Method for measuring bending angle of pipe bend for oil and gas transportation

In order to overcome the problems of many tools, complicated measurement steps, many human interference factors, time-consuming and labor-consuming, and large measurement errors in the traditional pay-off method to measure the bending angle of bends, a new type of bending with an electronic level measuring instrument as the core device was designed. Pipe bending angle measuring device. The structure and measuring method of this new type of bending angle measuring device for bends are introduced. This measurement method uses an electronic level measuring instrument to directly read the included angle between the straight pipe section at both ends of the pipe bend and the ground plane. After a simple calculation, the bending angle of the pipe bend can be obtained. The problem of inaccurate measurement results caused by factors, etc., provides new ideas and methods for accurately measuring the angle of the pipe bend.

With the rapid development of my country’s economy, long-distance pipelines, as one of the most economical, safe and uninterrupted long-distance transportation tools for oil and natural gas, have achieved considerable development in the past ten years, and this kind of development momentum It will continue in the future [1-6]. With the continuous increase of the laying mileage of long-distance pipelines, the internal performance requirements of steel pipes for long-distance pipelines continue to increase in the industry. At the same time, higher requirements are put forward for the dimensional accuracy of the steel pipes [7-12].
Pipe bends are an important part of long-distance pipeline construction, and are used in undulating areas such as mountainous areas, hills and rivers. Its role is mainly in two aspects: one is to meet the design requirements for the flexible laying of long-distance pipelines [13], and to prevent thermal expansion and contraction from damaging the pipeline; the other is to change the direction of the pipeline to meet the requirements of changing terrain.
Among the geometric dimensions of the pipe bend, the bending angle is the most important parameter that directly reflects the function of the pipe bend. If the bending angle error is too large, it will directly affect the quality of the on-site construction, resulting in difficulties in matching, increased stress in the weld, and even bending The pipe is scrapped and cannot be used, which seriously affects the construction quality and progress.

Disadvantages of the pay-off method

The previous design of bends is 3° as the first gear, and the standard error requirement is ±1° (see 8.7.4 in the standard SY/T5257-2012 [14]). However, with the improvement of construction quality requirements, the design of the pipe bend has been increased to 1°, and the error requirement has also increased to ±0.4° (see the gas transmission pipeline project of the Jingxi No. 1 and No. 2 and Jingxi No. 3 natural gas pipelines in Shaanxi Province Technical specifications [15]).
At present, the measurement method for the bending angle of the pipe bend with straight pipe section often adopts the measurement method given in SY/T5257—2012 (also called the pay-off measurement method), using angle ruler, platform, 2000mm steel ruler and square ruler as measuring tools , put the pipe bend on the platform, and then use a square ruler to find N points (N≥6) on the straight pipe sections at both ends of the pipe bend and project them on the platform (as shown in Figure 1); then move the pipe bend from the platform Take it away from above, find the center lines of the straight pipes at both ends according to these points, and intersect at point A, and then use angle ruler or trigonometric function calculation method to measure the bending angle α of the pipe bend.
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Fig.1 Schematic diagram of existing bending angle measurement method
The process of the pay-off method to measure the angle of the pipe bend is shown in Figure 2. It can be seen from Figure 2 that the measurement method uses a variety of tools, complex measurement steps, many human interference factors, time-consuming and labor-intensive, and measurement errors. In response to this problem, the author designed a new measuring device to measure the bending angle of the pipe bend.
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Fig. 2 The process of measuring the angle of the pipe bend by the pay-off method

Design of the measuring device for bending angle of bend

Based on years of experience, the author has designed a measuring device for the bending angle of the pipe bend. Its structure is shown in Figure 3. The device is mainly composed of an electronic level measuring instrument, a reference base and a power supply. The reference base includes a rectangular platform and 4 outriggers equipped with travel switches. The rectangular platform is 203.2mm long, the legs are 50.8mm high and 25.4mm wide, and the distance between the two legs arranged along the width of the rectangular platform is 101.6mm. One travel switch is set at the bottom of each leg, and four travel switches are connected in series at both ends of the power supply to form a measurement trigger circuit (as shown in Figure 4); the electronic level measuring instrument is set on the upper part of the rectangular platform and is connected in series with the measurement trigger circuit.

