JP2998079B2 - Pig inner surface drying method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a method for forming a lining film such as a resin on the inner surface of an existing pipe by drying after washing in the pipe or by draining a water pressure test by injecting water into the existing pipe. The present invention relates to a method for drying the inner surface of a tube in which drying is performed by a pig.

[0002]

2. Description of the Related Art Iron pipes used in pipelines for natural gas, crude oil, industrial water, clean water, etc., are subject to rust during use for a long time, and the scale inside the pipes due to scales adhering and depositing on the inner surface. Since the fluid is contaminated and the flow is obstructed and the feed rate drops, there is a problem such as a decrease in the feed rate.Therefore, remove the rust and scale, smooth the inner surface of the pipe, and then line the resin etc. to remove the old pipe. Rehabilitation is taking place.

[0003] In addition, pipes through which a fluid having a property of corroding a pipe flows are lined with a resin or the like on the inner surface of the pipe from the time of installing the new pipe to prevent corrosion and rust, thereby extending the life of the pipe. I have to. In this case, it can be implemented immediately after the existing pipe is installed, the construction period is shorter than using painted pipes painted at the factory, the cost is lower, the welded part can be completely painted, the durability is long, etc. This is done because of the benefits.

[0004] In the case of the above-mentioned rehabilitated pipe, first, rust and scale on the inner surface of the pipe are removed with a spike pig, and the pipe is washed with water. The lining is performed, and the drying process is a very important operation because the lining affects the finish unless the drying is completed.

[0005] On the other hand, a water pressure test is also performed by injecting water into an existing pipeline. When the water pressure test is completed, the water must be drained and dried, and in particular, water is drained. A pipe through which an anaerobic fluid such as chlorine gas flows had to be dried to completely remove moisture.

In such a drying operation, usually, a pig of semi-rigid foam in which open cells having a density of about 0.12 g / cm ³ and closed cells are mixed is introduced into a pipe, and air from a compressor is supplied from behind the pig. The spraying pig is moved to dry.

In the case of the pig, even though most of the water in the pipe can be drained, the water film remaining on the pipe wall and the water collected at the bottom of the pipe cannot be absorbed and discharged by passing the pig several times. If the pigs were not passed repeatedly over and over again, they could not be dried, and much time had to be spent on drying.

In order to eliminate such disadvantages, FIGS.
As shown in FIG. 2, a pipe 11 having a gas receiving surface 12 coated with a non-permeable synthetic resin having a specific gravity of more than 1 on one end face of a soft foam having a density of 0.03 g / cm ³ is placed in a pipe P. The pig 15 is moved from the rear of the gas receiving surface 12 by blowing air 15 from the compressor to dry the pig.

[0009]

However, in the case of the pig 11, since the elasticity of the soft foam portion 11a and the synthetic resin coating portion 12a of the gas receiving surface 12 are different, when the pig 11 is inserted into the pipe and transferred, Both are hard to be familiar with,
The joint between the flexible foam portion 11a and the gas receiving surface 12 is easily peeled off, and the flexible foam portion 11a is bent to form a wrinkle 17 or the like.
In addition to lowering the discharging force, the broken wrinkles 17 leaked the gas to be driven, and sometimes caused troubles such as the pig 11 stopping without shifting.

Whether or not the inside of the pipe can be completely dried is not only shortened in the drying step, but also greatly influenced by the selection of a primer in a later step in a lining operation. In other words, it is generally said that it is better to use a vinyl ester primer for the primer if it is sufficiently dried, because of its good adhesion to the base (mainly iron pipe) and good adhesion to the top coat. A series of materials can be used, and the adhesion to the top coat is very good, and a lining with a good finish can be formed.

On the other hand, if moisture remains in the tube, it is necessary to select a type of primer that also reacts with the residual moisture, and it is not possible to select a primer of the same type as that of the vinyl ester resin. A system primer, such as an epoxy urethane primer, will be used.

The epoxy urethane primer is a solvent type, and a thickly applied primer has a low reaction rate at low temperatures, and also has a poor evaporation of the solvent, resulting in a slower curing of the coating film and a forever soft cured product. As a result, there arises a problem that the adhesion to the overcoat paint applied thereon is extremely reduced, and there is a problem that drying must be ensured.

SUMMARY OF THE INVENTION The present invention has been developed to solve the above-mentioned problems, and is used for drying or water pressure test after washing when forming a lining film such as resin on the inner surface of an existing pipe. It is an object of the present invention to provide a method for drying the inner surface of a pipe by using a pig which can achieve drying after draining with certainty and in a short time and can perform efficient drying.

[0014]

Means for Solving the Problems As a means for solving the above-mentioned problems and achieving the object, the present invention has a density of 0.
Before the open cells or closed cells made of a non-permeable foam resin having the same shrinkage and flexibility as the soft foam are polymerized on one end surface of the soft foam of 02 to 0.06 g / cm ^3. of
Break the foam into a paste, 0.05-0.8mm
Characterized in that a pig having a gas receiving surface coated with a thickness of 3 mm is inserted into a tube, and the pig is transferred by dry air having a dew point of 0 ° C. or less to dry the tube inner surface. Developed and adopted.

Here, the term "bubble breaking" refers to a phenomenon in which an open cell changes into a closed cell, a cell is deformed and flattened, or an open cell and a closed cell are broken to form a film. Include.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In FIGS. 1 and 2, 1 is density of pig shell-shaped made of a soft polyurethane foam of 0.02~0.06g / cm ^3, rich absorbent is low density However, since it has an open-cell structure, a gas serving as a driving source passes therethrough. Therefore, a gas receiving surface 2 is formed on one end surface. A soft urethane foam having a density of 0.02 g / cm ³ or less is not suitable because it is soft and absorbs well, but has no holding power and cannot pass smoothly.
The above range is preferable because a soft urethane foam having a weight of 06 g / cm ³ or more becomes slightly hard and has poor absorbability.

