JPH03277529A - F r p tube with screw coupler and manufacture thereof - Google Patents

Abstract

PURPOSE:To obtain an F R P tube having a male screw part with an axially excellent strength by raising and flocking staple fibers by an electrostatic flocking method on the male screw forming end outer peripheral surface of the tube in which fibers are wound round a mandrel, in the manufacture of an F R P tube by an FW method in which fibers impregnated with resin are wound round the mandrel, and thereafter, impregnating and curing resin into the flocked part thereof and then forming a male screw by machining. CONSTITUTION:In an F R P tube, the male screw formed end part A consists of thin wall FW parts 10 formed into a tube by an FW(filament winding method) method and a resin impregnation-raised and flocked part 20 provided on the entire outer peripheral surface thereof, and a male screw part B is formed by machining the outer peripheral surface of the resin impregnation-raise and flocked part 20. The parts except the male screw formed end part A is made into a single layered structure of the FW parts 10. The male screw formed end part A is a three layered structure in which the resin impregnation raised and flocked part 20 is held between the FW parts 10, 10. And, the male screw B is formed such that it reaches the resin impregnation raised and flocked part 20.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an FRP pipe with a screw joint member in which a male thread is formed on the outer peripheral surface of at least one end of the FRP pipe, and a method for manufacturing the same.

[Conventional technology]

Taking advantage of the characteristics of lightweight, high strength, and high corrosion resistance, FRP pipes have been used in a wide range of applications, from chemical plant piping, hot spring piping, and seawater piping to line vibes for crude oil and natural gas transportation, and oil country tubular goods for crude oil drilling. There is.

The most important and technically difficult aspect of piping is the coupling system, and the same is true for FRP pipes.

Currently, plug-in adhesive joints, flange joints, threaded joints, and various mechanical joints are used as joints for FRP pipes, but screw joints, especially API joints, are used for high-pressure piping such as crude oil transportation line pipes and oil country tubular goods. (American Petroleum Institute) standard screw joints are often used.

FRP pipes used for high-pressure piping such as line pipes for crude oil transportation and oil country tubular goods are usually manufactured by the filament winding method (FW method). The FW method is a method in which continuous long fibers (rovings) impregnated with resin are wrapped around a mandrel mold under tension and formed into a tubular shape.A screw joint is applied to an FRP pipe formed by the FW method. Regarding the female threaded part, a method is used in which a mandrel mold with a left-handed thread shape is used and the winding is performed in the same way as the noise body part.This method is based on machining. Because there is no fiber, there is no risk of tearing the fibers.
High strength can be expected.

On the other hand, with regard to the tapered portion, it is common practice to form a thread by machining the circumferential surface of the tube end after tube forming. In this case, since the fibers are cut, it is difficult to obtain a male threaded portion with high strength. A method to increase the strength of the male threaded portion is disclosed in Jikai W60-11345, but this is intended for FRP round bars made by pultrusion, and cannot be applied to FRP pipes made by the FW method. It is.

By the way, the forces that act on a neck joint of a pipe include internal pressure and axial tensile force. Of these, failure due to axial tensile force occurs in the form of shear failure of the screw bottom surface. Therefore,
In order to obtain a male thread with high breaking strength, it is necessary to strengthen the threaded part against shearing force, and in FRP pipes made using the FW method, fibers are oriented in the direction of the inner thickness of the threaded part to improve glabellar shearing force. It is considered effective to do so. In line with this idea,
The present inventors proposed in Japanese Patent Laid-Open No. 63242523 that a fiber-reinforced fabric in which fibers are oriented in three-dimensional directions is used to form a male thread.

[Problems to be Solved by the Invention] A three-dimensional fabric is a cross laminate made of a plurality of woven fabrics with two-dimensional orientation of fibers composed of warp yarns and weft yarns, which are oriented vertically in the thickness direction. If this is used, a vertical system will remain even after machining, and this will exist in the height direction of each thread, creating a male thread with extremely high glabella shear strength (axial force). It will become.

However, since three-dimensional fibers are expensive, FRP pipes using them for the male thread forming part have the problem of high manufacturing costs and difficulty in popularizing them for boat fishing.

The present invention has been made in view of the above circumstances, and its purpose is to provide an FRP pipe with a screw joint member that has high strength in the male thread portion and is inexpensive to manufacture, and a method for manufacturing the same.

[Means for Solving the Problems] The FRP pipe with a screw joint member of the present invention is characterized in that the male thread forming portion of the outer layer at the end of the pipe is made of resin-impregnated short fibers with raised flocks.

