JPH0583592B2 - - Google Patents

Description

Detailed Description of the Invention <Field of Industrial Application> The present invention provides a sealing material for corrosion-resistant steel pipes that is useful for filling and sealing a relatively large gap formed between a joint body and a transport pipe body, and the seal. The present invention relates to a sealing method using a material.

<Prior art and its problems> Conventionally, corrosion protection for joints consisting of pipe bodies for transporting gas, water, etc. and joint bodies has been achieved by spirally applying anti-corrosion tape made of plastic film or seals with an unvulcanized rubber layer. This is done by wrapping a non-woven fabric in a shape or by wrapping an anti-corrosion tape made by impregnating a non-woven fabric with an anti-corrosive substance such as petrolatum.

In recent years, corrosion-resistant steel pipes with plastic lining on the surface of large-diameter steel pipes have been used as transport pipes, and heat-shrinkable tubes are increasingly being used to prevent corrosion at joints.

On the other hand, small or medium diameter steel pipes are also generally lined with plastic, and the joints in this case are mostly threaded.

Therefore, the joint body is referred to as a transportation pipe body, and as shown in FIG. A lining layer 22 having a tip portion having a threaded portion 21 screwed onto the inner surface of the joint pipe.
Since it is composed of steel pipes 23 with a
There is a problem that water enters this area and corrodes the steel pipe, and attempts have been made to fill it with base-type sealing materials or solvent-based adhesives, but air bubbles are formed during filling. However, due to problems such as fading due to evaporation of the contained solvent, a sufficient anticorrosion effect cannot be obtained over a long period of time.

In addition, as a sealing material to solve this drawback, a tape-shaped sealing material having specific ingredients and physical properties has been proposed, as described in Japanese Patent Application Laid-Open No. 149495/1983. This sealing material solves many of the drawbacks of the conventional sealing material, but the thickness becomes uniform due to uneven tension when the tube body 2 is wrapped around the threaded portion 21, resulting in uneven filling. This has the disadvantage that the winding operation is complicated.

<Means for Solving the Problems> In view of the state of the prior art, the present inventors have developed a device that is essentially a donut, which can provide a good anti-corrosion effect simply by attaching it to a transportation pipe body and screwing it onto a joint body. As a result of intensive research on sealing materials of the shape of the shape, it was found that the thin film contains a roughly doughnut-shaped thin film having a hollow part and a fluid sealant component as essential components, and the thin film has easy breakability and good dispersibility. The inventors have discovered that the above object can be satisfied, and have arrived at the present invention.

That is, the present invention comprises a joint body provided with a lining layer protruding from the end of the pipe on the surface of the joint pipe, and a transport pipe body with a lining layer having a threaded portion at its tip portion to be screwed onto the pipe. A substantially donut-shaped sealing material that fills a gap between the protruding lining layer of the joint body and the pipe body at the joint portion,
The material is composed of a roughly donut-shaped thin film having a hollow part inside and a fluid sealant filling the hollow part, and the thin film has easy breakability and good dispersibility. be.

In the sealing material of the present invention, the thin film is easily destroyed (or ruptured) under a low load, and the broken thin film pieces are dispersed in the sealing material having appropriate softness and elasticity to reliably fill the gap. Therefore, it exhibits a good anticorrosion effect.

<Configuration> The present invention will be specifically described below with reference to the drawings. In FIG. 2, 3 is the sealing material of the present invention,
The sealing material 1 is approximately donut-shaped (it may be ring-shaped, disk-shaped, etc.), and the inner diameter and outer diameter are determined by the size of the transport pipe (or joint pipe). Usually the inner diameter is about 10-100mm, the outer diameter is about 12mm
~120mm, and the thickness ranges from 1 to 10mm.
Moreover, the width is usually in the range of 3 to 50 mm. The thin film constituting the sealing material 3 has a thickness of 0.5 to 300 μm,
When the pipe body and the joint pipe are screwed together, it is destroyed (or broken) under a low load, and is almost uniformly mixed with the sealant 32 that has been broken into pieces and pushed out due to the destruction (or breakage). It has dispersibility.
If it lacks easy breakability and good dispersibility, the broken thin film pieces will act as a water bypass between the outside and the threaded part, causing water to enter the threaded part and corrode the threaded part, which is undesirable. From this point of view, it is preferable that the material of the thin film has excellent affinity with the sealant.

