Impact test Temperature for A 333 Gr.6 material 3

[ligin18]

Hi All
The design temperature is for our project is -68 degree C.The material selected is ASTM A333 Gr.6.As per my understanding impact test temperature for ASTM A 333 gr.6 is -45 degree C.Please clarify whether impact test can be done at -70 degree Celsius for ASTM A 333 Gr.6 material.

 

[metengr]

The minimum impact test temperature for Grade 6 by material specification is -45 deg C. Yes, you will need to impact test at temperatures below -45 deg C for use. Can this material make -70 deg C? Maybe - it depends on thickness and prior thermal processing.

You really need more nickel to ensure adequate toughness at -70 deg C, in this case Grade 7 will meet the notch toughness requirement at -75 deg C with no sweat.

 

[weldstan]

While I have seen 333 gr6 meet absorbed energy requirements at -65 C, I have not seen it at -70 C. You will need to discuss with manufacturers. Why not choose grade 7?

 

[pradipgoswami]

C-Mn LT steels such SA 333 Gr6 would NEVER be the safe material meeting consistent impact requirements @-70 Deg C.
As stated by MetEngr, 2.5% Nickel Steel(SA 333 Gr7) is the minimum option at this LT range of -70 to -75 Deg C. SA 333 Gr6 is more amenable for design considerations @-45 Deg C , maximum upto -50 Deg C.
Same applies for welding consumables also.2.5% Nickel welding consumables E-8016/8018C1(SMAW)and equivalent SAW, GTAW products have to be used for meeting the safe impact requirements.
I had handled welding and fabrication of vessels, exchangers, Piping for Ethylene, Polyethylene, and Propelyne services involing -75 Deg C down to -100DegC , involving 2.5% & 3.5% Nickel steels. Meeting impact properties at such subzero temperature are extremely challenging, when demanding clients' requirements are involved.
Thanks

Pradip Goswami,P.Eng.IWE
Welding & Metallurgical Specialist
ca.linkedin.com/pub/pradip-goswami/5/985/299