How to ensure the strength and flattening test requirements of seamless pipes

Seamless pipes (SMLS) are a common metal material and are widely used in petroleum, chemical, electric power, machinery and other fields. In order to ensure the strength of seamless pipes and the accuracy of flattening tests, we need to take a series of measures.

1. Ensure the quality of raw materials for seamless pipes

The raw materials of seamless steel pipes should be made of high-quality steel billets. After heating, rolling, cooling and other process flows, the heating temperature, rolling pressure, cooling speed and other parameters are strictly controlled to ensure the strength and toughness of seamless steel pipes.

2. Perform reasonable heat treatment process
Seamless pipes need to undergo multiple heat treatment processes during the manufacturing process, including annealing, normalizing, quenching, tempering, etc. These heat treatment processes can change the internal structure of seamless pipes, thereby improving their strength and toughness. At the same time, the heat treatment temperature, time, atmosphere and other parameters must be strictly controlled to ensure the quality of heat treatment.

3. Perform accurate flattening tests
The flattening test is a commonly used strength test method. In order to test the performance and bearing capacity of seamless pipes under pressure, standard schemes such as ASTM and GB are generally used for testing. By flattening the seamless steel pipe to a certain shape and observing its rebound, its strength and toughness can be judged. When conducting the flattening test, it is necessary to select a suitable specimen, accurate test temperature and pressure to ensure the accuracy of the test results.

Requirements and precautions for seamless pipe flattening test:

Test steps:
1. Select a whole seamless pipe for testing and reinforce both ends to prevent distortion during the test.
2. Place the seamless pipe in the test machine and adjust the pressure and speed. It is recommended that the initial pressure does not exceed the yield strength of the pipe, and the pressure speed is appropriately controlled between 1-5mm/min.
3. Start applying pressure, record the pressure, displacement and other change data and mark the test information for later data statistics and analysis.
4. Gradually increase the pressure during the test until the end of the test. After the end, the pressure needs to be released to avoid damage to the test device.

Test conditions:
1. The test environment temperature should be between 15℃ and 35℃.
2. No intervention operation shall be performed during the test unless it is to prevent accidents in the test machine or equipment.
3. All test samples must meet the specified standards and requirements.
4. Before the test, the test equipment should be debugged, such as adjusting the pressure gauge and displacement gauge to ensure the accuracy and reliability of the data.
5. The test material should be uniform. If the material has defects such as flaws and cracks, it will cause distortion of the test data.

Notes:
1. The pipe needs to be reinforced during the test to avoid affecting the results due to twisting and deformation.
2. The safety of the equipment must be ensured before the test to avoid any unexpected situations.
3. The speed of pressure change needs to be controlled during the test to avoid additional pressure and damage to the pipe.
4. After the test, the data needs to be processed and analyzed in time to evaluate and compare the test results.
5. When conducting the flattening test, safety issues such as collapse of the test structure and loss of equipment control should be prevented.

5. Take effective protective measures
Seamless pipes are susceptible to corrosion and damage during transportation, storage and use. Therefore, we need to take effective protective measures, such as coating, packaging, storage, etc., to protect the surface quality and integrity of seamless steel pipes.

In summary, to ensure the accuracy of strength and flattening test of seamless pipes, comprehensive control and management are required from raw materials, heat treatment process, flattening test and protective measures. Only in this way can the quality and performance of seamless steel pipes be guaranteed to meet the needs of different fields.

Read more: Non-destructive testing of seamless pipes or Analysis of seamless steel pipe costs