Such a thin film is selected from a film made of an aqueous dispersion of natural rubber or synthetic rubber latex, synthetic resin emulsion, etc., and has an elongation of 300% or less and a breaking strength of 200 kg/cm ² or less. The growth
If it exceeds 300%, it will take a high load to break the thin film, and it will be difficult to break at the desired location, resulting in a decrease in breaking strength.
If it exceeds 200 Kg/cm ² , the filling operation is completed without the thin film breaking into pieces, and large pieces of the thin film remain, which may form a bypass for the above-mentioned water, which is not preferable.

In addition to the above-mentioned aqueous dispersion, the thin film may also be a wax or the like having a melting point of 50° C. or higher.

The fluid sealant mainly contains a rubber component, a filler component, and a softener component, and also contains adhesion-imparting resins such as rosin, rosin derivatives, terpene resins, petroleum resins, and phenol resins, pigments, Compounding agents such as anti-aging agents, stabilizers and ultraviolet absorbers are added, preferably 10 ² to ^{10 6} poise, practically
The viscosity is adjusted to 10 ³ to 10 ⁵ poise (each at 25°C).

Rubber components used in the present invention include rubbers such as polyisobutylene, butyl rubber, recycled butyl rubber, modified butyl rubber, ethylene-propylene rubber, and ethylene-propylene terpolymer rubber, and one or more of these may be used.

Mineral materials such as calcium carbonate, talc, clay, and titanium oxide are often used as filler components, but asbestos, glass fiber, and cork powder can also be used. Paraffin, lubricating oil, coal tar, aliphatic oil, wax, low molecular weight plasticizer, DOP, DBP, etc. are used.

The sealing material of the present invention is produced by providing a fluid sealing agent injection port in advance in a thin film formed in a roughly donut shape having a hollow portion inside, and filling the sealant through the injection port and then closing the film. For example, by filling a hopper with a predetermined sealant formulation and extruding it in a cylindrical shape from an extrusion port,
It can also be produced by cutting it into a roughly donut shape by cutting it to a predetermined width, immersing it in a bath of the aqueous dispersion or a bath of molten wax, taking it out, and sending it to a thin film forming process such as air drying, heating drying, or cooling. .

The latter manufacturing method has the advantage that shape-retaining means such as cooling can also be used immediately after extrusion, and that production is simple and a uniform sealing material can be produced at low cost.

<Examples> Examples of the present invention will be shown below. The text middle part means the weight part.

Example: Into the hopper of an extruder, 25 parts of butyl rubber, 50 parts of polyisobutylene, and 20 parts of dibutyl octyl phthalate were added.
20 parts of petroleum resin (softening point 100℃), 20 parts of process oil, 175 parts of talc, and 10 parts of titanium oxide were added and mixed.
It was extruded into a cylindrical shape with an outer diameter of 38 mm and cut into a width of 20 mm. The viscosity of this sealant is approximately 10 ⁴ poise (at25
℃).

Next, this was immersed in SBR latex having a solid content of about 50% by weight for about 30 seconds, taken out and air-dried to obtain a sealing material of the present invention. The SBR thin film had a thickness of about 20 μm, an elongation of about 220%, and a breaking strength of 100 Kg/cm ² .

This sealing material was attached to the threaded part of the pipe body shown in Figure 1, and a joint pipe was screwed onto it to connect it.
The gaps were completely filled, and the SBR thin film was properly dispersed, demonstrating good corrosion protection.

<Effects> Since the sealing material of the present invention is configured as described above,
In addition to being easy to attach to the pipe body, since it is a molded product, it is possible to form a sealant with a uniform thickness on the threaded part of the pipe body, so even if it is filled into the gap by screwing, there will be no unevenness in the gap. It has the characteristic that it does not occur.

Moreover, since the thin film is easily breakable and has good dispersibility, it can be filled with a low screwing pressure (torque pressure), and good anti-corrosion properties can be obtained after filling.

[Brief explanation of the drawing]

FIG. 1 is a partial sectional view of a connecting portion between a transport tube and a joint pipe using the sealing material of the present invention, and FIG. 2 is a perspective view of the sealing material of the present invention. 31... substantially donut-shaped thin film, 32... fluid sealant.

Claims (1)

[Scope of Claims] 1. Consists of a roughly donut-shaped thin film with a hollow part inside and a fluid sealant filling the hollow part, and the thin film has an elongation of 300% or less and 200 Kg/cm ² A sealing material having the following breaking strength: 2. The sealing material according to claim 1, wherein the fluid sealant has a viscosity of 10 ² to 10 ⁶ poise (at 25°C).