The working principle of the bending angle measuring device of the pipe bend: when the legs of the reference base are in full contact with the straight pipe section of the pipe bend, all 4 travel switches are closed, the measurement trigger circuit is connected, and the electronic level measuring instrument starts to measure and display the measurement angle.

20210107210331 37597 - Method for measuring bending angle of pipe bend for oil and gas transportation

Figure 3 Schematic diagram of the structure of the bending angle measuring device of the elbow

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Fig. 4 Working principle of the measurement trigger circuit in the measurement device

Measuring method of bending angle of bend

The measurement process of the bending angle of the pipe bend is shown in Figure 5. The measurement steps are as follows:

  • (1) Use a crane and a sling to hoist the pipe bend to be tested, with the aid of the gravity of the pipe bend to be tested, make the plane formed by the centerline of the pipe bend to be tested perpendicular to the horizontal plane, and make the bending section be located below;
  • (2) Select straight pipe section 1 and straight pipe section 2 at the equal heights of the straight pipe sections on both sides of the curved section;
  • (3) Place the leg of the bending angle measuring device of the pipe bend on the straight pipe section 1, so that the travel switch on the bottom is close to the pipe wall, the travel switch is closed, and the angle value of the electronic level measuring instrument is read; measure the first straight pipe section The two positions of the highest point A1 and the lowest point A2 of the same circle, obtain the angle α1 and α2;
  • (4) In the same step (3), measure the highest point B1 and the lowest point B2 of the same circumference of the straight pipe section 2 to obtain the angles β1 and β2;
  • (5) According to the angle measured in step (3) and step (4), calculate the pipe bend angle α according to formula (1):

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Fig. 5 Schematic diagram of the bending angle measurement process of the pipe bend

Conclusion

The pay-off method to measure the angle of the pipe bend is low in efficiency and greatly affected by human factors. Measurement techniques, measuring equipment accuracy, and angle calculation errors can cause the actual angle of the pipe bend to deviate from the true angle, or even exceed the standard deviation range, resulting in unqualified bends The outflow of pipe products will ultimately affect the construction quality of the long-distance pipeline laying site. Therefore, controlling the outflow of bends with out-of-tolerance bend angles is of great significance to improve the quality of long-distance pipeline construction on site.
The bend angle measuring device with a horizontal measuring instrument and a base is used to measure the pipe bend angle, which can greatly improve the inspection efficiency and measurement accuracy of the pipe bend angle measurement, meet the accuracy requirements of long-distance pipeline equipment under the new situation, and improve the long-distance pipeline construction quality of the pipeline.It can greatly improve the inspection efficiency and measurement accuracy of elbow angle measurement, meet the accuracy requirements of long-distance pipeline equipment under the new situation, and improve the construction quality of long-distance pipeline.
Author: CONG Shan1, LI Fuqiang2,3, WU Jinhui2,3

Source: Network Arrangement – China Pipe Bend Manufacturer – Yaang Pipe Industry Co., Limited (www.steeljrv.com)

(Yaang Pipe Industry is a leading manufacturer and supplier of nickel alloy and stainless steel products, including Super Duplex Stainless Steel Flanges, Stainless Steel Flanges, Stainless Steel Pipe Fittings, Stainless Steel Pipe. Yaang products are widely used in Shipbuilding, Nuclear power, Marine engineering, Petroleum, Chemical, Mining, Sewage treatment, Natural gas and Pressure vessels and other industries.)

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  • [15] 04-01 made by SPE-0800, technical specification of hot simmering bends for Jingxi first and second lines and Jingxi third line tie line engineering [S].
Summary
method for measuring bending angle of induction heating bend for oil and gas transportation - Method for measuring bending angle of pipe bend for oil and gas transportation
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Method for measuring bending angle of pipe bend for oil and gas transportation
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In order to overcome the problems of the traditional pay-off method for measuring the bending angle of the elbow, there are many tools, complicated measurement steps, many man-made interference factors, time-consuming and labor-intensive, large measurement errors, etc., a new type of bending with electronic level measuring instrument as the core device Tube bending angle measuring device.
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