JP2000167929A - Manufacture of internally lined pipe - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of manufacturing an internally lined pipe wherein a lining can be easily formed on the internal surface thereof and moreover the permeability is low and an enhanced corrosion-resistance can be provided. SOLUTION: A tubular body 1 (billet) of thermoplastic resin is heated to a predetermined temperature in an oven 2. An end of the body 1 is clamped by a clamp 3 and the clamp 3 is pulled by a pulling means 5 such as a winch through a wire 4 so that the tubular body 1 is stretched to a length five times as large as its original length or more and drawn into a steel pipe 6, where it is heated to a predetermined temperature by a heater. After the stretched tubular body 1e is drawn fully into the pipe 6, the body 1e is not pulled any longer, and the pipe 6 and the body 1e are cooled through natural cooling. After being cooled to a predetermined temperature, the clamping by the clamp 3 is released and the body 1e is cut off from the body 1 to relieve the pulling force exerted on the body 1e, allowing the body 1e to come into close contact with the internal surface of the steel pipe 6.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing an inner surface coated tube whose inner surface is coated with a thermoplastic resin, and more particularly, to a process for solid-state drawing of a resin tubular body, drawing in the inner diameter of the tube, and coating the inner diameter. The present invention relates to a method for manufacturing an inner cladding tube having a step of performing the following.

[0002]

2. Description of the Related Art It is well known that the inner surface of a pipe such as a steel pipe is coated with a resin to suppress the corrosion of the pipe and extend the life. As a method of forming the resin coating on the inner surface of the steel pipe, in addition to a powder coating method (melt coating method) in which a resin powder is put into the steel pipe, and the steel pipe is rotated while the powder is heated and melted to coat the inner surface, A tension insertion method has been performed in which the resin tubular body is slightly stretched to reduce its diameter to be drawn into a steel pipe, the stretching force is released, and the resin tubular body is brought into close contact with the inner diameter of the steel pipe. In this tensile insertion method, the deformation ratio of the resin tubular body is very small, about 1.05 to 1.1 times.

[0003]

According to the former powder coating method, it takes a considerable amount of time and labor to form the coating, the cost is high, and the coating itself has a large permeability such as oxygen permeability, and the inner surface of the steel pipe has a large permeability. Insufficient corrosion inhibiting effect. In the latter conventional example of the tension insertion method, it is necessary to increase the thickness of the coating in order to reduce the oxygen permeation amount of the coating, and as a result, there is a disadvantage that the effective inner diameter of the steel pipe is reduced.

According to the present invention, an inner surface coating can be easily formed,
Moreover, it is an object of the present invention to provide a method for producing an inner cladding tube having a low permeability and an excellent corrosion inhibiting effect.

[0005]

According to a method of manufacturing an inner-coated tube according to the present invention, a tubular body of a thermoplastic resin is drawn into the inner diameter of the tube while being stretched and subjected to solid-phase deformation, and the inner peripheral surface of the tube is formed of the resin. In the method for producing an inner cladding tube covered with a stretched product of a tubular body, the tubular body is subjected to solid phase stretching at a deformation ratio of 5 or more so that the thickness of the tubular body of the thermoplastic resin is 20% or less. It is characterized by being drawn into the inner diameter of a tube.

[0006] According to the method for manufacturing an inner cladding tube, a coating can be easily formed on the inner surface of a pipe such as a steel pipe by a tensile insertion method. Further, by setting the deformation ratio at the time of the solid phase stretching to 5 times or more, the permeability of oxygen and the like becomes extremely small, and the corrosion inhibiting effect becomes extremely excellent.

[0007]

FIG. 1 is a schematic sectional view showing a method for manufacturing an inner cladding tube according to an embodiment, in which a tubular body (billet) 1 of a thermoplastic resin is heated to a predetermined temperature in an oven 2. Have been. The end of the tubular body 1 is chucked by a clamp 3 and the clamp 3 is pulled by a pulling means 5 such as a winch via a wire 4 so that the tubular body 1
It is stretched at a deformation ratio of twice or more and drawn into a pipe (steel pipe in this embodiment) 6. The steel pipe 6 is heated to a predetermined temperature by a heater (not shown).

After the drawn tubular body 1e is drawn into the entire inside of the steel pipe 6, further drawing is stopped and the steel pipe 6
Then, the stretched tubular body 1e is cooled by standing to cool. After the temperature is lowered to a predetermined temperature, the chuck by the clamp 3 is released, and the billet portion and the elongated tubular body 1e are cut.
The stretched tubular body 1e is brought into close contact with the inner surface of the steel pipe 2 by releasing the tensile force applied to the stretched tubular body 1e.

