JPH0312688B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for detecting a welded part of a pipe coated with a heat insulating material etc., which detects the position of a welded part of a pipe covered with a heat insulating material etc. It is an object of the present invention to enable the position of the welded portion to be detected.

In general, among multiple piping in each plant, for example, piping that must maintain a constant temperature of the internal circulating material, the circumference of the piping is covered with a heat insulating material, but the covered piping is circular. When a circumferential joint has a welded part, conventionally, when performing a material test to check for defects in the welded part and material deterioration of the pipe during use, or to detect the position of the welded part, Since all of the heat insulating material was peeled off, it was very time consuming and the piping could not be covered again with the peeled off heat insulating material, requiring new heat insulating material, which resulted in high costs.

This invention has been made with the above-mentioned points in mind, and includes a dolly running parallel to the length direction of the coated pipe having a welded portion of a circumferential joint, and a radiation line provided on the dolly so as to be movable up and down. A radiation source emits radiation to the peripheral edge of the pipe, a detector provided on the cart so as to be movable up and down in conjunction with the radiation source detects the radiation passing through the peripheral edge, and a detection signal of the detector is detected. Accordingly, there is provided a method for detecting a welded portion of a covered pipe, characterized in that a predetermined scanning position of the peripheral edge portion is detected, and a position of the welded portion is also detected.

Therefore, according to the method for detecting a welded part of coated piping of the present invention, a radiation source emits radiation to the peripheral edge of the coated piping, a detector detects the radiation transmitted through the peripheral edge, and the radiation from the detector is detected. By detecting a predetermined scanning position of the peripheral edge portion and also detecting the position of the welded portion of the piping using the detection signal, it is possible to easily scan the piping without peeling off the insulation material or other covering of the piping. The position of the weld can be detected.

Next, the present invention will be described in detail with reference to drawings showing one embodiment thereof.

First, in FIG. 1 showing a welded part detection device for coated piping, 1 is a coated pipe made of a steel pipe covered with a heat insulating material 1', and 2 is a coated pipe fixedly arranged on the heat insulating material 1' of the pipe 1. a rail plate on which a guide rail is formed; 3, a truck whose wheels are placed on the rails of the rail plate 2 and run parallel to the length direction of the pipe 1; 4, a support fixed to the truck 3; 5; 5' are formed integrally hanging from the left end and right end of the support body 4, respectively, and have bent parts 5a and 5' at the lower end, respectively.
The first and second holders 5a' are provided with vertical guide holes 5b and 5b', and 6 and 6' are the first and second holders provided at the left and right ends of the support 4, respectively.
The ball bearings 7, 7' are supported by both bearings 6, 6', respectively, and have vertical internal threads 7a, 7a' formed in their central parts, and sprockets 8, 8' integrally formed in their upper ends. first and second rotating bodies; 9 is a control motor that is fixed to the center of the support 4 and moves a mounting body, which will be described later, by a predetermined amount; 10 is a gear mounted on the rotating shaft of the motor 9;
11 and 11' are installed between the sprockets 8 and 8' and the gear 10, respectively, and transmit the rotation of the motor 9 to the sprockets 8 and 8'.
8' in the same direction, first and second chains;
12 and 12' are each formed with a thread at the upper end or the center, and the internal threads 7a and 7a of both rotating bodies 7 and 7' are respectively threaded.
1st and 2nd rods screwed into 7a', 13, 13'
are guide holes 5b and 5 of both holders 5 and 5', respectively.
The first and second mounting bodies 14 and 14', which are inserted through b' and fixed to the lower ends of both rods 12 and 12', are connected to the first and second guide grooves formed in both mounting bodies 13 and 13', respectively. , 15, 15' are both holding bodies 5,
5' and is fitted into both guide grooves 14, 14' to connect both rods 12, 12' and both mounting bodies 1.
3, 13', first and second guide bodies for preventing rotation;
16 is a first radiation source (hereinafter referred to as a first radiation source) that is attached to the lower end of the second attachment body 13' and emits radiation; 17 is attached to the lower end of the first attachment body 13 and emits radiation from the first radiation source 16; Detects the radiation of the first radiation source 1
A first detector 19 consisting of a scintillation counter, which together with 6 etc. constitute the scanning position detection means 18;
is a second radiation source (hereinafter referred to as the second radiation source) which is attached to the upper end of the first attachment body 13 and has the same structure as the first radiation source 16.
20 is a second detector consisting of a scintillation counter, and when the first radiation source 16 and first detector 17 are arranged at a predetermined scanning position on the lower peripheral edge of the pipe 1. is attached to the upper end of the second attachment body 13' so as to be disposed together with the second radiation source 19 at a predetermined scanning position on the upper peripheral edge of the pipe 1;
Detects radiation from the second radiation source 19, and detects radiation from the second radiation source 1
9 and the like constitute a welding portion detection means 21.

