NACE MR0103 weld procedures for Duplex SS

[Bangrod]

MR0103-2007, Section 2.8.2(f) for weld procedures for Duplex stainless steels states "The WPS shall not allow welding of components with wall thicknesses that deviate by more than 20% from that of the PQR specimen.

This seems quite restrictive compared to normal ASME allowance of 2X the wall thickness of the PQR specimen. Does anyone know if this is correct, or if it is really supposed to be 200% (same as ASME) ?

Thanks,
bangrod

 

[SJones]

It is correct and is accounting for the various microstructural developments that can occur between thick and thin welds. You will also note the other restrictions in items a) to e) of the same subclause. The NACE document is, within reasonable tolerances, keeping it to "you weld it as you qualified it" since ASME IX is not concerned with phase balance and corrosion issues.

Steve Jones
Materials & Corrosion Engineer

http://www.linkedin.com/pub/8/83b/b04