JPS59150579A - Heavy corrosion-preventing coating method for equipment - Google Patents

Abstract

PURPOSE:To inhibit the penetration of oils into a coating film, by mist coating the coating film of zinc-rich paint formed by undercoating with paint usable as an intermediate or finish coat, in advance of a working step. CONSTITUTION:A workpiece to be coated formed into equipment to some extent, e.g. the frame of a stator for the power generator of a steam turbine, is shot blasted, and then inorganic zinc-rich paint is immediately applied to thickness of 50-100mum onto the workpiece to be coated. After the lapse of an interval of 24hr, epoxy intermediate or finish coat paint diluted by adding a solvent for exclusive use to it is applied by mist coating. Then, the workpiece is handled in a working step, i.e. machining, assembling and experimental driving. Since the workpiece is large-sized equipment, it is handled in a decomposing step. In addition, the workpiece is roughened with sand paper #60 and then washed with a solvent.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a heavy-duty anti-corrosion coating method for equipment. In particular, it relates to a coating method when applying a heavy anti-corrosion coating using a zinc-rich paint as an undercoat.

Such a coating method is used, for example, for generators, electric motors.

electrical equipment such as transformers, or steam turbines.

It is used as a heavy-duty anti-corrosion coating for machinery such as water turbines and rolling mills.

[Prior art]

Conventional undercoat paints are so-called rust-preventing pigments, such as sotalic acid resin, epoxy resin, or drying oil, mixed with rust-preventing pigments such as lead red (Pbs04) and zinc chromate (K, 0-40rO, -4ZnO-3H,0). Stopper paints have been used. However, recently, heavy-duty anti-corrosion coatings, in which a zinc-rich paint containing a large amount of zinc powder is used as an undercoat and then various types of paints are applied (finishing coats) on top, are being applied not only to equipment installed outdoors, but also to indoor installations such as generators, steam turbines, etc. It is beginning to be applied to water turbines, etc. It can be said that this trend is more prevalent in products exported to foreign countries, but in any case, it is predicted that this coating system will become more common in the future.

As the zinc-rich paint, inorganic zinc-rich paint or organic zinc-rich paint is used. Inorganic zinc-rich paints are composed of, for example, alkali silicate or alkyl silicate, a large amount of zinc dust (Zn), and some color vehicle, and organic zinc-rich paints are composed of, for example, epoxy, chlorinated rubber, etc. It is made up of a large amount of zinc powder and some color vehicle. Further, as the paint to be applied over this, for example, epoxy paint, polyurethane paint, vinyl chloride paint, etc. are used.

By the way, zinc-rich paint exhibits an extremely excellent anti-corrosion effect due to the electrochemical phenomenon caused by zinc, which is based on a principle similar to that of galvanized galvanized iron sheets.

However, on the other hand, since the paint contains a large amount of zinc dust, the formed paint film is inevitably more porous than conventional primer paints, which causes problems in the painting process. There is.

That is, depending on the equipment to be painted, work steps other than the painting process may be required before the painting is completed, such as machining, assembly, partial welding, trial running, etc.; Because of this, the various oils used in this work process inevitably penetrate into the interior of the porous undercoat film. As a result, a top coat coated on top of a coating film impregnated with such oil has poor adhesion, resulting in a coating film with low reliability.

The prior art will be explained as follows with reference to FIG.

Taking the above-mentioned generators and steam turbines as examples, their parts, such as the stator frame and outer casing, are generally first manufactured by forming steel sheets (bending, cutting, welding, etc.) as shown in step ① in Figure 1. Roughly shaped. Thereafter, the surface to be painted is prepared by shot blasting, sandblasting, etc. (Step 2), and the zinc-rich paint is applied (Step 2). After the coating has sufficiently dried, work such as machining, partial welding9 assembly, and, in some cases, test runs are performed. In this work step (2), cutting oil, grease, turbine oil, etc. inevitably adhere to the coating film as a result of the work. Since the undercoat film with zinc-rich paint is porous, these various oils penetrate into the interior of the film. Once the oils have penetrated, it is impossible to remove them even with solvent cleaning. be. For this reason, after work process ■, disassembly process V, cleaning and undercoating (4
) Even if the repair process (2) is performed and a finish coating (process (2) is applied thereon), the adhesion is poor and it is extremely difficult to form a reliable finish coating. The same applies to small equipment that does not require disassembly and is ready for final painting.

