JPH0375305B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] "Industrial Application Field" The present invention relates to a method for removing deposits adhering to the inner surface of a pipe using a compressed fluid mixed with an abrasive.

``Conventional technology'' The conventional method for cleaning inside pipes is
There is an invention disclosed in Publication No. 41852. Simply put, this method cleans the inside of piping by mixing abrasive material with high-pressure air and passing it through the piping, much like sandblasting. This conventional invention is for cleaning straight pipes. Next, the invention disclosed in Japanese Unexamined Patent Publication No. 56-91881 is a method for cleaning the inside of a regi-use piping, which also cleans a straight pipe.

By applying this technology for straight pipes, bent pipes are cleaned in the same way. This method aims to clean the entire circumference of a bent pipe by selecting one type of abrasive with an appropriate particle size depending on the condition of the deposits inside the pipe, mixing it with the airflow, and passing it through the inside of the bent pipe.

"Problems to be Solved by the Invention" Conventionally, in this type of equipment, one type of abrasive material with an appropriate particle size was selected and used depending on the situation of the deposits inside the pipe, but it is difficult to use an abrasive material with a relatively coarse particle size. The abrasive particles are deflected and flow toward the outer diameter side of the curved tube section due to inertial force and centrifugal force in the curved tube section, resulting in a drawback that removal of deposits on the inner diameter side of the curved tube section is difficult. This also creates the risk that the coating on the residual deposits will peel off during lining.

The present invention eliminates the above-mentioned drawbacks in the method of cleaning a bent pipe section with compressed gas mixed with an abrasive,
It is an object of the present invention to provide a method for efficiently removing deposits on the inner diameter side of a bent pipe portion.

[Structure of the invention]

``Means for Solving the Problems'' The present invention provides a method for removing deposits in a pipe by flowing compressed gas mixed with an abrasive through a pipe having a bent pipe section. This is a method for polishing a curved tube section, characterized in that deposits on the curved tube section are efficiently removed by mixing.

"Function" Coarse-grained abrasives mainly remove deposits on the outer wall of the bent tube, while fine-grained abrasives collect on the inner side of the bent tube due to the secondary flow of the bent tube. Deposits on the inner diameter side of the tube are removed.

“Examples” Examples of the present invention will be described below with reference to the drawings. FIG. 1 is a side view showing the flow of fluid in the bent pipe section, and FIG. 2 is a sectional view taken along line XX in FIG. 1.
The flow of the compressed gas mixed with the abrasive material passing through the bent pipe section 1 bent at various angles in the piping is indicated by arrows.

In the present invention, a mixed abrasive material consisting of two components, coarse grains and fine grains, is used as the abrasive material. The mold polishing material, which is a mixture of coarse particles and fine particles, is mixed with compressed air and blown into the bent pipe section 1 in the direction of arrow 2, as shown in FIG.

If the abrasive material contained in the compressed gas entering from the direction of arrow 2 is coarse particles, it will be deflected toward the outer diameter side due to inertial force and centrifugal force in bent tube section 1, resulting in a trajectory like arrow A in the figure, resulting in bending. It does not contribute to the removal of deposits 4 occurring on the downstream side of the inner diameter side 3 of the pipe portion 1.
If the abrasive material contained in the compressed gas entering from the direction of the arrow 2 is a thin stream, the curved pipe portion 1 has an outer diameter side 6 and an inner diameter of the bent pipe portion 1 as shown by the streamline 5 marked with an arrow in Fig. 2. Under the influence of the secondary flow due to the pressure difference between the sides 3, the flow along the tube wall from the outer diameter side 6 to the inner diameter side 3 of the streamline 5 collects on the inner diameter side 3 when passing through the bent pipe section 1. Therefore, as shown by arrow B in FIG. 1, the fluid flows through the inner surface of the tube toward the inner diameter side 3 to remove deposits 4 on the inner diameter side 3. Fine-grained abrasives have a small momentum per particle, but when mixed in large quantities, the same polishing effect as coarse-grained abrasives can be obtained.

Example 1 Coarse abrasive material types: Crushed stone, silica sand Same as above Abrasive material Average particle size: 2 to 5 mm depending on pipe diameter, average diameter 3 mm if below 80A Fine abrasive material types: Silica sand, black haze Same as above Abrasive material Average particle size 1.0 to 2.0 mm where the momentum per particle is not too small due to the action of secondary flow Coarse and fine particle mixing ratio Basically, the 1:1 range is (40 to 60 mm) so that the total momentum is equal. %).

Compressed fluid Air Compressed air source pressure 7Kgf/cm ² G Compressed air flow rate Average 80m/s Pipe diameter Available in various sizes from 13A to 200A Average bending radius of bent pipe portion Available in various sizes from 13A to 200A Bend angle of bent pipe portion 90 degrees No deposits 4 Component Iron hydroxide It was confirmed that the deposits 4 on the bent pipe section 1 were completely removed by this Example 1. However, the deposits 4 were not sufficiently removed by using only the coarse abrasive material.

〔Effect of the invention〕

The present invention is a method for removing deposits in a pipe by flowing compressed gas mixed with an abrasive through the pipe having a bent pipe, and in which the deposits in the pipe are removed by mixing abrasives with different particle sizes. Since this method of polishing a curved tube portion is characterized by efficiently removing the particles, it is possible to effectively remove deposits on the inner diameter side of the curved tube portion, which have been incomplete in the past.

In addition, since the deposits on the bent pipe are completely removed in the polishing process, a uniform lining film can be obtained in the lining process, and the peeling of the film due to residual deposits will not occur, which will extend the service life of the pipe rehabilitation method. and certain quality functions can be obtained.

[Brief explanation of drawings]

FIG. 1 is a side view showing the flow of fluid in the bent pipe section, and FIG. 2 is a sectional view showing the flow of fluid at the XX cross section in FIG. 1...Bent pipe part, 2...Arrow, 3...Inner diameter side,
4... Deposit, 5... Streamline, 6... Outer diameter side.

Claims (1)

[Claims] 1 In a method of removing deposits in a pipe by flowing compressed gas mixed with an abrasive through a pipe having a bent pipe, the deposits in the bent pipe are efficiently removed by mixing abrasives with different particle sizes. A method of polishing a bent pipe portion, which is characterized by removing the bent pipe portion.