crack on a105 flanges
crack on a105 flanges
(OP)
dear friends,
during hydrotest of 6"#600 pipes we found some cracks in the taper area of flanges, the cracks are far from weld seams, what is the main reason of these cracks, welding procedure or material construction (forging of flanges)? what kind of test is necessary to find out the reason?
Thank you. H�
during hydrotest of 6"#600 pipes we found some cracks in the taper area of flanges, the cracks are far from weld seams, what is the main reason of these cracks, welding procedure or material construction (forging of flanges)? what kind of test is necessary to find out the reason?
Thank you. H�

RE: crack on a105 flanges
If as you posted that they are visible then a quick test would be dye penetrate. The second option would be magnetic particle.
To help with your problem answers to the following questions would be nice.
What is the orientation of the cracks?
Are they visible before or after the hydro?
What is the country of origin for the flanges?
What was the test pressure and temperature?
RE: crack on a105 flanges
The taper was radiographed and found to be full of defects from welding. Instead of receiving a single piece forged flange we received a fabricated piece that was in fact a counterfit, and a very bad one at that.
Do a radiograph and see what is inside, you may be surprised.
Our product originally came from China.
RE: crack on a105 flanges
RE: crack on a105 flanges
As A105 is carbon steel MPI will reveal all surface-breaking cracks. Hardness and PMI (Positive Material Identification) in the vicinity of and distant from the cracks (for comparison) may give some indication of localised metallurgical anomalies.
Radiography should be a last resort for volumetric NDT considering both the hazards involved (radiation, chemicals) and its poor capability for randomly-oriented crack detection .
To perform volumetric NDT use encoded recordable UT (Phased Array and/or TOFD). It has superior detection capabilities than RT for randomly oriented cracks and planar flaws and a small quantity of water is the only consumable. A combination of TOFD and Phased Array will detect both embedded and surface flaws.
RE: crack on a105 flanges
RE: crack on a105 flanges
RE: crack on a105 flanges
Do ASTM forged flange specs allow for weld repairs?
RE: crack on a105 flanges
RE: crack on a105 flanges
Not every 'linear indication' is a crack. If remote from the weld it could be a forming defect such as a fold or lap.
In my past experience the 'root cause' of defects in fittings was often the name of the (3rd-world) country of origin. Despite the fact they all had ASME stamps.
RE: crack on a105 flanges
You may be able to remove minor surface flaws with light grinding in areas with sufficient meat. You would rather not weld (with possibly mandatory PWHT), but that decision depends on the size of the fitting and the cost implications.
RE: crack on a105 flanges
i performed tensile, hardness, impact, and chemical composition tests in a new flange with the same heat number, the results are enclosed.
as you see, the carbon equivalent is about 0.49.
in your opinion what is the main reason for the cracks.
it is very interesting that after ut test we saw some flaws in two area of the flanges(0 and 180 degree on the holes area).
Thank you. &