According to such a manufacturing method, a steel pipe whose inner surface is coated with a resin can be manufactured very easily. Further, by setting the deformation ratio to 5 times or more as described above, the transmittance of the coating, such as oxygen, is significantly reduced as will be apparent from the examples described later.

The resin of the tubular body used in the present invention includes:
A crystalline thermoplastic synthetic resin is used.

Preferred examples of such resins include unsubstituted or halogen-substituted vinyl polymers, unsubstituted or hydroxy-substituted polyesters, polyamides, polyetherketones, aliphatic polyketones, polyoxymethylenes and the like.

More preferably, a linear polymer of ethylene or propylene or a linear copolymer of ethylene or propylene with at least one other comonomer, polyvinylidene fluoride, polyoxymethylene and at least one other of these. And a copolymer with a comonomer.

Particularly preferred is a linear polymer of ethylene or propylene or a linear copolymer of these with at least one comonomer.

The thermoplastic resin may contain a fibrous filler such as glass and carbon, a plate-like filler such as talc and mica, or a granular filler such as calcium carbonate, barium sulfate and carbon.

The synthetic resin tubular body serving as a billet can be formed by extrusion molding or injection molding of a thermoplastic resin. Further, a block-shaped object may be formed into a pipe shape through a cutting process.

The thickness and diameter of the billet (tubular body 1) may be determined based on the hole diameter of the steel pipe 6, the final coating thickness, and a predetermined deformation ratio.

The deformation ratio is as large as 5 times or more (magnification at which the thickness of the tubular body 1 becomes 20% or less of the original thickness), and is particularly preferably 7 to 20 times. By increasing the deformation ratio in this way, the permeability of oxygen and the like is significantly reduced.

When the end of the tubular body 1 is chucked by the clamp 3, the clamp 3 has a smaller diameter than the inner diameter of the steel pipe 6 so that the clamp 3 can freely pass through the steel pipe 6.
It is preferable to reduce the diameter of the end of the tubular body 1 by cutting the outer peripheral side of the end, or the like, and chuck the end with the clamp 3.

In order to smoothly introduce the tubular body 1 into the steel pipe 6 while being stretched into the steel pipe 6, a tapered guide member may be arranged on the inlet side of the steel pipe 6, and the inlet side of the steel pipe 6 may be tapered. The guide surface may have a shape. Reference numeral 6a denotes a flange provided on the steel pipe 6.

As the clamp 3, various types such as a mechanical type, a hydraulic chamber, and a pneumatic type can be used. As the pulling means 5, various pulling devices such as a cylinder mechanism can be used in addition to a winch. It is to be noted that, as a matter of course, the tension means 5 is capable of applying a force exceeding the yield stress of the tubular body 1 to the tubular body 1. When stretching the tubular body 1 by stretching, a former may be used. The heating temperature of the tubular body 1 is determined by the melting point m _{p of the} thermoplastic resin constituting the tubular body 1.
Lower than Preferably, the heating temperature (m _p -
Preferably in the range from 15 ° C.) of (m _p -90 ℃). Cooling is usually performed by air cooling or water cooling.

For the purpose of increasing the adhesion between the resin coating layer and the inner surface of the steel pipe, the following formulation may be used.

The resin is modified by adding an adhesive substance in advance. Apply adhesive to outer surface of billet before insertion. Treat the outer surface of the billet before insertion. Treat the inner surface of the steel pipe before insertion. In the case of the method of maleic anhydride, vinyl acrylate,
A polyolefin-based material modified with vinyl acetate or the like is preferably used.

In the case of the above method, a reactive adhesive such as an epoxy adhesive or an isocyanate adhesive, or a hot melt adhesive such as a vinyl acetate-ethylene copolymer is preferably used.

In the case of the method (1), discharge ozone treatment, plasma treatment, flame treatment and the like are preferably used, and it is more effective to carry out the method in combination with the method (2).

In the case of the above method, a cleaning treatment such as high-pressure steam cleaning, a surface oxidation treatment such as a plasma treatment and the like are preferably used.

[0026]

EXAMPLE 1 A stainless steel pipe 6 was formed according to the method shown in FIG.
Was formed with a resin coating on the inner hole.