Next, FIGS. 2 and 3 showing both the detection means 18 and 21 will be explained.

In Figure 2, 22 is an AC 100V power supply;
3 is connected to the power supply 22 and transmits high voltage to the first detector 17
24 is an amplification unit that amplifies the detection signal from the first detector 17; 25 is a selection unit that selects the wave height of the amplified first detection signal to remove noise; 26 is a wave height a shaping section that shapes the waveform of the selected first detection signal; 27 is a gate;
8 is a count rate meter that counts the radiation dose based on the detection signal from the gate 27; 29 is an operation control unit that outputs a control signal to the motor 9 according to the radiation dose count value by the count rate meter 28; The motor 9 is actuated by the control signal, and both mounting bodies 13 and 1 are operated.
3' moves up and down, and the scanning position detection means 18 is constituted by the circuit shown in FIG. 2 and the first radiation source 16.

Further, FIG. 3 shows the welding part detection means 21, which, like the scanning position detection means 18, includes a power supply 22', a high voltage generation part 23', an amplification part 24', a sorting part 25', a shaping part 26', and a gate 27. ', a count rate meter 28', a second detector 20, and a second radiation source 19, and is configured so that the response speed of the welding part detection means 21 is shorter than that of the scanning position detection means 18. .

Prior to the detection of a predetermined scanning position of the upper peripheral edge of the pipe 1 by the second radiation source 19, the scanning position detection means 18 detects when the distance from the outer surface of the lower peripheral edge of the pipe 1 toward the center is changed. The relationship between the distance and the count value is obtained in advance by calculating each count value by the count rate meter 28, and among the calculated count values, the rate of change of the count value due to the difference in the wall thickness of the pipe 1 is calculated. Deriving a predetermined count value at the position of the largest predetermined distance, and outputting a control signal by the operation control unit 29 when the count value of the count rate meter 28 of the scanning position detection means 18 matches the derived count value. The operation control section 29 is set so that the operation stops.

Next, when detecting the predetermined scanning position, when the trolley 3 is slowly run along the rail plate 2 and both the detection means 18 and 21 are activated, the first detector 17 detects the lower peripheral edge of the pipe 1. When radiation passing through the section is detected and a detection signal is output, and the count value of the count rate meter 28 based on the detection signal is larger than the predetermined count value set in advance, the operation control section 29 causes the first It is determined that the scanning position by the radiation source 16 is a part close to the outer surface of the pipe 1 or a part of the heat insulating material 1' outside the pipe 1, and a control signal is output from the operation control unit 29 to the motor 9 to move both attached bodies. The motor 9 rotates in the direction of moving the wheels 13, 13' upward, and the rotation of the motor 9 is transmitted to the two rotating bodies 7, 7' via both chains 11, 11'.
7' rotates, both rods 12, 12' move upward, both mounting bodies 13, 13' move upward, the first radiation source 16 and the first detector 17 move upward, and the count rate meter 28 moves upward. When the count value is smaller than the predetermined count value, the operation control unit 29 causes the first
It is determined that the scanning position by the radiation source 16 is close to the inner surface of the pipe 1, and a control signal is output from the operation control unit 29 to the motor 9, so that the motor 9 rotates in the opposite direction to the above, and both mounting bodies 13 , 13' move downward.

