JPS5838722B2 - Piping penetration length measurement method - Google Patents

Description

[Detailed description of the invention] This invention relates to a method for measuring pipe insertion length.

The joints of gas piping are constructed to be able to respond to changes in the environment to some extent by using expansion joints such as dresser joints and sleeve joints, but there is a risk that the pipe connections may become separated and cause gas leakage, so they are generally not It is necessary to inspect and repair.

In that case, it is necessary to know how far the end of the pipe is inserted into the fitting without disassembling the pipe connection.
Regarding this measurement method, methods using radiation and methods using ultrasound have been considered.

However, methods that use radiation have problems in handling and on-site use of radiation, such as the need for qualified personnel, and the inability to obtain measurement results early (method of photographing on film); Although it is not necessary, there are drawbacks such as the fact that the length of the piping to be inserted can only be obtained with an accuracy of centimeters (method using a counter) because the radiation source part and the counter part have a certain size.

On the other hand, compared to the above-mentioned methods, the method using ultrasound does not require qualifications for the measurer, allows early acquisition of measurement results, allows for immediate action, is easy to operate, and does not require skill, etc. Although this method was advantageous in that it required knowing the sound velocity in the pipe member.

In other words, the sound speed is determined by Young's modulus, density, and Poisson's ratio, and is related to temperature and piping installation conditions and conditions, so the sound speed must be measured each time, which is extremely inefficient for on-site measurement work. Moreover, it was complicated and lacked practicality.

Therefore, an object of the present invention is to provide a pipe insertion length measuring method that can quickly and easily measure the length regardless of installation conditions.

FIG. 1 shows one state in which the method of the invention is used.

That is, the object to be measured is a pipe 2 connected by a dresser joint 1, and the insertion length X of the end of the pipe 2 into the inside of the dresser joint 1 is to be measured.

The measurement is carried out by setting the ultrasonic angle probe 3 at two positions on the surface collapse of the pipe 2, separated by a certain distance l in the length measurement direction, and at each position, the length measurement direction is adjusted as shown in Fig. 2. The wave is emitted into the piping member with a constant refraction angle, and the reflected wave from the tube end 4 is received, and the round trip propagation time t1. Measure t2 (read values A, B on the cathode ray tube screen).

).

In this case, two simultaneous relational expressions are obtained from each measurement result.

t 1 X C

From these two equations, the speed of sound C and the angle of refraction α can be eliminated, is obtained.

From this equation, by determining the installation position of the probe 3 and measuring the reciprocating propagation time of the ultrasonic waves, the pipe insertion length X can be determined without knowing the sound speed related to the state of the pipe installation site.

In addition, there are cases where one ultrasonic angle probe performs two measurements, and
There are cases where two pieces are used for measurement, and instead of a dresser joint, it can also be applied to an expansion joint, such as a sleeve joint, in which the pipe end and the outer fitting part of the joint slide against each other.

Below is a measurement example.

Measurement example 1: Pipe diameter 200 mm, see Figure 3 (1) 1 = 100 L = 56 t-1,64, t2 = 2.52 - Also, since this device is accurate in measuring distance, Figure 4 As shown in FIG. 2, it can also be used to confirm the position of a joint portion 6 of a buried cast iron pipe 5.

That is, by using this method by exposing one joint part of a pipe through excavation, it is more accurate and has a higher probability than searching for a joint position using a known pipe length from the ground.

7 is earth. As described above, the piping insertion length measuring method of the present invention measures the round trip propagation time using ultrasonic probes placed at regular intervals on the piping surface, so it is quick, easy, and requires no knowledge of the sound velocity of the member to be measured. This method has the advantage of being able to measure the length accurately and being highly practical.

[Brief explanation of drawings]

Fig. 1 is a plan view of a pipe joint for explaining the method of this invention, Fig. 2 is an enlarged sectional view of the main part thereof, Fig. 3 is a partial sectional view of the pipe to be measured, and Fig. 4 is a diagram of the method of this invention. It is a location diagram showing another state of use. 1...Dresser joint, 2...Piping,
3... Ultrasonic angle probe.

Claims (1)

[Claims] 1 Ultrasonic angle probes are installed at the first and second positions on the surface of a pipe whose end is inserted into an expansion joint, and ultrasonic waves are emitted toward the end of the pipe until it returns by reflection at the end surface of the pipe. A pipe insertion length measuring method characterized by measuring first and second reciprocating propagation times t1 and t2, and determining the length X of a pipe inserted into an expansion joint using the following equation.