The outer diameter of the steel pipe was 60.5 mm, the inner diameter was 52.7 mm, the wall thickness was 3.9 mm, and the length was 500 mm. Tubular body (billet) made of polyvinyl fluoride difluoride (KF1200 glass transition temperature -35 ° C manufactured by Kureha Chemical Co., Ltd.) Oxygen permeability 2.2 (cc · mm / m ² · 24 hrs · atm) Outer diameter 60 mm Inner diameter 50mm Thickness 5mm Cut the outer periphery of the end of this billet and chuck with a clamp. Temperature in oven 90 ° C (room temperature 27 ° C) Tensile means Motor winch Tensile force 3.8 ton f The procedure is as follows.

A tubular body (a billet) equipped with a clamp 3
After keeping 1 at 90 ° C. for 1 hour in the oven 2, the tubular body 1 was stretched by a motor winch using a former at a deformation ratio of 10 times. Outer diameter 52.6mm by stretching
(Wall thickness: 0.5 mm) and was drawn into the steel pipe. When the clamp 3 passes through the steel pipe 6, the tension is stopped, and
It was left to cool to ° C. Next, the stretched tubular body 1 e was cut along both ends of the steel pipe 6. As a result, the tensile force applied to the tubular body 1e was released, and the tubular body 1e expanded in diameter and came into close contact with the inner peripheral surface of the steel pipe 6.

The oxygen permeability of the coating thus formed was 0.7 cc · mm / m ² · 24 hrs · atm.

Examples 2 to 5, Comparative Examples 1 and 2 Resin-coated steel pipes were produced in the same manner as in Example 1 except that the deformation ratio was as follows.

Example 2 7 Example 3 12 Example 4 16 Example 5 18 Comparative Example 11 Comparative Example 24 The measurement results of the oxygen permeability of these coatings are shown in FIG.

As is apparent from FIG. 2, it is clear that the oxygen permeability is significantly reduced by setting the deformation ratio to 5 times or more. The deformation ratio is 15 times or more, especially 20 times.
When the ratio is twice or more, the decrease in oxygen permeability is almost saturated, so it is clear that the deformation ratio is preferably 5 to 20 times, particularly 7 to 15 times.

Example 6 A tubular body (a billet) was formed from a material obtained by kneading 80% by weight of polyvinyl difluoride, 10% by weight of methyl methacrylate, and 10% by weight of glycidyl methacrylate with a twin-screw extruder, and formed a steel pipe. A resin-coated tube was manufactured in the same manner as in Example 1, except that a maleic anhydride-modified polyolefin-based hot melt adhesive was applied to the billet surface before the insertion.

The adhesion between the coating layer of the obtained cladding tube and the steel pipe was extremely good.

[0035]

As described above, according to the present invention, there is provided a tube having an inner surface coating having extremely low permeability to oxygen and the like.
And, since the coating has a small transmittance, a thin coating gives sufficient corrosion resistance to the inner surface of the tube, and the effective sectional area of the inner surface of the tube can be increased. According to the present invention, the formation of the coating is very simple because the coating is formed by one step of stretching and cutting the tubular body.

[Brief description of the drawings]

FIG. 1 is a schematic diagram illustrating a method for manufacturing an inner cladding tube according to an embodiment.

FIG. 2 is a graph showing data of Examples and Comparative Examples.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Tubular body (billet) 2 Oven 3 Clamp 4 Wire 5 Tension means 6 Steel pipe

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Urash Ibrahim 1542-5 Koshigoe, Kamakura-shi, Kanagawa F-term (reference) 4F210 AA04 AA11 AA15 AA16 AA24 AA29 AD03 AD05 AD12 AD16 AD19 AD29 AG03 AG08 AH43 QA09 QC01 QD14 QG04 QG17 QT07 4F211 AA04 AA11 AA15 AA16 AA24 AA29 AD03 AD05 AD12 AD16 AD19 AD29 AG03 AG08 AH43 SA13 SC03 SD04 SH06 SH10 SH18 SJ01 SJ06 SJ13 SJ15 SJ22 SP21 SP22 SP43

Claims (2)

[Claims] 1. A method for producing an inner coating tube in which a thermoplastic resin tubular body is drawn into the inner diameter of a tube while being stretched and subjected to solid phase deformation, and the inner peripheral surface of the tube is covered with a stretched product of the resin tubular body. (C) producing a tubular body having a tubular body made of a thermoplastic resin, wherein the tubular body is subjected to solid-phase stretching at a deformation ratio of 5 times or more so that the wall thickness of the tubular body becomes 20% or less and drawn into the inner diameter of the tube; Method. 2. The method according to claim 1, wherein the deformation ratio is 7 to 2.
A method for producing an inner cladding tube, characterized in that it is 0 times.