Super Duplex (25Cr) Girth welds Charpy Test Temperature

[Mrinet]

Hello,

Is Super duplex (S32760) girth welds be tested at -71 degrees C. The base material was tested at -71 degrees C (as per DNV OS F101) where the MDT is -51 degrees C. This is a line pipe.

I know with Solution annealing (base material) can be successfully tested at -71 degrees C. Can this be achievable for welds, which will not be solution annealed. Any thoughts?

 

[Guest102023]

My immediate reaction was a negative one, but my curiosity was piqued and so I searched my archive.

The following info from the manufacturer claims good low-temperature as-welded toughness for the Zeron alloy, using the GTAW process only:

http://www.rolledalloys.com/trcdocs/corrosion/Zeron100_A4_DS_Bul.pdf

It might be a good idea to contact Rolled Alloys for their best welding recommendations. Good luck - hope your pipe is not too massive!

 

[metengr]

Mrinet;
What is the piping code of consruction? You should follow these requirements for impact testing of welds, in addition to base materials.

 

[Mrinet]

brimstoner, metengr,

Thanks for your response.

Pipe is 30km...it is long (looking at 12m lengths) hence GTAW is not an option.

The code of construction for Materials and Welding is DNV OS F101, which calls for Impact test at T-20 degrees C. (T is min. design temp). Design temp is -51 degrees C.

As said before....for base materials, -71C is achievable as it will be solution annealed. But the girth welds are not! Any thoughts on success stories of welds passing such low temperature?

ISO only calls for welds be tested at min, design temperature. Is -71C a bit overkill as per DNV? Any thoughts.

 

[metengr]

Mrinet;
There is no need to guess. Run a weld coupon that simulates field the field weld and run impacts. This is easy enough to do and will answer your question.