The production process of seamless steel pipes is relatively cumbersome and rigorous. After the seamless steel pipe is produced, certain tests must be carried out. Do you know the flattening test method and steps of the seamless steel pipe?
1) Flatten the sample:
1. The sample is cut from any part of the seamless steel pipe that has passed the visual inspection, and the sample should be the full-face pipe section of the pipe product.
2. The length of the sample should not be less than 10mm, but not more than 100mm. The edges of the specimen may be rounded or chamfered by filing or other methods. Note: If the test results meet the test requirements, the edges of the sample may not be rounded or chamfered.
3. If it is to be carried out on the end of a full-length tube. During the test, the incision shall be made perpendicular to the longitudinal axis of the pipe at the length of the sample from the end face of the pipe, and the cutting depth shall be at least 80% of the outer diameter.
2) Test equipment:
The test can be carried out on a universal testing machine or a pressure testing machine. The testing machine shall be equipped with two upper and lower parallel platens, and the width of the parallel platens shall exceed the width of the flattened sample, that is, at least 1.6D. The length of the pressing plate is not less than the length of the sample. The testing machine has the ability to flatten the sample to a specified pressure value. The platen should have sufficient stiffness and be able to control the speed range required for the test.
3) Test conditions and operating procedures:
1. The test should generally be carried out in the room temperature range of 10°C ~ 35°C. For tests requiring controlled conditions, the test temperature shall be 23°C ± 5°C. The flattening speed of the sample can be
20-50mm/min. When there is a dispute, the moving speed of the platen should not exceed 25mm/min.
2. According to the relevant standards, or the agreement between the two parties, the distance H of the platen should be determined.
3. Place the sample between two parallel platens. The welds of welded pipes should be placed in the positions specified in the relevant products and standards. Use a press or a testing machine to apply a force in the radial direction, and at a speed of not more than 50mm/min, evenly press to the flattening distance H, remove the load, remove the sample, and visually observe the bending part of the sample.
Precautions:
During the flattening test, the flattening distance H shall be measured under load. In the case of closed flattening, the width of the contact between the inner surfaces of the sample should be at least 1/2 of the inner width b of the standard sample after flattening.
The flattening performance test of seamless steel pipe plays an important role in the hardness, melting point, corrosion resistance and pressure of seamless steel pipe, and this test should be done well.