As a method for planting short fibers upright on the outer peripheral surface of the end portion of the FRP pipe, for example, an electrostatic flocking method can be applied.

In the manufacturing method of the present invention, in manufacturing an FRP pipe by the FW method in which resin-impregnated fibers are wound around a mandrel, an electrostatic flocking method is applied to the outer circumferential surface of the male thread-forming end of the pipe obtained by winding the fibers around the mandrel. After the short fibers are erected and flocked, the flocked portion is impregnated with resin and hardened, and a male thread is formed by machining.

[For production]

FIG. 1 is a sectional view of an end portion of an FRP pipe showing one embodiment of the present invention.

In this FRP pipe, the male thread forming end A is composed of a thin-walled FW section 10 formed into a tubular shape by the FW method, and a resin-impregnated upright flocked section 20 provided around the entire outer circumference of the FW section. A male threaded portion B is formed by machining the outer peripheral surface of the portion 2o. The portion other than the male thread forming end A has a single layer structure of the FW section 10.

FIG. 2 shows another embodiment of the present invention, in which the male threaded end A has a three-layer structure in which a resin-impregnated raised flocked part 20 is sandwiched between FW parts 10 and 10. The male threaded portion B is formed to reach the resin-impregnated raised flocked portion 20.

In this way, by making the male thread forming part located on the outer layer of the pipe end of the FRP pipe the resin-impregnated raised flocked part 2o, the male thread forming part is reinforced by the FWIIO of the inner layer, and moreover, the male thread forming part is The fibers are oriented in
By ensuring excellent glabellar shearing force even after male thread processing, high strength against axial tensile force is exhibited.

The resin-impregnated raised flocked portion 20 is easily formed, for example, by using an electrostatic flocking method. The electrostatic flocking method is a method in which short fibers are negatively charged with a high voltage and are caused to stand up and adhere to a grounded substrate by electrostatic force. After flocking, this is impregnated with resin and hardened to form a resin-impregnated raised flocked part 20.

The short fibers used in the resin-impregnated raised flocked portion 20 include:
Preferably, the length is about 1 to 3 so.

If the length of the short fibers is short, orientation in the thickness direction is difficult, and the axial tensile strength of the male thread forming portion decreases. However, even if the fiber length increases, the axial tensile strength of the male thread forming portion does not change.

As the type of short fibers, glass fibers, carbon fibers, or fibers such as polyamide, polypropylene, and polyester can be used.

The resin to be impregnated into the short fibers is preferably a thermosetting resin such as epoxy, polyester, vinyl ester, or phenol, and preferably a fast-curing resin.

If the resin curing time is long, the work will take a long time, leading to an increase in manufacturing costs.

Particularly preferred fast curing is photocuring using unsaturated polyester resin, vinyl ester resin, or the like. According to photocuring, curing can be completed in 2 to 7 minutes using, for example, visible light (400 to 500 m) and a light intensity of 20 to 30 mW/d. Further, in addition to photocuring, if short-time curing can be performed by thermal curing or blending of a curing agent, such methods can also be applied.

The resin-impregnated raised flocked part 20 needs to have a thickness that can include the male screw part B, but if it is too thick, the FW part IO of the inner layer becomes thin, making it difficult to ensure the strength as an FRP pipe. Therefore, it is desirable that the thickness not exceed 50% of the tube wall thickness.

The resin-impregnated raised flocked portion 20 before forming the male threaded portion B is as follows:
As shown in FIG. 2, it can be thinly covered with the FW section 10 from above. By doing this, the resin-impregnated raised flocked part 2
After forming the male thread part B on the threaded part B, the occurrence of a disconnection between the FW part 10 and the resin-impregnated raised flocked part 20 on the surface of the male threaded end part A is prevented, and the strength of the male threaded end part A is improved. do.

When covering the resin-impregnated raised flocked part 20 with FW6610, the raised flocked part is cured with resin and then the FW part 1 is covered with FW6610.
form 0. If the FW method is performed on the raised fibers, the flocked fibers will be compressed and will no longer be in an erect state, so that the fibers will no longer be oriented in the thickness direction.

〔Example] Examples of the present invention will be explained below in comparison with comparative examples.

The FRP shown in Fig. 3 has a male screw part at the end consisting of a round thread of 8 threads/inch as specified in the API standard (5B).
The following manufacturing experiment was conducted on the tube.

