JPS58182550A - Pig for flaw detection of pipeline - Google Patents

Abstract

PURPOSE:To make flaw detection over the entire surface of a pipe easy, by connecting plural pieces of single pig bodies wherein electronic circuits, etc. having a detection function, a calculation function, a memory function, etc. are contained separately, freely flexibly to each other and constituting the same movably in the pipeline. CONSTITUTION:The 1st single pig body 2A is provided with a sliding ring 8 of a small sliding resistance around the same so as to be moved together with the fluid in a pipeline 1 and contains therein a motor 9 for rotating the other single pig bodies 2B-2D and a battery 10. The 2nd body 2B is provided with an ultrasonic probe 12 on the side surface and has an electronic circuit 13 for detection internally. The 3rd body 2C is provided internally with an electronic circuit 15 for calculation. Further, the 4th body 2D is provided with a sensor 17 for position detection at the rear end and has an electronic circuit 18 for memory internally. These bodies 2A-2D are connected flexibly and are moved by the fluid flowing in the pipeline 1, whereby the entire surface of the pipe is scanned and is detected of any flaw.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a flaw detection vig that detects flaws in a pipe while moving inside the pipeline.

For example, in the case of pipelines used in offshore oil production lines and various plants, it is best to perform flaw detection on pipelines after long periods of use.

, is very effective.

The present invention detects flaws in such pipelines by using a flaw detection vig that moves along the inside of the pipeline. When ultrasonic waves are incident on the inner surface in a non-perpendicular direction, if there is a scratch on the pipe, the reflected wave from the scratch will be detected by the above probe, but if there is no scratch, such reflected waves will be detected. is not detected, and the waves reflected from the inner and outer surfaces of the pipe do not return in the direction of the probe, except for those that are initially reflected from the pipe's internal force. Therefore, the presence or absence of the reflected waves can be used to detect the presence of flaws. This is what I am trying to do.

Therefore, the flaw detection pig of the present invention is equipped with an ultrasonic detector that injects ultrasonic waves in a non-perpendicular direction to the inner surface of the pipe at regular minute intervals and detects the reflected waves. An electronic circuit provided with a probe and used to obtain a signal indicating the presence or absence of a flaw in the pipe based on the reflected wave thereof;
and a memory circuit for storing the information.

Embodiments of the present invention will be described in detail below with reference to the drawings.

The embodiment shown in FIG. 1 is applied to, for example, a relatively small diameter pipeline such as an offshore oil production line.
A plurality of pigs are connected in a bendable manner in the pipeline 1,
A buffer ring 4 is still attached around it. Other suitable structures may be used to connect the individual pigs, but it is preferable that the ring 4 is made of a material that has a cushioning effect and at the same time has low sliding resistance against the inner surface of the pipe.

Airtight chambers 58 to 5D for accommodating flaw detection equipment are provided inside each of the capsule-shaped Vig units 2A to 2D. Among these chambers, chambers 5B to 5D are communicated with each other through communication holes 7B to 7C through which signal lines 6 are inserted, and necessary signals are exchanged between required signal processing elements through signal lines 6. .

In order to suppress rotation due to fluid pressure and reaction force due to the rotation of the motor 9, but to slide as easily as possible in the direction along the pipeline 1, it is formed so as to contact the inner surface of the pipe with an appropriate pressure contact force. Ru.

Note that instead of the motor 9, a structure in which the VIG units 2B to 2D are rotated using fluid pressure in a pipeline, or other appropriate means may be adopted.

A universal joint 3 is attached to the rotating shaft 11 of the motor 9.
The single pig 2B connected via A is provided with an ultrasonic probe 12 on its side, and the single pig 2D connected to its internal groove is provided with a position detection sensor 17 at its rear end. An internal chamber 5D houses an electronic circuit 18 such as a memory circuit, which will be described later, and a battery 19.

