JPS63296874A - Method for lining inner surface of pipe - Google Patents

Abstract

PURPOSE:To adjust the alkali elution amount at the time of the initial passage of water to a reference value or less, by forming a layer composed of motar prepared by kneading cement containing a specific amount of a Na2O+K2O component, sand and tap water by a centrifugal method to the inner surface of a pipe and, after curing, polishing the cured layer in a wet state. CONSTITUTION:Cement containing 0.2% or less of an R2O-component (Na2O+K2 O) and sand containing 6% or less of an R2O-component (NaO+K2O) are kneaded with tap water to prepare mortar. This mortar is used to form a mortar layer to the inner surface of a pipe by a centrifugal method and, after the mortar is cured, the surface of the mortar layer is polished in a wet state to apply lining to the inner surface of the pipe. It is also pref. to adapt the aforementioned lining method to a pipe having an inner surface to which the lining of mortar is applied according to a usual method. Further, the number of rotations of the pipe due to the centrifugal method is pref. GNO 20 or more.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a method for lining the inner surface of a tube.

[Traditional technique (hote)]

Corrosion-resistant lining is usually applied to the inner surface of cast iron pipes for two purposes, such as water pipes, from the two viewpoints of providing corrosion resistance to the pipe itself and eliminating the effect of rust on water quality. be.

As this lining layer, a mortar lining in which the iron base is made alkali passivated to prevent corrosion is preferably used.

By the way, there is a problem that alkaline components are eluted from the mortar lining during the initial water flow, and in order to suppress the increase in pH of the eluted water, a seal coat material is usually further applied to the surface of the mortar lining.

[Problems with conventional technology]

However, if the quality of the water flowing inside the pipe contains a large amount of free carbonate, such as groundwater, the Sealco-1 material may undergo chemical changes and peel off, and alkaline content may be eluted from this ff1llm surface, causing water to flow through the pipe. This causes an increase in pH.

In other words, while the alkalinity of the mortar is necessary for the iron base in lining cast iron pipes, at the initial stage of water flow,
This had an inconvenient ambivalence regarding the quality of water flowing through it.

[Problems solved by the invention]

In view of the above-mentioned problems, the present invention was made with the aim of providing a method for lining the inner surface of a pipe, which does not require the application of a seal coat and can sufficiently suppress the increase in pH of water quality at the initial stage of water flow. .

[Technology to solve problems]

That is, the tube inner surface lining method of the present invention uses the R2O component (
A mortar made by kneading cement with N, 2.20 + K2O) of 0.2% or less and sand with R2O content (same as above) of 6% or less with tap water is layered on the inner surface of the pipe by a centrifugal method.
The method is characterized in that the surface is polished in a wet state after the mortar hardens.

[Action] The potashity of mortar is mainly C'a ('OH) '2
However, the amount of alkali eluted into the contact water, that is, P
Components that cause an increase in I-1 are easily soluble sodium (Na) and potassium (K) contained in mortar.

Furthermore, these causative substances are relatively light components, and therefore, when lining the inner surface of a pipe by centrifugation, they tend to segregate on the inner surface of the lining layer.

Therefore, when performing mortar lining on the inner surface of a cast iron pipe, use cement or sand that does not contain a small amount of Na, as described above, and polish the inner surface of the lining layer, which is free from segregation of Na and K, after hardening of the lining layer. Most of the alkaline eluted components are removed, and the initial PH increase during water flow can be suppressed without the need for providing the seal coat layer 1. In addition, in the present invention, the R2O component (N a
20 + K 20 ) is 0°2% or less, which means using cement with as little R2O as possible. If cement is more than 0.2%, the It is not possible to achieve a PH value below a predetermined standard.

Furthermore, the same reason as above is why sand with an R2O content of 6% or less is used, and if the R2O content is more than 6%, it becomes impossible to bring the pH value at the initial stage of water flow below a predetermined standard.

Note that the cement mortar lining layer constructed in the present invention has a very low degree of elution of alkaline components into flowing water, so it cannot be used as a cast iron pipe with a mortar lining layer rich in R and O components. The method of the present invention can also be applied to a skeleton using a material.

In this case, the lining layer of the present invention prevents the R2O component from elution.

In addition, in the centrifugal method, if the GNO of the tube is set to 20 or more, sufficient centrifugal force will be applied to the mortar, which will cause Rh
It is convenient because the segregation of o(Na2O+KzO) can be made noticeable.

〔Example〕

A component analysis was conducted for the cement, and an alumina cement having the components shown in the table below as the R2O component was selected.

In addition, the bottom column of the table below shows those from ordinary Portland.

Table 1 As a comparative example, NazO is 3.61%, and K and ○ are 4.04%.
Mountain sand was used.

The above cement and sand were mixed in a ratio of 1=2 to obtain a cement slurry, which was made into 1.00 cm in diameter and 300 cm in length.
A lining layer with a thickness of 3 mm was formed on the inner surface of the cast iron pipe by the centrifugal forming method under the conditions of GNO40 x 2 minutes, followed by curing and hardening, and then a polishing treatment was performed with a Sandheper while sprinkling water on the surface of the lining layer. ~0.6 mm surface layer was ground.

After that, after completely curing and hardening the mortar lining layer, the pipe was filled with tap water and the degree of elution of alkaline content into the water after 20'CX24 hours was examined, and all PH values were within the standard value. 8, 6 or less.

In addition, in the case of using ordinary Portland cement and the sand of the comparative example, the pH value was 9.6, which exceeded the standard value, and could not be used without a seal coat.

Next, a lining layer was further provided on the lining tube obtained in this comparative example using cement and sand not shown in Table 1.2, and when a lining layer was provided in the same manner as described above, the elution of alkali components was suppressed. It was found to be usable.

〔effect〕

As explained above, in this invention, the lining layer is formed from cement and aggregate that do not contain components that easily elute into water, so alkali elution can be suppressed to below the standard value from the initial water flow, and seal coat etc. It can be used directly without any further preparation.

Claims (3)

[Claims] (1) R_2O component (Na_2O+K_2O) is 0.2
% or less of cement and sand with an R_2O component (same as above) of 6% or less, mixed with tap water, a mortar is layered on the inner surface of the pipe by a centrifugal method, and after the mortar hardens, the surface is polished in a wet state. A pipe inner lining method. (2) A method for lining the inner surface of a tube according to claim 1, wherein the inner surface of the tube is previously provided with mortar lining by a conventional method. (3) The tube inner surface lining method according to claim 1 or 2, wherein the tube rotation speed by centrifugation is GNO, 20 or more.