JPH09303672A - Steel pipe pipe end screw protector - Google Patents

Abstract

(57) 【Abstract】 PROBLEM TO BE SOLVED: To prevent rust generated in a seal portion of a male screw provided at a steel pipe end. SOLUTION: A taper cylindrical body 2 having an internal thread provided on the inner peripheral surface thereof with a female thread 2a to be engaged with a male thread of a steel tube 21, and an end connected to a minimum diameter portion of the tapered cylindrical body 2 and having an opening 3a at a central portion. A screw protector for a steel pipe tube end, which is composed of a plate 3 and an elastic ring-shaped seal member 4 arranged so as to contact the inner surface 3b of the end plate 3 and the inner peripheral surface 2b of the tapered cylindrical body 2. 1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to high pressure water applied to a male screw portion from a gap between a screw protector for protecting the male screw portion of the steel pipe end and a screw tip portion of the steel pipe end when performing a water pressure test of the steel pipe. The present invention relates to a screw protector for a steel pipe pipe end (hereinafter simply referred to as a screw protector) capable of preventing the male screw portion of the pipe end from rusting when invading.

[0002]

2. Description of the Related Art A steel pipe refining line consists of a thread cutting process at both ends of a steel pipe, a screw protector installation process at one end of a steel pipe, a coupling installation process at another steel pipe end, a coupling tightening process, and a hydraulic test. It has a line structure that can be performed consistently in order.

When a water pressure test is performed on a steel pipe, a screw protector is attached to the threaded portion of the steel pipe in this way so that the threaded portion at one end of the steel tube to which the coupling is not attached is not damaged. There is, however, JP-A-4-82492.
The conventional screw protector disclosed in Japanese Patent Publication is composed of a tubular body having an internal thread portion on the inner peripheral surface that is screwed into the male thread portion of the steel pipe end, and a lid attachable to the end portion of the tubular body. However, since it only serves to protect the male thread portion of the steel pipe pipe end during transportation, there are the following problems.

That is, when the above-mentioned conventional screw protector is attached and the lid is removed to perform a water pressure test, high-pressure water penetrates through the gap between the screw protector and the screw tip of the steel pipe, and the screw protector is introduced. There is a problem that high-pressure water remains between the end surface of the screw and the end surface of the screw and rusts.

However, when a screw of a type in which a seal portion is not formed in the vicinity of the screw tip, such as the conventional male screw, is processed into the steel pipe end, even if the screw end surface rusts, the screw The performance as a joint did not deteriorate.

In recent years, a type of screw having a seal portion near the tip of the screw has been developed and has come into general use. Along with this, there has been a demand for preventing rust from being generated in the vicinity of the screw tip so as not to impair the sealing property.

In order to meet such a demand, a water pressure test is performed in the state of the raw pipe before thread cutting, and then thread cutting-
There are a method of adjusting the steel pipe in a process of attaching a screw protector, a coupling, and a fastening of the coupling, and a method of washing the screw portion immediately after the water pressure test to remove water.

Of these, the former method is not accepted by some customers from the viewpoint of guaranteeing the pressure resistance of threaded joints, and cannot be applied to all of them, and the operation is similar to batch processing due to the configuration of the steel pipe adjusting line. There is also a problem that the work becomes complicated, and it becomes necessary to temporarily place the steel pipe temporarily, and the cost thereof becomes enormous.

[0009]

Therefore, it is necessary to provide a screw protector and a screw protector that prevents high pressure water from entering from the screw tip even when a water pressure test is performed after the process of thread cutting-attaching the screw protector. However, there has been no such screw protector in the past.

The present invention has been made in order to solve the above-mentioned problems of the prior art. Even if a water pressure test is carried out after the screw protector is attached, the high pressure water will not be removed by the screw protector and the screw tip. It is an object of the present invention to provide a screw protector for a steel pipe pipe end that does not penetrate from the end face of the seal portion of the steel pipe.

[0011]

DISCLOSURE OF THE INVENTION A screw protector for a steel pipe tube end according to the present invention is a taper cylinder body having an inner peripheral surface provided with a female screw to be engaged with a male thread of the steel pipe end, and a taper cylinder body. It is composed of an end plate connected to the small-diameter portion and having an opening in the center, and an elastic ring-shaped seal member arranged so as to contact the inner surface of the end plate and the inner peripheral surface of the tapered cylindrical body. It is a thing.

When the female screw of the screw protector at the end of the steel pipe is screwed into the male screw of the steel pipe and the screw protector is screwed in,
Finally, the ring-shaped sealing material of the screw protector is sandwiched between the end surface of the male screw portion of the steel pipe and the inner surface of the end plate of the screw protector.

After mounting the screw protector on the steel pipe in this way, a water pressure test is conducted by applying water pressure to the inner surface of the steel pipe. When water pressure is applied to the inner surface of the steel pipe, water pressure is also applied to the ring-shaped sealing material. Therefore, the ring-shaped seal material sandwiched between the end surface of the male thread of the steel pipe and the inner surface of the end plate of the screw protector is even stronger with the end face of the male thread of the steel pipe, the inner surface of the end plate of the screw protector, and the tapered cylinder. It is pressed against the peripheral surface to close the gap.

