DE3347039A1 - METHOD FOR DETACHING OR. REMOVE PROTECTIVE COATINGS OR COATINGS APPLIED TO SURFACES - Google Patents

Description

Nuclear Research Center Karlsruhe / December 23, 1983

Karlsruhe'.GmbH PLA 8370 Gl / he

ANR Ioo2597

Process for detaching or removing materials applied to surfaces Protective coatings or coverings.

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Description:.

The invention relates to a method for detaching or removing protective coatings applied to surfaces. or toppings.

To protect against damaging influences of any kind, become surfaces such as building surfaces, concrete floors, walkways laid with concrete slabs, surfaces of machines or equipment etc. with protective coatings / provided, harmful influences are to be understood here as those influences that both from aggressive gases or liquids, for example from the ambient air or from aqueous Chemicals as well as non-radioactive or radioactive, adherent contaminations. Over time or during operation, the protective coatings may be subject to mechanical effects and chemical exposure. Organic coatings in particular can age and become partial as a result damaged or soiled with adherent contamination. Such damaged or with inactive substances or protective coatings more or less heavily contaminated with radioactive substances must then be detached or removed from their subsurface with as little residue as possible. this applies especially for radioactively contaminated protective coatings before dismantling or dismantling

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breakdown of decommissioned nuclear facilities.

Up to now, methods such as stripping have been used to remove protective coatings from surfaces. mechanical blasting processes, grinding or flame blasting. But this was particularly effective disadvantageous - and this applies in particular to protective systems contaminated with radioactive substances Measure- that additional action is required because

- the workers from the harmful effects of toxic substances, gases, aerosols and radioactivity (Radiation, incorporation) must be protected,

- the spread of these pollutants into the environment must be reduced to a minimum,

- the workplace conditions must be acceptable,

- there should be as little secondary waste as possible,

- the contamination is not carried over into the structure substrate (e.g. in the case of concrete) allowed.

For example, parts of the plant had to be temporarily shut down up to now.

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In the previously used techniques, these disadvantages are to a greater or lesser extent (ie, they are not all preventable and largely eliminate -au).

The invention is based on the object of creating a simple method with which defective and / or contaminated protective coatings or coverings on surfaces, for example of building structures, machines, systems, equipment, etc., easily and detached or removed from their subsurface without leaving any residue. can be removed. The procedure is said to be effective and, especially in the removal of with radioactive substances contaminated coatings, Bring the least possible impact on staff and the environment. The accumulation of waste volumes is intended be as low as possible, i.e. there should be practically no secondary waste and the total expenditure should be economically justifiable.

The object is achieved by the method according to the invention solved in a surprisingly simple manner in that the coating to be removed or the covering with its exposed side facing away from the surface to be protected is exposed to a cold shock. Advantageously is the coating or the covering with a liquefied, inert gas or with a close to the Boiling temperature supercooled inert gas applied. Nitrogen, for example, is used as the inert gas.

The spontaneous extraction of heat leads to a strong contraction within the coating and as a result from this to a delamination of the subsurface. Depending on the physical properties of the coating they are then separated in more or less large, splinter-shaped pieces, namely either as a result of an adhesion break between the coating and the substrate or an adhesion break in the upper area of the underground.

In the one which can be used for the process according to the invention The cold blasting device can be, for example, a compact, mobile system configured with a insulated storage tank for the refrigerant, a flexible insulated hose line and a jet pipe with exchangeable jet heads, protective sleeves, etc. Through control and regulation devices controlled the refrigerant supply. Due to the mobility of such a system and its compact design use even under "spatially restricted" conditions possible.

By using a cold blasting system, and this is particularly true for highly sensitive areas in nuclear plants, coatings in need of repair and / or contaminated coatings can be applied to simple, Personnel, work rooms and the environment are not detached from their underground structures in a stressful way. Neither solvent vapors nor harmful gases, aerosols or dusts are generated. Furthermore, no

secondary waste, either in solid or in liquid form.

The detached, splinter-shaped coating parts can easily and easily be filled into waste drums and then solidified ready for final storage.

In the following the invention is based on an implementation example explained in more detail. However, the invention is not limited to this example.

Example:

Removal of an epoxy coating due to the action of liquid nitrogen.

Two coated concrete slabs were treated with the following coating structure:

initially about 150 g / m of a green, transparent The inlet base with the company name GEHOPON-EX is allowed to act on the concrete slabs. Thereafter there was a scratch coat to fill in

2 pores and cavities with approx. 350 g / m 2 of a mixture of GEHOPON-E 70 / quartz sand, whereupon the final layer, approx. 1.5 mm thick, with 2.7 kg / m ^{2 of} GEHOPON-E 70 based on epoxy resin, solvent-free and self-leveling. Such a coating

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After it has hardened, it is particularly suitable for Surfaces that need to be decontaminated from radioactive substances. However, the contamination adheres too tight or if the coating is defective, it must be peeled off and replaced. By applying the coated concrete slabs with liquid nitrogen or by allowing it to penetrate the coating and Brief exposure caused cracks in the coating to develop as a result of the cooling, followed by cracks Detachment, with the break occurring in the concrete substrate.

Claims (4)

Nuclear Research Center Karlsruhe, December 23, 1983 Karlsruhe GmbH PLA 8370 Gl / he ANR Ioo2597 patent claims; 1. Process for detaching or removing protective coatings applied to surfaces or Coverings, characterized in that the coating to be removed or the covering exposed to a cold shock with its open side facing away from the surface to be protected will. 2. The method according to claim 1, characterized in that the coating or the covering with a liquefied, inert gas is applied. 3. The method according to claim 1, characterized in that that the coating or the covering with a high inert to the boiling temperature supercooled Gas is applied. 4. The method according to claim 2 or 3, characterized in that that nitrogen is used as the inert gas.