JPS5944555B2 - Lining pipe with excellent rust and corrosion resistance - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a lined steel pipe or a lined cast iron pipe that has excellent rust and corrosion resistance over a long period of time as a water supply steel pipe for water supply, sewage water, or seawater. An emulsion mixture of ethylene-vinyl acetate copolymer, in which a large amount of emulsion hydrate is produced by adding It is something to do.

Currently, when steel pipes and cast iron pipes are used to transport water and sewage water and seawater, cement mortar is used to increase the rust and corrosion prevention effect inside the steel pipes and cast iron pipes, depending on the usage conditions and applications. Those with lining processing are used.

However, steel pipes, cast iron pipes, and Portland cement mortar linings not only expand and contract differently due to temperature differences, but also undergo strain and pressure due to soil pressure when buried underground, resulting in changes in the inner diameter and cracks in the Portland cement mortar lining layer. The current situation is that the rust and corrosion prevention effects are significantly reduced, and even accidents can occur.

The inventor of the present invention has conducted intensive studies to correct the drawbacks in the rust prevention and corrosion prevention effects of conventional mortar-lined steel pipes or cast iron pipes used as water pipes, and based on the fact that steel materials are not corroded by alkaline solutions, This idea was started from the idea that rust could be prevented by bringing pipes to a state similar to that of minerals, which is the state before they are manufactured as steel pipes or cast iron pipes.

Natural iron forms a stable mineral by combining with oxygen, sulfur, water, silicic acid, etc.

We also know that if oxygen is not dissolved in liquid water, hydrogen polarization will occur, and if the water is saturated with ferrous hydroxide, corrosion of iron will be inhibited.

I also understand that when an alkali is added to liquid water, ferrous hydroxide, which is produced by a reaction with hydroxyl groups, becomes insoluble, and the steel surface does not corrode.

The reason why the form of corrosion is not determined by ionization tendency or electrode potential is because the nature of the compounds formed on the surface is more decisive.

Additionally, polyvalent metal salts of high molecular weight fatty acids (e.g. AL
It has been confirmed that salts such as Ca1, Zn) and ammonium salts have excellent rust-preventing effects on steel materials, and that AL salts in particular have excellent rust-preventing effects on salt water. This is because the interface with the steel surface is always alkaline and there is a strong tendency to form ferrous hydroxide in water.

Therefore, the present invention does not simply form a mortar lining layer on the inner and outer surfaces of conventional steel pipes and cast iron pipes as a rust-preventing and anti-corrosion layer (such as ethylene-vinyl acetate emulsion, which has a high water absorption rate when dried to form a film). A coating film of an emulsion mixture is used as a binder and a cellulose derivative substance or alumina cement is added to produce a large amount of emulsion hydrate on the inner and outer surfaces of steel pipes or cast iron pipes. The objective is to make the interface between the inner and outer surfaces and the paint film alkaline, coat the inner and outer surfaces with aluminum salt, silicate, calcium salt, and acetate, and apply a cement mortar lining over the coating. .

In short, the present invention focuses on the fact that an ethylene-vinyl acetate emulsion film swells and breathes when it contains water. Use high alumina cement together with aggregates such as bentonite, silica sand, and aluminum oxide powder to form an emulsion rust-proofing and anti-corrosion film layer before applying cement mortar lining to the inner and outer surfaces of steel pipes and cast iron pipes. It is characterized by

As a result, even if the mortar lining layer of the steel pipe or cast iron pipe cracks or the cracked part falls off and the emulsion film comes into contact with water, the bones such as alumina cement and bentonite mixed in the emulsion film formed on the pipe can be removed. Due to the breathing action of the flexible, breathable polymer coating that surrounds the material particles, admixtures such as aluminum, silicon, and calcium are constantly released from this coating through microfluidization, forming aluminum salts, silicates, It produces calcium salts, acetates, etc., which are useful for sealing cracks, and this can prevent corrosion of steel pipes due to water intrusion through the cracks.

This is based on the idea that the free energy corresponding to the ionic state in the emulsion is in equilibrium, and the change in free energy is O.Also, by always making the iron surface alkaline, corrosion of the iron is prevented, and it is also It also protects against drugs.

However, this emulsion mixture has various properties such as not only dry and wet adhesive strength with steel pipes or cast iron pipes and corrosion resistance, but also elasticity, abrasion resistance, heat and cold resistance, ozone resistance, and chemical resistance. It goes without saying that it should be done.

In the present invention, the emulsion that is the base for making the emulsion mixture as a rust prevention and corrosion prevention layer has water absorption, water retention,
It is made of ethylene-vinyl acetate copolymer because of its excellent swelling effect, especially alkali resistance and swelling rate.

Next, in the formation of the emulsion film, cellulose derivatives such as hydroxyethylcellulose, ethylhydroxyethylcellulose, and aminoethylcellulose are used to increase the efficiency of water absorption and water retention and to form a thick film, which improves the drying effect and stabilizes the film. Alumina cement is used to maintain properties, bentonite is used to promote water absorption and swelling, and aggregates such as silica sand or aluminum oxide powder are used to increase adhesive strength with steel pipes and cast iron pipe surfaces.

In the present invention, the range of use of the cellulose derivative substance and the inorganic substance in the emulsion when preparing the emulsion mixture that becomes the rust-preventing and anti-corrosion coating layer is preferably 0.1 to 5 parts by weight of the cellulose derivative substance per 100 parts by weight of the emulsion.
Parts by weight, 20-50 parts by weight of alumina cement, 0.1-5 parts by weight of bentonite, 10-5 parts by weight of silica sand or aluminum oxide powder
The amount of alumina cement used is particularly important in the present invention.

In other words, alumina cement is normally used as the original cement for cold-resistant construction or high-temperature deterioration construction, and in this case, 10% alumina cement is mixed with about 30% water.
It is used at about 0%.

However, in the present invention, the amount to be used is completely different from such an amount, and the amount to be used is equal to or less than the amount of water in the emulsion. Therefore, the amount to be used is as described above for an emulsion having a concentration of 50% or less.

This is aluminum, which is a component of alumina cement.
This is because the purpose is to melt silicon, calcium, etc. as the emulsion film breathes water.

However, when the ethylene-vinyl acetate emulsion mixed with the cellulose fibers of the present invention and aggregates such as alumina cement and bentonite is applied to a steel pipe or cast iron pipe and dried, the adhesive strength between the film and the pipe interface is 30 to 40 kg/ It is c4.

After drying the emulsion film on the steel pipe and cast iron pipe constructed in this way, it is lined with Portland cement to obtain a lined steel pipe. By using a mixture mixed with a diluted aqueous solution, chlorine resistance and adhesive strength can be significantly increased.

The adhesive strength between the film and the Portland cement lining layer is 10 to 20 kg/crr7 or more in dry and wet conditions.

However, after applying the emulsion to such steel pipes and cast iron pipes, lining can be applied to both the inner and outer surfaces of the steel pipes and cast iron pipes, and lining can be applied to both the inner and outer surfaces of the steel pipes and cast iron pipes. Corrosion of the pipe due to cracking or falling off of the mortar lining layer due to impact, etc., can be sufficiently avoided, and the practical effects of the present invention are extremely large.

However, this can also be applied to other metal surfaces.

Claims (1)

[Claims] 1. Ethylene containing a cellulose derivative and alumina cement to form a large amount of emulsion hydrate.
A lined pipe with excellent rust and corrosion resistance, which is obtained by applying an emulsion mixture of vinyl acetate copolymer to the inner and outer surfaces of a steel pipe or cast iron pipe, and then applying a cement mortar lining process.