What experiment should be done during the production of seamless steel pipes?

The production process of seamless carbon steel pipe products is relatively cumbersome and the craftsmanship is rigorous. Routine tests must be carried out after production. So how are seamless steel pipes tested? What are the methods and steps?

1. Flat test sample:

① The sample should be taken from any part of the seamless pipe that has passed the visual inspection. The sample should be the full-load surface pipe section of the pipe.

② The length of the sample should not be less than 10 mm, and it should not exceed 100 mm. The edge of the sample is allowed to be rounded or chamfered with a file or other methods. Note: If the test result meets the test requirements, the edge of the sample may not be rounded or chamfered.

③ If you want to do it at the end of the full-length tube. During the test, the incision should be perpendicular to the longitudinal axis of the pipe at the length of the sample, and the incision depth should be at least 80% of the outer diameter.

2. Test equipment:

The test can be carried out on a testing machine that meets the requirements or a testing machine of the same model. The testing machine should be equipped with two parallel plates, the width of which should exceed the width of the flattened sample, that is, at least 1.6d. The length of the pressure plate used in the test shall not be less than the length of the sample. The testing machine has the function of flattening the sample to the specified pressure.

3. Test conditions and operating procedures:

① During the test, the room temperature of the test site should generally be kept at 10℃～35℃. For steel pipe samples with relatively high test requirements, the test temperature should be constant at 23°C ± 5°C. The sample flattening speed can be 20-50mm/min. If there is any objection, the moving speed of the pressing plate shall not exceed 25mm/min.

②The pressing distance h should be determined according to relevant standards or agreement between the two parties

H——The distance between the two pressure plates under force, in millimeters——The nominal wall thickness of the steel pipe, in millimeters; B——The inner width of the flattened sample, in MM; D——The nominal outer diameter of the steel pipe, in units It is MM; A——constant, the general values stipulated by relevant standards are 0.07, 0.08, 0.09 respectively.

③Place the sample between two parallel plates. The welded joints of welded pipes should be placed in the positions specified by the relevant products and standards. When using a pressure tester to test the product under pressure in the same direction, it must be slowly pressed to the set pressure measurement layer at a pressure not greater than 50mm/min. Observe the bent part of the sample.

4.matters needing attention:

During the flattening test, the flattening distance h should be measured under the load. When closing and 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 has an important influence on the hardness, melting point, corrosion resistance and pressure of seamless steel pipe.