Further, when the count value of the count rate meter 28 matches the predetermined count value set in advance, the operation control unit 2
9, it is determined that the scanning position by the first radiation source 16 is a predetermined scanning position, and the operation control unit 29
stops operating, the output of the control signal is stopped, the motor 9 is stopped, both mounting bodies 13 and 13' are placed in predetermined positions, and the first radiation source 16 and first detector 17 are connected to the pipe 1. The second radiation source 1 is disposed at a scanning position a predetermined distance from the outer surface of the lower peripheral edge toward the center.
9. A second detector 20 is disposed at a scanning position a predetermined distance from the outer surface of the upper peripheral edge of the pipe 1 toward the center, and radiation is emitted from the second radiation source 19 to the predetermined scanning position of the upper peripheral edge. The radiation transmitted through the upper peripheral edge is detected by the second detector 20, a detection signal is output from the second detector 20, and the count rate meter 28' of the welding part detection means 21 detects radiation based on the detection signal. While the amount is counted, the above-mentioned operation is repeated while the trolley 3 is running, and the radiation amount based on the detection signal from the second detector 20 is measured by the count rate meter 28' at each position in the length direction of the pipe 1. It is counted.

And if there is a welded part of the circumferential joint in pipe 1,
Since radiation is absorbed by the bead of the weld, the count at the weld becomes very small compared to the counts of the count rate meter 28' at positions other than the weld in the length direction of the pipe 1, and the count at the weld becomes very small. By reading the position in the length direction of the pipe 1 when the numerical value becomes small, the position of the weld is detected.

Therefore, according to the embodiment, the scanning position detecting means 18 detects a predetermined scanning position of the lower peripheral edge of the pipe 1, and the second radiation source 19 and the second detector 20 of the welding part detecting means 21 is placed at a predetermined scanning position on the upper peripheral edge of the pipe 1, and the second radiation source 1
9 emits radiation to a predetermined scanning position on the upper peripheral edge, and the position of the welded part is detected by the detection signal from the second detector 20. The position of the welded portion can be easily detected without peeling off the welded portion.

Furthermore, the scanning position detecting means 18 detects the position of the trolley 3.
Since the second radiation source 19 and the second detector 20 can be placed at a scanning position a predetermined distance from the outer surface of the upper peripheral edge of the pipe 1 toward the center even while the pipe is running, the thickness of the heat insulating material 1' The second radiation source 19 and the second detector 20 can always be disposed at the predetermined scanning position even if the angle varies, and the welded portion can be detected accurately.

In addition, radiation from both radiation sources 16 and 19 is transferred to the pipe 1.
Since the radiation is made to radiate to the peripheral edge of the pipe 1, even if the circulating material flows inside the pipe 1, it is possible to prevent the radiation from attenuating due to the circulating portion, and even when the circulating material is flowing, it is possible to prevent the radiation from attenuating the welded part. The position can be detected and the accuracy of the detection can be improved.

Note that in the above embodiment, the first and second radiation sources are used as radiation sources.
Two second radiation sources 16 and 19 were used, and two first and second detectors 17 and 20 were used as detectors, but one radiation source and one detector each,
A signal from the detector may be used to detect a predetermined scanning position and a welded portion.

[Brief explanation of drawings]

The drawings show an embodiment of the method for detecting welds in coated piping according to the present invention, and FIG. 1 is a partially cutaway front view of an apparatus for detecting welds in coated piping, and FIGS. 1 is a block diagram of the scanning position detection means and welding portion detection means in FIG. 1. FIG. 1... Covered piping, 3... Trolley, 16, 19...
1st, 2nd radiation source, 17, 20... 1st, 2nd
Detector.

Claims (1)

[Claims] 1. A cart is run parallel to the length direction of a coated pipe having a welded portion of a circumferential joint, and a radiation source provided on the cart so as to be movable up and down emits radiation to the peripheral edge of the pipe, and the radiation source A detector provided on the trolley so as to be movable up and down in conjunction with detects the radiation passing through the peripheral edge, and detects a predetermined scanning position of the peripheral edge based on the detection signal of the detector; A method for detecting a welded part of covered piping, the method comprising detecting the position of the welded part.