On the gas receiving surface 2, the two liquid urethane foaming liquids A and B, which have a long gelling time, are stirred and mixed in a free state. The foamed paste was coated on a soft urethane foam, and the thickness was 0.0
The range of 5 to 0.8 mm is optimal because the same shrinkage and flexibility as the soft urethane foam can be obtained. By this coating operation, as shown in FIG. 3, the cells of the continuous cells were broken or crushed, and just in the thin layer, the closed cells 3 were crushed and broken to form the coating 4. Things overlap and no longer pass gas.

That is, even if the air bubbles change, the air bubbles basically remain, so that the density can be brought close to the soft foam, and the coating portion has the same elasticity and unity as the soft foam. That's it. Since the same material as the soft foam urethane is used as the coating material, the compatibility between the materials is good, and it penetrates into the open cells of the soft foam,
The adhesive force was remarkably improved while closing the open cells.

The pig 1 constructed as described above is connected to the existing pipe P
When the pig 1 is moved by blowing dry air 5 having a dew point of 0 ° C. or less onto the gas receiving surface 2, the outer peripheral surface of the pig 1 is elastically pressed against the inner wall surface of the pipe A and adheres to the inner surface. In addition to absorbing the water film 6, the water film 6 can be dried in combination with the vaporizing effect of the dry air 5 having a dew point of 0 ° C. or less.

[0020]

EXAMPLES Specific examples of the present invention will be described below. 20
Fill the digestion pipe P of 0φ × 300m with water (capacity of about 9420)
kg), and a bullet-shaped pig made of a normal semi-rigid urethane foam having a density of 0.12 g / cm ³ was passed twice through the pipe P to drain about 9370 kg of water (not shown).
About 50 kg of water remained in the pipe P. The pipe P is made of a soft urethane foam having a density of 0.03 g / cm ³ , and has a gas receiving surface 2 on one side which has the same elasticity, flexibility and non-permeability as the soft foam, and a diameter of 220 mm × 300 mm. , And dry air 5 having a dew point of −12 ° C. was blown from behind the gas receiving surface 2. As a result of performing this operation 10 times, about 39.9 kg of the remaining water of about 50 kg was absorbed and drained. The remaining 10.1 kg was dried due to the synergistic effect of vaporization. The results are shown in Table 1 below.

[0021]

[Table 1]

In the above embodiment, the amount of water absorption was measured for each pig speed of 1.5 m / sec, pressure of 0.1 kg / cm ² and the number of passes. Up to 1 to 3 times, the number of times used at a time was 2 or more. After passing 10 times, blowing was performed. The drying was confirmed by checking whether there was moisture in the pipe at the inlet, the outlet, the branch pipe opening in the middle of the pipe, and the like, and measuring the dew point at the outlet to compare the inlet dew point.

[0023]

COMPARATIVE EXAMPLE In the same manner as in the above example, a bullet-shaped pig made of a semi-rigid urethane foam having a density of about 0.12 g / cm ³ and having a diameter of 210 mm × 350 mm was passed through a pipe in which about 50 kg of water remained. Table 2 shows the results.

[0024]

[Table 2]

As is evident from the diagram in Table 2, the amount of water absorbed at one time is 40 to 10 g. As the amount of residual water in the pipe decreases, the amount of water absorbed further decreases. It was not completely dried even after passing 100 times.

[0026]

As described above, the present invention has a density of 0.0
One side end face of a soft foam of 2 to 0.06 g / cm ³
Non-permeable foam with the same shrinkage and flexibility as foam
Before the open-cell or closed-cell resin is polymerized
Break the foam into a paste, 0.05-0.8mm
A pig with a gas receiving surface, which is applied in a thickness, is placed in the pipe.
Insert and transfer pig with dry air with dew point 0 ° C or less
By drying the inner surface of the tube
Since those of the method for drying a tube inner surface, and a soft onset foam
Both the gas receiving surfaces are integrated and familiar, are able to absorb water while moving smoothly, and can sufficiently absorb moisture. In addition to having water retention, the dry air vaporization effect with a dew point of 0 ° C. or less can ensure drying, and can be performed 1/10 or more faster than the conventional method, greatly shortening the drying time, and improving work efficiency. . Further, since the water in the pipe is completely dried, a primer coating work applied to the base in the subsequent process can use the same type as the top coat paint, and a good lining with good adhesiveness can be obtained.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing a drying method of the present invention.

FIG. 2 is a side view of a pig used in the present invention.

FIG. 3 is a partially enlarged sectional view of a gas receiving surface.

FIG. 4 is an explanatory diagram of a conventional example.

FIG. 5 is a sectional view taken along line AA of FIG. 4;

[Explanation of symbols]

 1 Pig 2 Gas receiving surface 5 Dry air

Claims (1)

(57) [Claims] On one edge of the 1. A density of 0.02~0.06g / cm ³ flexible foam, consisting in a flexible and comparable contractile and flexible foam-impermeable foamed resin Open cell or
The foam before the closed cells are polymerized breaks into a paste.
Then, a pig having a gas receiving surface coated with a thickness of 0.05 to 0.8 mm is inserted into the tube, and the pig is moved by dry air having a dew point of 0 ° C. or less to dry the inner surface of the tube. A method for drying the inner surface of a pipe using a pig.