JPS624341B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a construction method for forming a highly acid-resistant glass lining on the surface of containers, pipes, etc. made of iron-based oxidizing materials.

As is well known, in the chemical and petrochemical industries that handle acidic substances, containers and pipes made of iron or the like with various linings are used. The acid resistance and corrosion resistance of these containers, etc., as well as the quality of their manufacturing methods, have a significant impact on safety and economy, and are considered important research topics in the industry. Under this situation,
Conventionally, many glass lining construction methods have been adopted for the above-mentioned lining.

However, in these conventional techniques, for example, for iron pipe materials, a glass tube that has already been formed is inserted into the inner hole of the iron pipe material, which is the surface to be lined, and then heated and softened at a predetermined temperature, and welded under pressure from the inside. According to this method, it is necessary to manufacture the glass tube used as the raw material for lining in advance, which requires an enormous amount of manufacturing time. Moreover, there are problems such as the lined glass tube easily peeling off from the iron pipe material. was occurring. In addition, it is difficult to attach glass plates to iron containers with large cross-sections, so
Apply glass lining raw material made into slurry,
After that, a construction method of firing and welding is adopted.
However, this is a so-called frit construction method, in which clay is mixed into the glass lining material to make it easier to apply.
Therefore, since it contains clay, it has poor acid resistance.
This caused various problems.

Here, the component composition in the conventional frit construction method is as follows.

(Component name) (Weight) Fritz 100gr Urea 0.3gr Potassium chloride 0.3gr Clay 3gr Silica powder 15gr Water 50cc The test results of the lining material based on the above component composition were compared with the test results of specific examples of the present invention. I will write about it later as soon as possible.

The present invention was created in view of these problems, and provides a highly acid-resistant and corrosion-resistant lining to the surface of oxidizable iron metals, thereby dramatically extending their service life. The purpose of this lining is to simplify the process and make it easy to install the lining, and its features are as follows:
Silica powder, hydrated borax, nitrous acid, and water are stirred and mixed into powdered glass to form a slurry-like lining material.The lining material is applied to the surface of the member to be lined, and then fired at high temperature in a firing furnace to form the lining. In a glass lining construction method in which raw material is welded to the surface of the lined member, the lining raw material is made into a slurry without containing clay, and the lining raw material is applied to the surface of the ferrous metal lined member by blowing compressed air. It is at the point where it was spray applied through.

Examples of the present invention will be described in detail below according to the drawings.
Examples of the parts to be lined include pipe materials made of cast iron (including reducers, cheeses, elbows, lap joints, both ends of steel pipes, etc.), and containers used for acid systems other than hydrofluoric acid systems and alkaline systems. In addition, various iron-based metals similar to these can be mentioned.

On the other hand, the lining raw material is mainly composed of glass powder mixed with silica powder, hydrated borax, sodium nitrite, and water, and this mixed material is mixed and agitated in a ball mill and ground into a slurry. It has a viscosity that allows it to be applied to a member to be lined.

Here, the preferred distribution of the above-mentioned lining raw material is as follows.

(Ingredient Names) (Weight) 1 Glass powder 500gr (fine powder than 200 mesh) 2 Silica powder 90-100gr 3 Hydrated borax 2-3gr 4 Sodium nitrite 1-2gr 5 Water 160-250cc Also, preferred composition of the above glass powder This can be written as follows.

(Oxide product name) (wt%) 1 SiO ₂ 70-75% 2 Al ₂ O ₃ 1.5-3.5% 3 B ₂ O ₃ 0.2-1.0% 4 MgO + CaO 5-11% 5 R ₂ O 13-22% Above values In this case, if the glass powder particles become coarser than 200 meshes, pinholes are likely to occur in the glass lining. In addition, if each component of the lining raw material such as silica powder is below the above values, cracks will occur when the lining material hardens.
On the other hand, if it exceeds the above-mentioned value, a phenomenon occurs in which the lining member is difficult to peel off from the member to be lined.

The thermal expansion coefficient ratio of glass powder to the lined member is generally 0.5 to 1, for example, if iron is 1.
Although it is said to be about 2.0, in the present invention, a value of 13% or less is appropriate, and if the expansion coefficient ratio becomes larger than this, cracking or peeling will occur when the lining member is cured.

Next, the experimental results when the specific numerical values of the glass powder were set as follows within the above-mentioned preferred numerical ranges will be described below.

[Specific composition of glass powder]

(Oxide product name) (wt%) 1 SiO ₂ 71.5% 2 Al ₂ O ₃ 2.5% 3 B ₂ O ₃ 0.5% 4 MgO + CaO 8.5% 5 R ₂ O 17.0% Based on the above component composition, an example is shown in Figure 1. This figure shows the process of installing glass lining on a lap joint. In the figure, the member to be lined is first stamped and forged from raw materials, then machined. After material and dimensional inspection of this intermediate product, hydrogen and oil are removed from the material, and annealed at about 1100°C to prevent oxidation. , scale removal is performed by sandplast.