Therefore, at the time of the water pressure test, water does not enter the male screw portion of the steel pipe and rust the male screw seal portion.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described with reference to FIGS. Fig. 1 is a vertical cross-sectional view of a protection tool for a steel pipe end, Fig. 2 is a vertical cross-sectional view of a steel pipe during a hydraulic test, and Fig. 3 is a vertical cross-section of a protection device for a steel pipe end and a male screw portion of the steel pipe end during a hydraulic test. It is a figure.

This steel pipe pipe end screw protector (protector)
As shown in FIGS. 1 and 3, reference numeral 1 denotes a tapered cylindrical body 2 having an inner peripheral surface provided with an internal thread 2a to be engaged with an external thread of a steel tube.
And an end plate 3 which is connected to the smallest diameter part of the tapered cylindrical body 2 and has an opening 3a in the central part, and an inner surface 3b of the end plate 3 and an inner peripheral surface 2b of the tapered cylindrical body 2. It is composed of the ring-shaped sealing material 4 arranged.

The water pressure test of the steel pipe is carried out as shown in FIG. That is, the male threads of both ends of the steel pipe 21 (only one end of the pipe is shown in FIG. 2) are screwed into the female screws 2a of the screw protector 1 of the steel pipe end to form the screw protector 1 of the steel pipe end. As shown in FIG. 3, the ring-shaped sealing material 4 comes into contact with the end surface 21b of the tube end sealing portion of the steel tube 21 and is screwed in until it is deformed to some extent. Then, the headstock 22 is attached to both ends of the steel pipe 21, and the steel pipe 21 and the headstock 2 are attached.
Water is applied to the packing 23 between the two and the seal to seal it, and then the high pressure water 24 is supplied into the headstock 22. The high-pressure water 24 supplied into the headstock 22 enters the steel pipe 21 through the opening 3a of the end plate 3 of the screw protector 1 at the steel pipe end, and water pressure is applied to the inner peripheral surface 21a of the steel pipe 21.

Water pressure is also applied to the ring-shaped sealing material 4 of the screw protector 1 at the end of the steel pipe at the same time.
Since the recessed portion 4a is provided at the center of the ring-shaped sealing member 4, the ring-shaped sealing material 4 is attached to the end face 21b of the pipe end seal portion of the steel pipe 21 and the inner surface of the end plate 3 of the screw protector 1 of the steel pipe end due to the water pressure applied to the recessed portion 4a. 3b and the inner peripheral surface 2b of the tapered cylindrical body 2 are strongly pressed, and the high pressure water 24 causes the end surface 2 of the pipe end seal portion of the steel pipe 21.
1b and main seal portion 21c (section L in FIG. 3)
Do not get into it.

The material of the ring-shaped sealing material 4 of the screw protector 1 at the end of the steel pipe may be any commercially available material as long as it can withstand the high pressure of the water pressure test.

Further, the tapered cylindrical body 2 and the end plate 3 may be connected to each other by welding or the like, or the tapered cylindrical body 2 and the end plate 3 may be integrally formed.

[0021]

EFFECTS OF THE INVENTION According to the present invention, high-pressure water does not enter during a water pressure test to rust the main seal portion and the end surface of the seal portion provided at the end of the steel pipe, and the sealing property of the male screw portion provided at the end of the steel pipe is prevented. Can be kept at a high level.

Further, the reaction force of the ring-shaped sealing material pressed by the end face of the male screw can prevent the screw protector from being loosened due to vibration, impact force or the like during transportation of the steel pipe.

Further, since the loosening of the screw protector can be prevented, foreign matter such as sand intrudes between the male screw end surface and the screw protector during transportation of the steel pipe to damage the male screw end surface,
It is also possible to prevent rainwater from penetrating and generating rust on the end surface of the male screw, impairing the sealing performance.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view of a protector for a pipe end of a steel pipe.

FIG. 2 is a vertical cross-sectional view of a steel pipe and a male screw portion of a steel pipe end during a water pressure test.

FIG. 3 is an enlarged vertical cross-sectional view of a protector for a steel pipe pipe end and a male screw portion of the steel pipe pipe end during a water pressure test.

[Explanation of symbols]

 1 Screw protector for steel pipe end 2 Tapered cylindrical body 2a Internal thread of tapered cylindrical body 2b Sealing material of tapered cylindrical body Inner peripheral surface at fitting position 3 End plate 3a End plate opening 3b End plate inner surface 4 Ring-shaped sealing material 4a Recess of ring-shaped sealing material

Claims (1)

[Claims] 1. A tapered cylindrical body having an inner peripheral surface provided with an internal thread for screwing with a male external thread of a steel tube, an end plate connected to a minimum diameter portion of the tapered cylindrical body, and having an opening in a central portion, A screw protector for a steel pipe tube end, comprising: an elastic ring-shaped seal member arranged so as to contact the inner surface of the end plate and the inner peripheral surface of the tapered cylindrical body.