Molybdenum/iron content in zirconium 1

[Millar]

I have an old heat exchanger with supposedly zirconium tubes (grade 702). When I attempted to PMI the material, the results do not match the current ASME/ASTM spec for grade 702 zirconium. Specifically, the analyzer is reporting around 1 to 1.5% Moly and an iron content exceeding 0.5%.

The specification I have does not specify any Moly and limits iron content to 0.2% maximum.

Does anyone know if grade 702 ever permitted such alloy contents? I appreciate any advice.

Millar Iverson

 

[Carburize]

Is your analyzer properly calibrated for zirconium alloys?

 

[Millar]

Good point. I followed the normal standardization procedure for the analyzer (uses a 316 stainless steel calibration block). There is no mention of a special calibration for other alloys.

 

[Carburize]

I would check with the manufacturer - typically analyzers have to be set up specifically for the alloy types being tested.

 

[stanweld]

I checked some of my old "1960s" literature as well as more recent regarding Zr and no Mo containing Zr alloys were found. Like Carburize, I suspect that the analysis is in error and you should check with the analyzer manufacturer. Your analyzer may not be able to provide a true quantitative analysis for the 702 alloy and you may have to send it to an appropraite chem/met lab for a true quantitative analysis.