It is stiffened by a reinforcing profile 14, 17 integral with the sheet 13.

The cleats comprise here openings 16 and the reinforcement profile 14, 17, openings 19 to facilitate the injection operations of the foam A in a hollow body 18 having difficult to access surfaces to protect.

To take only the example of the floor structure 10, where it was necessary to provide, after manufacture of the structure 10 and before laying the wooden floor 11 on the metal frame 12, steps of application of primary paint anticorrosion, soundproofing, rubber bands and cleats, rock wool between the cleats, a single injection step of the product A, B will suffice now.

It will be noted that it is also possible to use the above protective treatment method to protect electrical cables as they pass through the hollow body 18. Foamed foam is used to envelop them and thus to form a sheath. protection, especially against fire.

The ordinary maintenance of the wagons to include regular cleaning operations, it may happen that infiltrations of water and detergents resulting from successive cleanings degrade such or such part 22, as drawn in dotted line on the figure 2 of the metal structure 10 to require repair, for example during so-called mid-life operations.

If the metal structure 10 is constructed according to the above construction method, the deteriorated portion 23 of the torch portion 22 may be cut without having to disassemble the wooden floor portions 11, or any flammable element located nearby, or seats, carpet resting on this floor. Indeed, the cellular foam A expanded in the hollow body 18 to protect it is interposed between the part 23 to be replaced and the floor 11, and, separating it from the part 23, insulates it thermally and protects it from the fire.

It is then only necessary to proceed to the manufacture of the new part 23 and its welding to the part 22, then, the replacement being completed, to apply the anti-corrosion protection of the new hard-to-reach surfaces of the replaced part 23 according to the above protection method. As the cellular foam thus acts as a non-flammable thermal barrier, the part 23 can be replaced by welding without dismounting the flammable element 11.

Claims (7)

1. Method for maintenance of a metal structure (12) of railway cars, comprising an inflammable element situated close to or resting on the structure (12), by replacing of a part (23) of the structure (12), the structure further comprising at least one hollow body (18) and the part (23) to be replaced,
   the method including:

   - at least one step of injecting a cellular foam carrying an anti-corrosion agent and a fire retardant or a thermal insulator (3), into the hollow body, the cellular foam being a non-inflammable thermal barrier (11) of the structure part (23) to be replaced, and

   - a step of directly replacing said structure part (23) without prior removal of said inflammable element (11), wherein said structure part (23) is flame cut and replaced with another part which is welded to the structure (12).
2. Method of maintenance according to claim 1, wherein a mixture of a first component (B) for the expansion of a second component (A) carrying the anti-corrosion agent is injected in order to produce the anti-corrosion cellular foam.
3. Method according either claim 1 or claim 2, wherein the cellular foam (A) includes adhesion pigments.
4. Method according to any of claims 1 to 3, wherein the cellular foam (A) carriers an acoustic insulator.
5. Method according to any of claims 1 to 4, wherein the cellular foam (A) carriers an impermeable resilient agent.
6. Method according to any of claims 1 to 5, wherein the cellular 5 foam (A) includes a filling product.
7. Method according to claim 6, wherein the filling product is hemp.

Images