Analysis of the causes of cracks in the flattening test of welded steel pipes

Posted by BAOWI STEEL MANUFACTURING CO.,LTD on January 9th, 2025

Analysis of the causes of cracks in the flattening test of welded steel pipes
The quality of steel pipes determines the quality of the entire construction project to a certain extent. In the steel pipe process, in order to ensure the quality of steel pipes and meet the needs of users, it is necessary or required to strictly control the process quality during the production process, especially for the analysis and detection of steel pipe flattening test. The author conducts a simple analysis and discussion based on the causes of cracks in the welded steel pipe flattening test, hoping to effectively improve the physical quality of steel pipes through the analysis of the causes of cracks in welded steel pipes.
my country's energy construction has achieved rapid development and construction. The research and application of steel pipe production technology not only meets the needs of my country's oil and gas transportation, but also brings certain help to the development of various projects in the city. In the process of steel pipe flattening test, different needs have different requirements for steel pipe flattening test. At the same time, due to the different overall quality and service life depreciation of steel pipes, the construction efficiency is reduced during the overall construction process. This hinders the development of related construction industries and brings great difficulties to construction in the new era.
1. Factors affecting the flattening test results of welded steel pipes
(I) Influence of steel pipe material quality

For the overall material of steel pipes, in terms of quality, there are not only different degrees of restrictions on the physical and chemical aspects of steel pipes, but also the overall quality indicators of steel pipes are affected by the material quality to a certain extent. Therefore, in the process of flattening test of steel pipe quality, the overall type of steel pipe production process should be clearly controlled, the distribution of various chemical elements in the steel pipe should be clear, the degree of carbon content should be guaranteed under certain conditions, the good flexibility and ductility of the steel pipe in the production process should be guaranteed, the most basic construction characteristics should be guaranteed, and its processing quality should be guaranteed. For welded steel pipes for low-pressure fluid transportation, low-pressure fluid transportation welded steel pipes, also known as welded pipes, are welded steel pipes used to transport generally low-pressure fluids such as water, gas, oil and heating steam; steel pipes must meet the requirements of GB/T 3091-2008. According to the provisions of GB/T 3091-2008, resistance welded steel pipes with an outer diameter greater than 60.3 should be subjected to flattening tests. The length of the flattened specimen should not be less than 64mm. The welds of the two specimens should be located at 90° and 0° respectively in the direction of force application. During the test, the distance between the two plates is 2/3 of the outer diameter of the steel pipe, and cracks or fissures are not allowed at the weld.

(II) The impact of flattening of test equipment

During the compression test stage of steel pipes, different tests require equipment to analyze and process each link. In the current production market, the flattening welding technology and methods used are mainly based on the method of flattening at both ends. During the test, the steel pipes are processed and tested by testing machines and pressure compression, and different extrusion degrees and different extrusion locations are used to analyze the quality of the test. In the process of compressive testing of steel pipes, the best test method is to use the compression test method of German or Japanese manufacturers, so that the real test process can be realized in the production process of steel pipe manufacturing; the results are accurate; this test method can not only make the test method of steel pipes simpler, but also ensure a certain test efficiency.

(C) Influence of compression test personnel operation

During the steel pipe test operation stage, improper operation of personnel will also have a certain impact on the quality of the steel pipe flattening test. Specifically, the operation of the flattening test mainly depends on the experience and technology of the operator. For those with rich technical experience, they can strictly follow the corresponding regulations and standards to ensure the compliance of the test data with the standards. At the same time, during the inspection process, it is inevitable to encounter large and small errors. The biggest cause of this error is caused by improper operation sequence; therefore, if we want to ensure that the welding inspection stage can proceed smoothly, the relevant operators should strictly follow the procedures.

2. Discussion on the specific reasons for the flattening cracking test of welded steel pipes

(I) Material differences of welded steel pipes

The main basis for the division of steel is mainly inferred and detected by the relevant forging temperature. The division of steel can be divided into three parts, namely α iron, β iron and γ iron. Through relevant analysis, it can be seen that among these three types of iron, the cracking degree of α iron is the largest; the cracked section of α iron will form certain longitudinal cracks after relevant technical treatment, and although the other two types of iron also have relevant cracking phenomena, the overall lateral distribution is more obvious, and no large longitudinal cracks appear. In short, for the cracking degree of steel, the smaller the overall degree, the greater the value can be reflected.

(B) Impurities in welded steel pipes

In the process of testing steel pipes, in order to ensure that the overall steel pipe needs to be good and prevent cracking, it is necessary to explore the material elements to ensure the quality of the steel pipe. Cross-section layer; For sulfides in the section layer, relevant technical personnel must not only ensure the most basic content distribution, but also conduct a comprehensive analysis of impurities in the steel pipe to ensure the needs of relevant materials and avoid cracking of the steel pipe during the production process.

3. Solution strategy
(I) Improve the control of steel pipe production process

In order to ensure the quality of physical flattening of steel pipes and thus improve the overall performance of steel pipes, it is necessary to control the production process of steel pipes and minimize the probability of cracking during the production process. Improve the physical and chemical properties of steel pipes from the source, reduce the cracking rate of welded steel pipes in flattening tests, and ensure the most basic flattening test rate during the production process. By configuring different material components to construct various indicators, and provide scientific and effective test standards.

(II) Strengthen the pretreatment of impurities in steel pipes

How to treat impurities in steel pipes and strengthen its relevant specifications and requirements; the first thing to do is to improve the basic operating standards through certain chemical treatments. For ore dressing, in the process of ore dressing, you can first analyze the overall composition and understand the specific operating specifications to remove sulfides and oxides. Then, in the process of ironmaking, you must ensure the relevant monitoring efforts to ensure that impurities in steel processing are removed to the maximum extent. In the steel forming stage, you can make full use of the characteristics of related compounds to selectively remove harmful components.

4. Conclusion
As far as the current steel pipe market is concerned, the demand in the relevant market is still relatively large. For the specific analysis of steel pipe welding, we can study the relevant cracking causes very well, so as to lay a stable foundation for the reasonable improvement of my country's steel pipes. Through the reasonable analysis of the relevant causes and factors, the relevant performance can be improved in a targeted manner, thereby ensuring the improvement of the steel pipe welding manufacturing level.

To learn more, please visit the website:

https://www.baowi-steel.com/newsdetail/welded-steel-pipes.html

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BAOWI STEEL MANUFACTURING CO.,LTD

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BAOWI STEEL MANUFACTURING CO.,LTD
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