JP3272651B2 - Inspection method of buried piping - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of inspecting a pipe buried underground, and more particularly to a method of inspecting a pipe through which contents such as crude oil, which easily loses its thickness, flow.

[0002]

2. Description of the Related Art Pipes such as crude oil pipes are sometimes buried due to a problem of an installation place such as crossing a road. The buried piping may be corroded or eroded by the contents circulating or by the buried environment. For this reason, it is necessary to inspect the soundness of the piping every certain period. In addition, the life of the buried pipe is difficult to predict because the environment such as the temperature is different from that on the ground even if the same contents as the pipe on the ground flow.

Conventionally, such pipe inspection is performed by digging up a buried pipe and inspecting it like a normal pipe, or by inserting a special sensor into a buried pipe and inspecting it. I was

[0004]

However, the inspection by excavating the pipe requires the civil engineering work to excavate the pipe for the inspection, and the construction period and cost are increased. Also,
In an inspection with a special sensor inserted, piping cannot be used during the inspection period, and applicable piping is limited.

[0005] In particular, when a buried pipe circulates a dangerous substance such as petroleum or the like, high reliability is required because the leakage has a large effect on the environment. Furthermore, when the content is crude oil, unlike refined petroleum, it contains a large amount of sulfur and water and corrosive on the inner surface of the pipe, so that particularly frequent inspection is required.

An object of the present invention is to solve such a problem, and an object of the present invention is to provide a method for inspecting a buried pipe simply and with high reliability.

[0007]

SUMMARY OF THE INVENTION A method for inspecting a buried pipe according to the present invention comprises burying a pipe in the ground, excavating the pipe, detecting a thinned portion of the pipe, and controlling the local thickness of the pipe. Attach a thickness sensor that can output the corresponding signal to the thinned part,
Thereafter, the pipe is buried in the ground, and after burying the pipe, the thickness of the thinned portion is measured by the output signal of the thickness sensor.

[0008]

Operation and effect of the present invention A portion in a pipe which is easily reduced in thickness can be detected by inspecting after using it for a certain period of time.
This portion is liable to be reduced in thickness thereafter due to corrosion or the like.
Therefore, by continuously measuring the thickness reduction of this portion, it is possible to inspect and predict leakage, breakage, and the like of the pipe. At this time, since the thickness measurement at this location is performed by a thickness sensor buried together with the pipe, it is not necessary to dig the pipe every time the inspection is performed, and it is possible to continuously grasp the thickness reduction.

Therefore, it is possible to easily and accurately inspect a buried pipe, particularly a pipe through which contents such as crude oil which easily corrodes and wears the inner surface of the pipe.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS [Piping] The present invention is effectively used when a pipe to be used is made of an iron-based material such as carbon steel. The contents of the pipe are particularly suitable when the pipe is easily corroded and eroded, specifically, when the pipe is crude oil.

[Embedding] The present invention is applied to inspection of a portion of a pipe buried (buried) in the ground. Piping is also applicable when partially buried, such as when the lower half is buried in soil.

[Excavation of Piping] In the present invention, after burying a pipe and using it for a certain period, the pipe is dug to inspect a thinned portion of the pipe. The period of use is set to a period that is equal to or longer than the period in which the wall thickness of the pipe is expected to advance to a measurable extent, and that the pipe can be used safely. Usually, it is about one to ten years. To increase the accuracy of the inspection,
All the buried sections are excavated, but it is also possible to excavate only a part and inspect the thinned portion. It is not necessary that all sections be dug at the same time.

[Detection of Thinned Portion] In the present invention, the thickness of the dug pipe (thickness of the pipe) is measured to detect a thinned portion (thickened portion). The thinned portion may be located at one place in one pipe to be inspected, or a plurality of regions where the thickness is relatively reduced may be selected. In order to increase the accuracy of the inspection, the thickness of the entire surface of the pipe is measured to detect the thinned portion. However, it is also possible to measure only the region where the thinning is clearly expected to proceed. In a crude oil pipe arranged substantially horizontally, wall thinning usually occurs in the lower half of the pipe, so that only that region may be measured.