The ultrasonic probe 12 installed on the single pig 2B makes ultrasonic waves incident on the inner surface of the pipe 1α in a non-perpendicular direction, and as long as there are no scratches on the pipe lα, the ultrasonic probe 12 detects the reflected waves from the outer surface of the pipe, etc. This is to prevent it from returning to child 12,
Therefore, as shown in FIG. 2, the ultrasonic wave is disposed at a position offset from the center of the pipe so that the projection direction of the ultrasonic wave is inclined with respect to the inner surface of the pipe.

Therefore, it moves in a spiral shape with respect to the inner surface of the pipe, so flaw detection can be performed without scanning the entire surface of the pipe.

Next, the structure and operation of the pipe flaw detection device will be explained based on FIG.

The pulser circuit is for projecting ultrasonic pulses from the ultrasonic probe 12 at fixed minute time intervals, and the ultrasonic pulses emitted from the ultrasonic probe 12 by driving this pulser circuit are Since the ultrasonic probe 12 is arranged so as to be incident in a non-perpendicular direction to the inner surface of the pipe,
As shown in FIG. 2, if there is a flaw 20 on the pipe, the ultrasonic probe 12 is damaged.
0, R1 is a reflected wave on the inner surface of the pipe, and R2 is a reflected wave on the flaw 20. These reflected waves are sent to the gate circuit (II) through the Lember circuit shown in Figure 3.
This gate circuit (I), as shown in FIG. 4 (6),
The above reflected wave island based on the signal from the pulsar circuit etc.

) (2 is expected to be detected.The counter circuit is configured to open the gate only while it is expected that 2) is detected. The clock starts counting by the wave R1, and the counting is started by the next signal, that is, the reflected wave, and the counting circuit of this counter circuit is reset for each count by the reset signal from the pulser circuit. The counted value of the counter circuit is compared with the set value, and if the counted value is smaller than the set value, the gate circuit (II) is opened and information regarding the scratches and the position detected by the position detection sensor 7 and the position detection circuit are opened. It sends position information to the memory circuit.

The position detection sensor 17 and the position detection circuit are for detecting the position of the pig in the pipeline,
For example, the method previously proposed in Japanese Patent Application No. 57-3725 can be used. In this method, a pipe (1) is provided with a transducer through which a moving body runs, and this transducer (21) emits a bass-like sound wave or ultrasonic wave, and the pig transmits a sound wave or ultrasonic wave. While repeating this transmission, the position detection sensor and position detection circuit in the pig detect the sound waves or ultrasonic waves and measure the time interval, thereby calculating the distance from the transducer to the pig and the position of the pig. It is detected as information.

The information regarding the damage on the pipe detected by the counter circuit and the position information detected by the position detection circuit are sent in correspondence to the memory circuit and stored therein. The contents of this memory circuit are read after the pig is taken out of the pipeline, and if the pipe is damaged by this, a timer or the like that sequentially outputs a time signal is used instead of the device described above. Location can also be estimated by time.

As is clear from the detailed description above, according to the flaw detection pig of the present invention, by transporting it with fluid flowing in the pipeline, flaw detection can be performed by scanning the entire surface of the pipe. It is particularly effective for periodic inspections of pipelines, etc. Unfortunately, in the present invention, each Pig is made into a module by accommodating electronic circuits each having a detection function, arithmetic function, memory function, etc., and thereby collects various information in the pipeline. For 111@II pipeline, 1α00.pipe, 2A
~2D...Vig single unit, 12...Ultrasonic probe, 13
, , 15 , 18...Electronic circuit, 20...Scratch.

Claims (1)

[Claims] 1. By connecting a plurality of individual pigs in a flexible manner, an ultrasonic probe is installed to transfer and inject the fluid flowing through the pipeline and detect the reflected waves, and to detect defects in the pipe based on the reflected waves. A VIG for pipeline flaw detection, characterized in that it is equipped with an electronic circuit for obtaining a signal indicating the presence or absence of a crack, and a memory circuit for storing the signal.