Weld Clad Hard Facing Qualification and Chemistry.. 1

[acrmnsm]

I'm trying to understand the ASME Chemistry requirements under section IX.
A weld clad can have the chemistry taken from various locations, I cant seem to find which locations are required.
Also closer to the fusion line the chemistry of the clad material will not be anythign liek the clad material but an alloy of the clad plus the parent/base metal. How does ASME take account fo this? Do I need to be worried about it?

 

[metengr]

The information for a corrosion resistant weld overlay (CRO) qualification is in Section IX, QW-462.5 (a).
Please see Notes 1-3. All of the information is there.

 

[acrmnsm]

Thank you so much for your considered reply. I am indeed familiar with QW-462.5(a) which is essentially what my question is about.

So my interpretation is that I can take the chemical analysis specimins from wherever I like, but the thickness at that location defines the min thickness qualified? There does not seem to be a sepcific requirement for which of the locations must be used, implying that you can choose where to tkae it from to saitisfy your own clad thickness requirement?

So I think it would be a bad idea to try and hard face a material for a desired thickness of say 2mm, with a 5mm thick clad, which is then machined down to 2mm, or for qualification has had samples taken from 2mm . I think the local chemistry at 2mm will be pretty poor due to the amount of heat to lay down 5mm thickness. I would prefer to take chemistry from weld that was closer to the reuired clad thickness, it seems more likley that the chemistry is more likley to be undilted.
Am I wrong?

 

[acrmnsm]

Apologies for the typos. Terrible.

 

[metengr]

acrmnsm;
I inadvertently was thinking of a CRO in lieu of hardfacing - my apologies. Review Section IX, QW-453 first, see Note 9 below, then go to QW-462.5. Per the Notes a I mentioned above, you are permitted to perform chemical analysis on the as-welded overlay surface directly or the prepared surface directly. For horizontal drilling see Note 3. It really is self explanatory.

Note 9 When a chemical composition is specified in the WPS, chemical analysis specimens shall be removed at locations specified in QW‐462.5 (b) or QW‐462.5(e). The chemical analysis shall be performed in accordance with QW‐462.5(a) and shall be within the range specified in
the WPS. This chemical analysis is not required when a chemical composition is not specified on the WPS.

 

[acrmnsm]

With regard to hardfacing vs cro. I had noted that, but did not wish to appear ungrateful in correcting you. I could derive from your response the correct information.

It really is self explanatory.

I appreciate that, it just seems too easy/simple.

We would like to invoke note 9 -ie not include a chemistry on the WPS, such that chemistry is not required in the qualification, but the client requires it.

Thanks for your help.

Any comment on the thickness of the original weld as relted to the thickness of the clad required?

 

[metengr]

acrmnsm;
The minimum thickness of the hardfacing overlay is specified only by the WPS, per Note 2. Why? Because various welding processes can result in varying dilution, so the objective is to specify a minimum qualified thickness of hardfacing overlay where in production the hardness and/or chemical analyses ensures the desired hardness and/or chemistry specified for hardfacing.

 

[acrmnsm]

Why? Because various welding processes can result in varying dilution, so the objective is to specify a minimum qualified thickness of hardfacing overlay where in production the hardness and/or chemical analyses ensures the desired hardness and/or chemistry specified for hardfacing.

Which is pretty much exactly what I thought. Excellent thanks.