As a method of measuring the thickness of the pipe (the thickness of the pipe), a method utilizing reflection of ultrasonic waves in the thickness direction of the pipe, a method of measuring from absorption of electromagnetic waves such as γ rays, and the like can be used. it can. Since a large area can be measured efficiently, a method utilizing reflection of ultrasonic waves is preferably used.

[Thickness Sensor] In the present invention, a thickness sensor is attached to the thinned portion, and the pipe is buried again. In general, a plurality of positions for mounting the thickness sensor are selected from the thinned portion. The thickness sensor outputs a signal corresponding to the pipe thickness of the thinned portion. The signal can be retrieved on the ground. A sensor signal unit that performs signal processing, arithmetic processing, and the like on the sensor signal may be buried or installed on the ground. In general, one sensor signal unit can handle a plurality of thickness sensors.

As the thickness sensor, an ultrasonic probe is used because it is easy to attach and has high measurement accuracy.
Thereby, the ultrasonic vibration is transmitted and received into the pipe, and the local thickness is detected. Usually, an ultrasonic flaw detector is used as a sensor signal unit for an ultrasonic probe.

[Judgment of Inspection] The pipe to which the thickness sensor is attached is buried, and then the pipe is continuously used. By using the thickness sensor, the thickness of the buried pipe can be continuously measured. If the thickness falls below a predetermined value, or if there is an abnormal change in the thickness over time (for example, a sharp decrease in the thickness), it may be necessary to dig up again to perform inspection and repair. it can.

[Use in Combination with Other Inspections] The present invention may be used in combination with other inspection methods. In this inspection method, when the thickness sensor is fixed closely to the outside of the pipe, it is difficult to detect corrosion etc. occurring on the outside of the pipe, and it is necessary to perform sufficient anticorrosion treatment on the outside of the pipe .

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The inspection method of the present invention will now be described with reference to FIG.
This will be specifically described with reference to FIG.

The pipe to be inspected is a pipe 1 for sending crude oil, and is composed of a buried pipe section 3 buried underground 2 and a ground pipe section 4 continuous therewith. After laying a new pipe, the pipe is used in a normal state for a predetermined period (for example, 5 years), and then the soil around the buried pipe portion 3 is dug to expose the pipe so that it can be inspected. The inspection of the buried piping portion 3 is performed by using the ultrasonic flaw detection method. As a result, the inner wall of the pipe is reduced in thickness, and the thickness of the thinned portion 5 is locally reduced as compared with other portions.
Find out. At this time, any parts that are already at risk of leakage or damage will be repaired.

A thickness sensor 6 is fixed to the thinned portion 5. As the thickness sensor 6, an ultrasonic probe is used, and a waterproof treatment or the like is performed so as to operate stably even in the ground. The signal from the thickness sensor 6 is taken out by a wiring 8 to a joint box 9 provided on the ground for connection to a sensor signal unit 7 composed of an ultrasonic flaw detector installed on the ground. After sufficient anticorrosion treatment is performed on the outer surface of the buried pipe portion 3, the buried pipe portion 3 is buried again in the ground.

After the embedding, normal use is continued, and the thickness of the thinned portion 5 is measured by the thickness sensor 6 at regular intervals (for example, one year) to confirm the soundness of the embedded pipe. The measurement is performed via the joint box 9 through the sensor signal unit 7.
And the thickness sensor 6 are connected.

According to this inspection method, the soundness of the pipe can be confirmed by a simple operation without frequently excavating the buried pipe portion 3.

[Brief description of the drawings]

FIG. 1 is a diagram for explaining a method of inspecting a crude oil pipe according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Piping 2 Underground 3 Buried piping part 4 Ground piping part 5 Thinning part 6 Thickness sensor 7 Sensor signal part 8 Wiring 9 Joint box

──────────────────────────────────────────────────続 き Continued on the front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) G01B 5/00-7/34 102 G01B 11/00-11/30 102 G01B 15/00-21/32 G01N 21/00-23/227 G01N 29/00-29/28

Claims (1)

(57) [Claims] An ultrasonic probe as a thickness sensor capable of detecting a thinned portion of a pipe and outputting a signal corresponding to a local thickness of the pipe by burying the pipe in the ground and then excavating the pipe . A method of inspecting a buried pipe, in which a child is attached to the thinned part, and then the pipe is buried underground, and then the thickness of the thinned part is measured by the output signal of the thickness sensor.