For tube forming using the FW method, glass roving is used as the fiber for wrapping (product name Glassron: manufactured by Asahi Fiberglass).
The impregnating resin used was a bisphenol type epoxy resin (trade name: Epicoat 828: manufactured by Yuka Shell Epoxy ■) and an acid anhydride curing agent (trade name: HN-2200: manufactured by Hitachi Chemical ■) at 100/80 (wt). A mixture of these was used.

First, an FRP tube having a thickness of 511I11 was formed by the FW method using a straight tube forming mandrel having an outer diameter of 2°992 inches.

Next, glass fibers with a diameter of 13 μm and a length of 2 m were placed on the outer peripheral surface of the male thread forming end (80 g length) using an electrostatic flocking machine (E
IINST ROEDER5TEIN ERO-FL
(OCK-BG1978-7001 type) is used with a voltage of 80
Hair was transplanted using kV. Next, vinyl ester resin (
Lipoxy R802: manufactured by Showa Kobunshi ■) and light curing agent (■L
C-1. By impregnating flocked fibers with VLC-2 (manufactured by Nippon Oil & Fats Ltd.) and curing it by irradiating it with a tungsten lamp at a light intensity of 30 mW/cd for 2 minutes, a 4-thick resin-impregnated raised flock was created. The division was formed.

Thereafter, FRP pipes were laminated to a thickness of 4.6 mm over the entire length of the outer peripheral surface by the FW method. Finally, a male threaded portion was formed on the outer peripheral surface of the male threaded end portion by machining. Due to the formation of the male threaded portion, most of the resin-impregnated raised and raised hair portions were exposed on the outer circumferential surface of the male threaded portion (see Fig. 2).

Experiment 1 was carried out in the same manner as in Experiment 1, except that the fibers used for the resin-impregnated raised flocked portions were polyamide fibers with a diameter of 20 μm and a length of 2 mm.

As a resin used for the resin-impregnated raised flocking part, 100 parts by weight of vinyl ester PJ resin and 0.5 p of cobalt naphthenate are added.
hr, methyl ethyl ketone peroxide 1. Q p
hr added, and blow it with hot air (90°C x 2
The procedure was the same as in Experiment 1, except that it was cured for 0 minutes).

The procedure was the same as in Experiment 1 except that the resin-impregnated raised flocked part (thickness: 4.6 m) was arranged as the outermost layer of the male thread forming end (1st experiment).
(see figure).

Comparison 1: The entire male threaded end was molded using the same FW method as the other parts. The conditions for the FW method were the same as in Experiment 1.

Comparison 1 The FW method was carried out without impregnating and curing the upright flocked area with resin. The rest was the same as in Experiment 1.

An axial tensile test was conducted on the male threaded portions of the FRP pipes manufactured in Experiments 1 to 6. The Neshi compound is made by LOR, an American OCR company.
-105 was used, and the tightening torque was 25 kg-m.

The results are shown in Table 1. The average shear strength is the value obtained by dividing the breaking load by the area of the male thread. As is clear from Table 1,
In the example of the present invention, the axial strength of the recessed portion is significantly improved.

Table 1 Note that in the FRP pipe of the present invention, the male threaded portion may be provided at one end of the pipe, or may be provided at both ends of the pipe.

〔Effect of the invention〕

As is clear from the above description, the FRP pipe with a threaded joint of the present invention has a male threaded portion with significantly improved axial strength, and furthermore, the male threaded end portion is easy to form, and the manufacturing cost is low. is cheap. Furthermore, the manufacturing method of the present invention provides the male threaded portion with extremely excellent axial strength, and moreover, allows the male threaded end portion to be formed economically.

[Brief explanation of the drawing]

1 and 2 are cross-sectional views showing a camphor according to the present invention;
FIG. 3 is a sectional view showing the shape of an FRP pipe manufactured in an example of the present invention. lQ: FW part, 20: resin-impregnated raised flocked part, A: male thread forming end, B: male thread part. Phase diagram diagram

Claims (2)

[Claims] (1) F with a threaded joint member characterized in that the male thread forming portion of the outer layer of the pipe end is made of resin-impregnated short fibers with raised flocks.
RP tube. (2) In manufacturing FRP pipes using the filament winding method in which resin-impregnated fibers are wound around a mandrel, short fibers are applied to the outer circumferential surface of the end where the external thread is to be formed by electrostatic flocking. 1. A method for manufacturing an FRP pipe with a threaded joint member, characterized in that after the raised flocking is carried out, the flocked part is impregnated with resin and hardened, and a male thread is formed by machining.