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Recrushed Slag Question

Recrushed Slag Question

Recrushed Slag Question

I'm looking for clarification on a point that Section IX does not seem directly address.
Q: If a PQR is made using recrushed slag, is it permitted on the supported WPS to use new flux OR recrushed slag (of the same original flux)?

Assume for the purpose of argument that the recrushed slag has been certified in accordance with Section II, Part C, as required by the applicable Code paragraph (2010 Ed); reproduced below:

QW-404.36 When flux from recrushed slag is used, each batch or blend, as defined in SFA-5.01, shall be tested in accordance with Section II, Part C by either the manufacturer or user, or qualified as an unclassified flux in accordance with QW-404.9.

p.s., just to be clear, I have never used recrushed slag and would never endorse its use by others!

"Everyone is entitled to their own opinions, but they are not entitled to their own facts."

RE: Recrushed Slag Question

Functionally, you would need to verify (by testing samples of weld using the re-crushed slag) that the "process" is correct. It isn't that any PQR or WPS is "perfect" or is bureaucratically "impeccably written" by a lawyer, it is that the weld produced by a competent welder using that WPS is able to make quality welds under the same circumstances as the WPS was certified.

So, the threat by using recycled slag is that left-over bits of rust, corrosion, metal, grinding debris or melted slag or removal debris or contamination while recovering the slag is melted into the SAW puddle and forming inclusions and flaws.

And that, you have to verify.

RE: Recrushed Slag Question

The question is whether or not recrushed slag qualifies the use of virgin flux.

The common sense side of me says yes, because if you can get the recrushed slag to pass the tests listed in SFA-5.01 (as assumed by the OP), the virgin flux obviously will. And the virgin flux has passed those tests by virtue of the requirements to gain the classification.

The technical side of my says no, because QW-404.36 is a yes or no essential variable; either it's used or it's not - there is no special character (+, -, >, <, etc) that precedes recrushed slag in Table QW-254. In other words, if you qualify with recrushed slag, you're only qualified to use recrushed slag. It does not give you a free pass to use virgin flux, even if the recrushed slag you used in the qualification test was of the same type of flux. If you don't use recrushed slag, you have to use something else...and are you qualified to use that something else?

Personally, if I knew this was going to be the situation, I would qualify both with individual PQRs and create one WPS for use in production to avoid the ambiguity.

Ironic metallurgist, this topic would make an excellent Section IX interpretation.

The devil is in the details; she also wears prada.

RE: Recrushed Slag Question

Ironic metallurgist:
“Recrushed Slag?” How many times has the slag been crushed already, where did it come from, what is its make-up? This seems like an expensive means of gaining a little volume of something of dubious quality and purpose. This is a weld puddle cover and scavenger in many welding processes and contains many impurities which you don’t want in the weld, and then you are going to reuse this material, and reintroduce those impurities. I have certainly seen and heard of collecting the granular flux used in the SAW process, cleaning it of small particulate matter, drying it, etc., and reusing that along with some percentage of new flux. New flux contains many elements, such as scavengers, alloying elements, etc. which are consumed when the flux is melted in the welding process. So, these elements will no longer exist in the crushed slag, but a bunch of junk will be reintroduced. Slag works good for GeoTech fill and you don’t have to crush it.

RE: Recrushed Slag Question

My question is not about the quality of recrushed slag (I am as dubious as you are).
My question is whether for practical purposes it becomes an essential variable; i.e., if you qualify with recrushed you may not use new flux and vice versa.
I've since found that SFA5.17, Annex A6.1.5 comments on it. My thinking is that the Code implies but does not declare the change to be not permissible. My engineering judgment says it should not be permitted (but then my engineering judgment also tells me never to get near these kinds of schemes).
Good suggestion DVWE, an interpretation would help clear this up.

"Everyone is entitled to their own opinions, but they are not entitled to their own facts."

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