Flattening test ASME SA 530 2

[bagnamento]

According to ASME SA 530 (sect. 19), flattening test shall be performed in two steps: the first step, which is a step for ductility and a second step, which is a test for soundness.
The first step consists in flattening a section of pipe between two parallel plates until a given distance, during the second step flattening is continued until the specimen breaks or teh opposite walls of pipe meet.

The specifications gives the conditions for acceptability of the first step (no cracks or breaks,...)

Which are the conditions for acceptability of the second step?
Is the test unacceptable if the specimen breaks or is it unacceptable only if it breaks because of laminations or other defects (see sect 19.3)?

 

[Carburize]

During the second phase of the test the material would be rejected if major material laminations or weld defects in the case of seam welded pipe were revealed.
Cracking from surface discontinuities or due to very high strain at the 3 o'clock and 9 o'clock positions are not cause for rejection.

 

[metengr]

Per my review of SA 530, for the second step you are evaluating is soundness, not ductility. The ductility is evaluated in step 1, when the value of H is reached by equation (2) of 19.1.

After the value of H is reached in step 1 you continue with the flattening until fracture OR the ends of the sample meet. If tears or cracks occur you need to review 19.3.4, which provides an exemption for pipe that has a low diameter to thickness ratio that could induce tears during flattening.

If the specimen passes step 1 and fails in step 2 before the ends meet, the failure or break should be visually inspected. If the break is not caused by any of the conditions listed in 19.3 (1-3), or you have the condition mentioned in 4 (the low diameter to thickness ratio), this is acceptable.

 

[Goahead]

Hi,
when the flattening test is used for testing seam welded pipes or tubes, the weld should be placed at 90° from the direction of applied force. The test fails if the weld breaks when or before opposite walls of the tubing meet.

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