What are the test methods and procedures for flattening seamless steel pipes?

The process of making 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 method and procedure of the flattening test of seamless steel pipe?

flatten the sample

1. The sample is cut from any part of the seamless steel pipe that has passed the visual inspection. The sample should be the full-loaded pipe section of the pipe product.

2. The length of the sample should not be less than 10mm, but not more than 100mm. The edge of the sample is allowed to be rounded or chamfered with a file or other methods. If the test result meets the test requirements, the edges of the sample may not be rounded or chamfered.
3. If you want to do it at the end of a full-length tube.

During the test, the cut is perpendicular to the longitudinal axis of the tube at the length of the sample from the end of the tube, and the cutting depth is at least 80% of the outer diameter.

Test equipment

The test can be carried out on a testing machine or a pressure testing machine. The testing machine should be equipped with two parallel pressure plates, the width of the parallel pressure plates should 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 the specified pressure

The ability of board distance. The pressure plate should have sufficient rigidity. And can control the speed range required by the test.

Test conditions and operating procedures

1. The test should generally be carried out in the room temperature range of 10℃35℃. For tests that require controlled conditions, the test temperature should be 23℃±5℃. The flattening speed of the sample can be 20-50mm/min. In case of dispute, the moving speed of the pressing plate should not exceed 25mm/min.

2.the platen distance H must be determined according to relevant standards or agreement between the two parties

H—The distance between the two pressure plates under force, unit mm

Place the sample between two parallel pressure plates. The welded joint of the welded pipe should be placed in the position specified by the relevant product standard. Use a press or a testing machine to apply a force in the radial direction, uniformly at a speed of not more than 50mm/min After the ground is pressed to the flattening distance H, remove the load, remove the sample, and observe the bending part of the sample with the naked eye.

Note:1) During the flattening test, the flattening distance H should be measured under load. For closed flattening, the contact width of the inner surface 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.

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