As a general solution to this problem, a technique as shown in FIG. 2 has been recommended. This is a method in which, instead of the undercoating step (2) of the zinc-rich paint shown in FIG. 1, a thin film zinc-rich paint is applied (step (2)) after the shot blasting or sandblasting step (2). This thin-film zinc-rich paint is generally called shop primer, and while a coating film of about 50μ is formed in the first @ undercoating step (■), when this shop primer is used, a thin film is formed. obtain. Therefore, in the shop primer application step (2), approximately 15 to 20 microns of this is applied. After that, work steps (2) such as machining and tying up are carried out, and large equipment is disassembled as necessary (step (v)), followed by step (v') in which the applied shop brimer is removed using Sweetplast or a power tool. It is.

Thereafter, cleaning is carried out as necessary (step 2'), and step 2a is started in which a zinc-rich paint for undercoating is applied. After that, it passes through a mist coat (step ■b) and enters the finishing painting step ■.

According to the method described above, by applying the shop primer, a temporary undercoat effect can be obtained, and various work can be done during this time, and the thin film of the shop primer that has penetrated with oil etc. is mechanically removed, so the subsequent undercoat and topcoat can be applied. ■ can be done appropriately. However, according to this method, it takes a very long time to remove the shop brimers, which increases the number of man-hours and is extremely uneconomical.

Moreover, in this removal step v', a large amount of fine dust containing a large amount of fine zinc powder and other various substances is generated. Such fine dust accumulates inside the factory and becomes a hindrance to the manufacturing process, and requires time and effort to remove and clean the dust, which is not only a problem for papermaking but also for occupational health and the environment. This method is recommended by paint manufacturers, and it is not necessarily clear whether it is publicly known or not.
Either way, it's not a very good solution.

[Purpose of the invention]

The purpose of the present invention is to solve the above-mentioned problems, to achieve coating on a zinc-rich paint undercoat film with good adhesion and high reliability, and to be economical without increasing the number of man-hours and time. The purpose of the present invention is to provide a heavy-duty anti-corrosion coating method for equipment.

[Summary of the invention]

To achieve the above purpose, cutting oil during machining, etc. is applied to the coat of primed zinc-rich paint.

It is sufficient to adopt a structure that can form a coating film that prevents penetration of various oils during work processes, such as grease for rust prevention during processes, and turbine oil during assembly or trial operation.

The present inventor focused on this point, and as a result of various studies to see if it was possible to form a zinc-rich paint undercoat film as described above,
This led to the present invention.

The heavy corrosion protection coating method of the present invention can be used as an intermediate coat or top coat on the zinc-rich paint film formed by the undercoat before the work process is performed after undercoating and before the completion of painting. It is characterized by a mist coat of paint.

In this way, the mist coating replaces the air bubbles in the fine pores of the zinc-rich paint undercoat film, thereby preventing oil from impregnating into the paint film.

Generally, mist coating is carried out using a technique such as that shown in FIG. 2, in which the top coating is diluted with a solvent and then applied in the form of a mist just before the top coating. This is done to replace the air bubbles in the zinc-rich paint film by applying a mist coat before the top coat, and to make the top coat reliable and reliable.

Such mist coating is performed immediately before topcoating (however, at necessary intervals), and is considered to be a pretreatment for topcoating. Because the concept of topcoating is fixed in this way, applying this mist coat at a time other than immediately before topcoating has never been thought of before.

The reason why paint manufacturers recommend the method shown in Figure 2 is because they firmly believe that mist coating is for topcoating.In fact, it is common knowledge among experts that they should change the timing of mist coating. Such factors were not taken into account at all, and on the contrary, it seems to be the case that the well-known technique of using a shop primer was adopted.

However, as shown in the table, the inventor of the present invention broke away from such fixed ideas in the art industry and adopted the process described above, thereby achieving high adhesiveness and reliability of the topcoat, and requiring no process or time. This led to the development of a heavy-duty anti-corrosion coating method for equipment that can be achieved with easy operation.

[Embodiments of the invention]

An embodiment of the present invention will be described below. In this example, the present invention is applied to a case where an inorganic zinc-rich paint is used as an undercoat.

