Below Spec flanges - A350 LF2

[piperUK]

Hi,

I would appreciate the advise of any pipng materials experts.

For a forthcoming project we have purchase some A350 LF2 flanges that have failed impact and tensile testing. Low max tensile, low elongation, low charpy impact testing values (at -50DegC).
The supplier is asking for a concession but I don't think it correct to grant one based on the test data presented.
I would like to know if re-heat treating the items would improve the values for all three areas of failure.


Many Thanks.

 

[redpicker]

I wouldn't recommend approving the concession. I don't even care what the application in, if it was ordered to A350 LSF and does not meet the requirements, I would not approve the material.

Whether or not re-heat treatment would improve the properties, there isn't enough information given. Regardless, the only way to know for sure is to re-heat treat and re-test.

rp

 

[metengr]

piperUK;
There is not enough information to provide specific guidance regarding success of reheat treatment. There should be no concession - if the material is nonconforming you must reject it for use or disposition it.

Disposition of the nonconformance is another matter. If the chemistry of the flange material is out of conformance with SA 350, this cannot be corrected. If the original heat treatment of the flange was incorrect, but the chemical analysis is acceptable, reheat treatment may be an option.

The risks associated with reheat treatment is distortion and verification of acceptable mechanical properties. How are you going to prove reheat treatment is the correct disposition without further mechanical testing? Do you have enough material from this heat of steel to verify reheat treatment is acceptable?

 

[piperUK]

Gents,

Thank you very much for your replies.

My initial thoughts were that the concession should not be granted.

The non-conformities are:

Max tensile = 478 Mpa (Specification 485-655)
% Reduction = 26 (Specification 30% min)
% Elongation = 12 (specification 22 Min)
Impact test (Charpy 300J) 22, 31, & 31 (specification 35J min ave, 28J min ind.

Note there are some local codes that exceed the ASTM A350 LF2 requirements.

The chemical composition was to spec A350 LF2 and acceptable.
The items are DN50 1500RF Blinds - distortion through reheat should be OK.

My view is that the supplier should apply heat treatment and then retest (there should be sufficient material for more test pieces).
If testing fails again then a new batch of flanges should be sourced. Problem is these are shutdown critical items and not much time available.

Any thoughts?

 

[metengr]

Yes, I would agree with this disposition test plan.

 

[stanweld]

Scrap the lot! Any company that would have the gall to call the above out of spec material A-350 LF2 cannot be trusted.

 

[metengr]

stanweld;
Given the above time constraints, sometimes even a blind pig can find an acorn.

 

[stanweld]

If reheat treatment must be done to meet schedule, and having to do so myself in the past, I recommend that the lot be reheat treated. Select one forging at random or the heaviest to be cut and mechanically tested. Purchaser should witness testing.

I have experienced cases where reheat treatment did not provide the required properties and further time was lost.

 

[redpicker]

I agree with stanweld. My experience with LF2 requirements are they are typically met with a normalizing treatment, which is hard to mess-up. The low % elongation and low CVN absorbed energy would have me concerned. I would expect that the supplier probably already tried re-heat treatment before asking for a concession. I'd be curious as to what went so wrong that the required properties weren't met.

rp

 

[metengr]

I would suspect the problem with this plate could be grain size, given all other factors are acceptable. I have seen this before.

 

[piperUK]

Gents,

Once again thanks for all the replies.
I have replied to the Vendor that a concession will not be granted and that it is his choice if he wishes to re-heat/re-test or source new material.