Then, the lining material is uniformly sprayed onto the surface of the member to be lined using compressed air from a compressor or the like while rotating the member to be lined, and once placed in an atmosphere of about 100°C in an electric drying oven. Let dry. The dried lining material is visually inspected for pinholes, etc., and if any defects are found, they are repaired. Thereafter, the temperature is gradually increased to 1030° C. in the firing furnace 1 for firing, and the lining raw material is welded to the surface of the lining member. After the cooling process, the lining thickness is inspected to see if it is within the specified thickness (0.4 to 0.6 mm), as well as a 20,000V pinhole test, heat resistance, corrosion resistance, mechanical impact tests, etc. , considered the final product.

Referring to FIGS. 2 to 4, the firing furnace 1 has first, second and second furnaces made of refractory bricks arranged in a row.
It is composed of third baking chambers 2, 3, and 4, and a belt conveyor 5 that passes through each of these chambers, and each chamber is provided with a heater 6, and each heater 6 follows the direction in which the mesh belt 7 of the belt conveyor 5 moves. The temperature is set to increase gradually. Specifically, the heater 6 is heated to 200°C and 400°C in the first room (2), and heated to 200°C and 400°C in the second room (3).
The temperatures are set at 600°C and 800°C in the third room (4), and 950°C and 1100°C, respectively. And mesh belt 7
The moving speed of the mesh belt 7 and the temperature of the heater 6 are all variable and adjustable, and the speed of the mesh belt 7 is 50 to 120 mm/min.
It is forced to move.

In the above example, the final temperature of the heater 6 is 1100.
℃, but since the welding of the lining material is approximately completed at 950°C, a higher temperature may be selected as appropriate depending on the composition of the lining material.

The test results based on the above specific examples are as follows.

() Pinhole test Measured at 20000V with short circuit voltage 2.3mA,
As a result, there are no abnormalities.

() Heat resistance test The lining material was raised to 300℃ in a firing furnace, rapidly cooled in 20℃ water, and inspected for pinholes and other defects using a spark tester at a short circuit voltage of 2.3mA and 20,000V, but no abnormalities were found. do not have.

On the other hand, when the frit-based lining material was rapidly cooled in water from 200°C to 20°C, it cracked because it contained clay in its component composition.

() Corrosion resistance test This is a mass reduction acid resistance test method specified in JIS R4201, in which the test material was boiled in 20% hydrochloric acid for 24 hours.

As a result, the amount was 0.025 mg/cm ² /24 hr in both the liquid phase and gas phase.

On the other hand, the results of the same test for the lining material using frits were 0.1 mg/cm ² /24 h in the liquid phase and 0.21 mg/cm ² /24 h in the gas phase, and a remarkable difference was observed between the two.

() Impact test The test was carried out as shown in Figure 5, with a 60 mm thick, 0.5 m wide, and long
Place a 2m surface plate 9, and place a 6mm thick plate on the surface plate 9.
Test piece 10 with a 0.6 mm glass lining on the bottom surface was placed on a 10 cm square iron plate, and the weight was measured.
A 300 gr steel ball 11 was allowed to fall naturally onto the test piece 10 from 2 m above through the guide tube 12 five times.

The pinhole test was performed every time, but no abnormality was found.

In addition, when the test piece 10 is a steel pipe lined with a lining, as shown in FIG.
Test piece 10 is an SGP glass steel tube with a length of 100mm.
It was placed horizontally on the surface plate 9 and tested in the same manner as above. Test piece 10
The lining material thickness is 0.53mm for 25A, 0.62mm for 40A, 0.6mm for 50A, and 1.06mm for 80A.
There were four types, and there were no abnormalities in all of them.

According to the present invention, since the lining raw material is generated without containing clay, it has achieved a dramatic improvement in acid resistance and corrosion resistance compared to the conventional frit construction method that contains clay, and has extended its service life. As for the construction of the lining, the labor involved in manufacturing the glass tubes and glass plates was simplified, and the problem of the lining member peeling off from the lined member was also avoided, making it a highly useful invention. It is. or,
Since the lining material is applied by spraying, the lining thickness is uniform and the finish is smooth.
It is considered to be a highly effective invention.

[Brief explanation of the drawing]

The figures show embodiments of the present invention; Fig. 1 is a construction process diagram of the present invention; Fig. 2 is an overall perspective view of a firing furnace;
The figure is a plan view of the same, FIG. 4 is a view taken along the line AA in FIG. 3, and FIG. 5 is an explanatory diagram of the impact test.

Claims (1)

[Claims] 1 Stir and mix silica powder, hydrated borax, nitrous acid, and water into powdered glass to form a slurry-like lining material, apply the lining material to the surface of the member to be lined, and then fire it at a high temperature in a firing furnace. In a glass lining construction method in which the lining raw material is welded to the surface of the lined member, the lining raw material is made into a slurry without containing clay, and the lining raw material is applied to the surface of the ferrous metal lined member using compressed air. A method for constructing a glass lining, characterized in that the glass lining is applied by spraying.