JPS6157829A - Leakage detecting agent for barometric test - Google Patents

Abstract

PURPOSE:To obtain a leadage detecting agent which does not require a stage for removing the detecting agent after inspection by using an aq. soln. prepd. by contg. both of a surface active agent having excellent foaming power in low concn. and an ammonium salt of carbonic acid which volatilizes in a short period in a specific concn. range as the detecting agent and observing the presence or absence of foaming after coating. CONSTITUTION:The aq. soln. contg. 0.01-0.5wt% surface active agent such as nonyl phenol polyethylene ether having excellent foaming power and stability and 0.05-2wt% ammonium carbonate, ammonium hydrogencarbonate or a mixture composed thereof which volatilizes in a short period is used as the leakage detecting agent for barometric test. Such detecting agent is coated on the surface of a structure such as hull, tank, pressure vessel or piping which requires airtightness and water tightness after compressed air or the like is fed into the structure then the presence or absence of foaming is detected. There is no need for cleaning or wiping away after the detection. The detecting agent volatilizes and dissipates without inducing corrosion and retarding the adhesion of a paint and therefore immediate painting, etc. are possible.

Description

[Detailed Description of the Invention] [Industrial Field of the Invention] The present invention is directed to supplying compressed air or the like into structures that require airtightness or watertightness, such as ship hulls, various tanks, pressure vessels, and piping. The present invention relates to a gas leakage detection agent for detecting gas leakage based on the presence or absence of foaming by completely applying a foaming liquid to a surface, that is, a leakage detection agent for atmospheric pressure testing.

[Prior art]

Conventionally, in this field, various surfactants such as soaps, synthetic detergents, U, alkylbenzene sulfonates, fatty acid ethanolamides, alkylphenol polyoxyethylene ethers, and higher alcohol polyoxyethylene ethers are used as foaming agents, and the To prevent corrosion, a suitable amount of nitrite, phosphate, borate, benzoate, sebacate, etc. is added.

[Disadvantages of the above conventional technology]

However, when these detection agents are used, the surfactants, polymer agents, and inorganic salts contained therein remain in the form of sticky or white precipitates due to evaporation of water after the detection operation. The exterior surfaces of equipment subjected to air pressure tests are usually painted, but if you paint directly without removing these residues, the adhesion of the paint to the metal surface will be significantly impaired, resulting in peeling, discoloration, etc. This not only impairs the aesthetic appearance but also poses a major problem in terms of quality control.

Therefore, the residue of the detection agent is removed, but new problems arise as the object becomes larger.

That is, it is removed by brushing under running water or jet water in ships, tanks, etc., but since rust has already formed during washing, it is necessary to use a saunder, wire brush, etc. to remove rust after removal. The expenses and construction time required for these are one of the obstacles to cost reduction.

[Object of the present invention]

The present invention is a leak detection agent for atmospheric pressure tests that eliminates all the residue that occurs when conventional leak detection agents are applied, thereby reducing work, reducing costs and shortening the construction period, and eliminating rusting accidents. The purpose is to provide That is, an object of the present invention is to provide a leak detection side for air pressure tests that does not require removal of residue after the detection operation and does not impede the adhesion of the coating even if it is painted as is.

[Configuration of the present invention]

In order to achieve the above object, the present invention incorporates a low concentration of surfactant as a total foaming agent and an ammonium salt of carbonic acid as an anticorrosive agent. That is, the present invention provides 0.05 to 2% by weight of ammonium salt of carbonic acid,
This is a leak detection agent for atmospheric pressure tests, characterized in that it consists of a mixed aqueous solution containing 0.01 to 0.05% by weight of a surfactant.

In order to generate foam and obtain stability, it is possible to select any surfactant that has foaming power, but those that exhibit good performance at low concentrations are particularly effective. Of course. Therefore, as the surfactant that can be used in the present invention, any surfactant may be used as long as it has good foaming properties, but particularly preferred is nonylphenol polyethylene ether (ethylene oxide 10 to 20%
lauryl alcohol phosphoryoxyethylene ether (addition of 8 to 16 moles of ethylene oxide) has excellent foaming properties and stability.

These surfactants can be used in the range of α01 to α05 weight. If it exceeds α05% by weight, it will affect the adhesion of the paint, and if it is less than 0.01% by weight, foaming properties and stability will be lacking, resulting in a decrease in detection ability, which is not preferable.

On the other hand, in the present invention, when the ammonium salt of carbonate added as a corrosion inhibitor is applied as a solution to the iron surface, it forms a passivation film on the iron surface and completely vaporizes and volatilizes, leaving no residue. It has the property that it never gets wet. As the ammonium salt of carbonic acid, ammonium carbonate, ammonium hydrogen carbonate, or a carbonate having any degree of neutralization between ammonium carbonate and ammonium hydrogen carbonate can be used. The concentration used can be in the range of 1.05 to 2 parts by weight. Use of more than 2% by weight is unnecessary as it will result in excessive rust prevention. In addition, it takes time for it to volatilize, making it unsuitable for painting within a very short time after detection. Further, if it is less than 0.05% by weight, the rust preventive power will be insufficient, which is not preferable.

In the present invention, a surfactant with excellent foaming power is used at a low concentration, and by adding ammonium carbonate to this, it is applied to the steel surface to be detected and remains even after the water evaporates. It has good rust-preventing properties and does not stain or rust.As a result, it eliminates the need for washing with water, brushing, etc., which were conventionally required for removal, and allows immediate painting work. .

Hereinafter, specific examples of the present invention will be cited as invention products, and comparisons will be made with two conventional detection agents (conventional products A and B). The type of detection agent, test items, and results are shown in the table below.

[Note] *1. *2 (Detectability, rust prevention) For inspection of leakage defects in actual ship tanks, air pressure was applied to a2s kg/cm2k, and welding line 30
Regarding M, the detection side sound shown in the table was sprayed and the foaming detectability was observed. Rust prevention was completely observed for another 10 m of bath welding.

*3 (Paint adhesion) A sandblasted steel plate (70 x 150 x 3) was coated with the detection agent shown on the front, and after air drying for 24 hours, the paint was applied with an airless spray. After 14 days of natural drying, 2X2. I put cello tape on the cut-out eaves that reached the base of 25 gobans, and counted the gobans that remained when I peeled them off. The maximum number of gobans is 25.

*4 (Conventional product A) Conventional product A contains 0.5% by weight of sodium dodecylbenzenesulfonate, 0.5% by weight of sodium nitrite,
The remainder is of water composition.

X5 (Conventional product B) Conventional product B contains 5% by weight of polyoxyethylene alkylphenol ether α and 2% soluble starch.
, 4% by weight, water-soluble acrylic resin 0.2% by weight, gelatin 0.1% by weight, sodium tripolyphosphate Q,! It has a composition of 1 part by weight and the remainder water.

As shown in the table above, the product of the present invention is the conventional product A.

Compared to B, the detectability, rust prevention, and paint adhesion were all good, and in particular, the paint adhesion was greatly improved.

[Effects of the present invention]

As detailed above, the present invention has the following advantages compared to the prior art:
The amount of residual substances is extremely small, and as a result, a remarkable effect is produced that does not cause any damage to the coating film even if it is painted without completely removing it after inspection.

Sub-agent: 1) Akira Sub-agent Ryo Hagi Hara -

Claims (1)

[Claims] A leak detection agent for atmospheric pressure tests, comprising an aqueous mixed solution of 0.05 to 2% by weight of ammonium carbonate and 0.01 to 0.05% by weight of a surfactant.