JPH08155413A - Pig - Google Patents

Abstract

PURPOSE: To keep good water retaining capacity even at the time of compression or deformation generated at the time of the passage through the joint part or bent part of piping, in a pig composed of sponge like porous foam subjected to the extrusion of the residue in the piping, by wholly compounding a water retaining agent with the pig in a dispersed state. CONSTITUTION: A pig 1 is produced by forming sponge like soft porous foam such as polyurethane foam and wholly compounding a water retaining agent with the compsn. of the foam or the contour part thereof in a dispersed state. That is, in the case of polyurethane foam, the water retaining agent 2 is premixed with polyol being a raw material and isocyanate is mixed with the resulting premix under stirring to form water retaining agent dispersed foam. Or, a conventional pig is used as a core material and the same material is arranged to the periphery of the core material to form the pig 1 having the water retaining agent 2 dispersed in the contour part thereof.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sponge-like soft porous foam pig used for extruding a residue in a pipe.

In cleaning the inside of a pig, water pressure is often used as a pig pressure source. After the cleaning work, it is often practiced to pump the pig a number of times through the pipe with compressed gas in order to remove water in the pipe.

[0003]

2. Description of the Related Art Non-hydrophilic elastic bodies are typical of conventional pigs used for this type of application. In such a pig, water is forced to remain in a film form on the inner peripheral surface of the pipe, and when this pipe is used for transferring oil, paint, solvent, etc., water is mixed into them, which is not preferable. Further, when the inner wall of the pipe is lined with a resin or the like after cleaning the inside of the pipe, the lining film is deteriorated, which is not preferable.

[0004] Conventionally, a pig made of a soft foam is also known, which absorbs water in the void of the pig due to a capillary phenomenon, but has a low water absorption capacity and a poor ability to retain the absorbed water, and therefore a pipe joint. When passing through a narrow portion such as a portion or a welded portion or a bend portion, the absorbed water is discharged due to contraction or deformation. Also, the absorbed water is released by being pressed by the compressed air, that is, compressed by pumping.

[0005]

SUMMARY OF THE INVENTION An object of the present invention, in a sponge-like soft porous foam pig, is to compress, deform or use compressed air when passing through a joint, weld, bend or the like of a pipe. It is intended to maintain a good water retention capacity even when compressed by pushing, and to effectively adsorb a small amount of water in the pipe.

[0006]

A pig according to the present invention is a sponge-like soft porous foam in which a water retention agent is dispersed and mixed as a whole, or a sponge-like soft foam in which a water retention agent is dispersed and mixed in an outer shell portion. Characterized by a soft porous foam.

In the present invention, the water retention agent includes starch-acrylic acid graft polymer, carboxymethyl cellulose crosslinked product, polyvinyl alcohol crosslinked polymer, vinyl acetate-acrylic acid ester copolymer saponified product, sodium polyacrylate crosslinked product and the like. Can be filled with the super absorbent polymer.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to the drawings showing an embodiment of the present invention,
The present invention will be described.

The pig 1 is formed from a sponge-like soft porous foam such as sponge rubber or polyurethane foam into a block shape or a spherical shape, and a water retention agent 2 is dispersed and mixed in the composition of the foam, Alternatively, the form (form) in which the water retention agent 2 is dispersed and mixed in the outer part is shown in FIG. 1, and the form (form) in which the water retention agent 2 is dispersed and mixed in the outer part is shown. It is shown in FIG.

In the case of the polyurethane foam, for example, a polyurethane foam is prepared by mixing a water retention agent in the starting material polyol and then mixing and stirring the isocyanate to obtain a water retention agent dispersed foam. Conventionally, a pig is used as a core material, the materials described in the form are arranged around the core material, and the pig is molded by a method known per se to obtain a pig having a water retention agent dispersed in the outer shell.

The amount of the water retention agent added is 0.1 to 0.1 depending on the type.
It may be 20% by weight / pig volume% (% by weight with respect to the pig volume), and 0.1-20% by weight in the case of the above type / volume% of the outer shell portion (weight% with respect to the outer shell volume).

When the pig according to the present invention is passed through a pipe, if there is bottom accumulated water in the pipe or film-like adhered water remains on the inner peripheral surface of the pipe, the water or water is removed from the pig. The water-retaining agent blended in (1) absorbs and expands, and the particles become larger, blocking some of the voids in the pig.

This type of sealing is effective for the whole pig in the type, and is effective for the outer portion of the pig in the type.

In this manner, the moisture absorbed in the voids of the pig is compressed or deformed when the pig passes through the joints, welds and bends of the pipe, or compressed by compressed air. Less likely to be released.

Incidentally, in the sample of the pig of the present invention of the type containing 2% by weight / pig volume% of the water retention agent, the water absorption by the soft foam having the same porosity and the same volume as that of the pig of the present invention is obtained except that the retention agent is not contained. From the experimental results, it was confirmed that the water retention rate of the conventional pig was about 5 times that of the comparative example. 2 water retention agents
It was confirmed from the experimental result that the sample according to the present invention of the type containing the weight / volume of the outer shell (porosity, volume is the same as the former sample) has about 3 times the water retention rate of the comparative example.

Further, since the pig according to the present invention has the excellent holding ability as shown above, it brings about an effective adsorption of a trace amount of water in the tube.

[0017]

As described above, according to the present invention, a sponge-like soft porous foam pig is compressed, deformed, or compressed with compressed air when passing through joints, welds, bends, etc. of pipes. A good water retention capacity can be maintained even when compressed by pushing, and adsorption of a small amount of water in the tube can be made effective.

[Brief description of drawings]

FIG. 1 is a sectional view showing an example of a pig according to the present invention.

FIG. 2 shows a sectional view of another example of a pig according to the present invention.

[Explanation of symbols]

 1 pig 2 water retention agent

Claims (2)

[Claims] 1. A pig made of a sponge-like soft porous foam in which a water retention agent is dispersed and compounded as a whole. 2. A pig made of a sponge-like soft porous foam in which a water retention agent is dispersed and mixed in the outer shell.