As shown in Figure 3, this painting method involves mist-coating a paint that can be used as an intermediate coat or undercoat onto the zinc-rich paint film formed in the undercoating process (■) prior to the work process (■). Step 1 [a is performed.

Adopting this process prevents oils from penetrating into the inorganic zinc-rich paint film during the work process, eliminating the need for removing the paint film or repainting, and reducing work time. It is also significantly advantageous in terms of cost.

Details of this embodiment are as follows. An object to be coated that has been previously formed to a certain degree (1), such as a stator frame for a steam turbine generator, is shot-blasted, and immediately after the shot-blasting step (2), an inorganic zinc-rich paint is applied to the object and an undercoat is applied. In this undercoating step (2), in this example, inorganic zinc rich paint is applied at a concentration of 50 to 100%.
Apply to a thickness of μ using an airless spray gun. Next, at intervals of about 24 hours, a paint that can be used as a top coat or undercoat, such as an epoxy top coat or intermediate coat, diluted by adding a special solvent, is applied (mist coating) using an air spray gun (process 111
a). In this example, 50 g of a special solvent was added to dilute it, but it is sufficient to dilute it to the extent that it can penetrate into the fine pores of the undercoat film and replace it with air. In this case, the mist coating was applied in a range of 20 to 30 μm. As a result of this mist coating step 1 [[a], the air within the pores is completely replaced by this.

After this, we enter the work process ①, which includes machining and assembly.

A trial run is carried out, and in the case of the example above, since it is a large device, it goes through the disassembly process (■). Next, the surface is roughened with ÷60 sandpaper and further cleaned with a solvent (Step 2). Next, in the case of carrying out the top coating step (2), which is the final coating, 50 to 100 microns of epoxy top coating is applied using an airless spray gun.

Note that the epoxy top coat may be applied at the site after installation is completed, rather than after disassembly and before assembly as in this example.

According to this embodiment, a mist coating with epoxy paint (process IIIa) is performed before work process (2) such as machining and assembly.
This prevents the oils from penetrating the undercoat zinc-rich paint film during the work step (2). In other words, oils such as cutting oil during machining, anti-corrosion grease during step (11), and turbine oil during assembly and trial operation permeate the zinc-rich coating and disappear. Therefore, as shown in the example in Figure 1, the adhesion of the top coat is poor,
The problem of lack of reliability is solved. Then, remove the shop primer and repaint as shown in the example in Figure 2, that is, apply shop primer ■', remove the resulting zinc-rich coating using sweep blasting or power tools, and then repaint. There is no need to do anything. Of course, there is no generation of large amounts of fine dust.

In this example, we simply mist-coated epoxy, vinyl,
The surface of a thin film of paint such as polyurethane can be cleaned with a solvent, roughened with sand vapor, and then topcoated. Therefore, it is possible to significantly reduce the number of man-hours. In addition, it is good in terms of hygiene and working environment, and since it can be completely degreased, the adhesion of the top coat is extremely good.
It also has great effects in terms of performance and reliability.

〔Effect of the invention〕

As mentioned above, the heavy-duty anticorrosive coating method of the present invention has the effect of achieving good adhesion when applied to the Gin (12) Flitch Paint undercoat film, and extremely reliable coating. Moreover, this does not increase the number of man-hours and time; in fact, there is no need to remove the paint film or repaint, so the number of man-hours and time can be reduced, and significant time can be saved.

It is extremely advantageous both in terms of work and economy. This has the effect that there are no problems in terms of working environment or hygiene.

It should be noted that, as a matter of course, the present invention is not limited to the specific steps described above.

[Brief explanation of the drawing]

FIGS. 1 and 2 are process diagrams showing the prior art. Third
The figure is a process diagram showing one embodiment of the present invention. ■...Zinc rich paint undercoat process, ■a...Best coat process, ■...Work process. Agent Patent Attorney Masami Akimoto (13) 1st and 2nd Patent Publications 1987-150579 (5)

Claims (1)

[Claims] 1. In the case of applying a heavy anti-corrosion coating with an inorganic zinc-rich paint or an organic zinc-rich paint as an undercoat to equipment to be painted that requires a work process other than the painting process before the completion of painting after undercoating, the work process described above is applied. in front of,
A heavy-duty anticorrosion coating method for equipment, comprising: mist-coating a paint that can be used as an intermediate coat or top coat on the zinc-rich paint film formed by the undercoat.