A flattening test is a crucial method for assessing the quality and mechanical properties of Electric Resistance Welded (ERW) steel pipes. This test helps determine the pipe’s ability to withstand deformation without cracking or failing, ensuring it meets safety and performance standards. Below are the steps to perform a flattening test on ERW steel pipes.
1. Prepare the Specimen
Cutting the Specimen: A sample section of the ERW steel pipe is cut to a specific length (usually around 50-100 mm or based on the pipe diameter and test standard).
Conditioning the Specimen: Ensure the sample is clean and free from any surface defects that could affect the test results.
2. Position the Sample
Place the pipe section horizontally between two flat plates on a universal testing machine or flattening press. Ensure that the welded seam is positioned at a 90-degree angle to the direction of the applied force.
3. Apply the Load
Begin applying pressure gradually to flatten the pipe section. The pressure should be applied uniformly and at a steady rate.
The pipe is flattened until a predetermined distance between the plates is achieved, typically equal to a certain fraction of the pipe's outer diameter (for example, one-third of the pipe's original diameter, depending on the standard being followed).
4. Observe the Deformation
As the pipe is flattened, observe for any signs of cracking, especially along the weld seam.
The weld seam area is the most critical part to evaluate since it’s more susceptible to failure during deformation.
5. Evaluate the Results
Once the flattening distance has been reached, inspect the sample visually for any cracks, tears, or fractures.
If the sample exhibits no visible defects, the pipe passes the flattening test.
If cracks or significant deformations occur, the pipe fails the test.
6. Document the Findings
Record the test results, including the flattening distance, any defects observed, and the applied load.
Compare the results with applicable standards, such as ASTM A53, A500, or other relevant specifications.
Standards for Reference
ASTM A53 and ASTM A370 are commonly followed standards that outline the procedures for performing flattening tests on steel pipes, including ERW pipes.
The flattening test ensures the ERW pipe can withstand compressive forces and maintains its integrity during practical applications.