SA258-C Vs. SA-516-70

[FarisJ]

I have a sulfuric acid pressure vessel that I need to replace its cup due to a blister in it. The original material of the vessel is SA-258-C. The manufacturer has SA-516 grade 70 material available in hand. Would it be ok to use SA-516-70 for the vessel cup and is there any considerations that I need to take into account, say welding for instance?

Thanks,

 

[david339933]

I believe you mean SA-285-C? In the past SA-285-C was vastly used for pressure vessels/boilers, but for the most part has been replaced by SA-516-70 material. WPS good for SA-285-C is good for SA-516-70.

 

[weldstan]

Concur with david. SA-516-70 has greater strength and is fine grain melted while SA-285 C is not. Your SA-285C may or may not have been fully killed.

 

[FarisJ]

Thank you David and Weldstan,

Yes I mean SA-285-C, sorry for the typo. What I understand from your response is that it is ok to weld the SA-516-70 cup to SA-285-C body of the vessel. I know that SA-285-C has a lower yield stress than SA-516-70, so which welding consumable should I consider, E7018?

 

[david339933]

Yes.

 

[IFRs]

Before you use 516-70 evaluate brittle fracture issues based on thickness and lowest temperature.

 

[weldstan]

IFRs,
SA-285 C has considerably less toughness at low temps than SA-516 70. SA-285 C for the most part could not meet impact toughness requirements per ASME VIII at 32 F.

 

[IFRs]

Weldstan -
I fully agree that 516-70 is superior to 285-C in low temperature toughness but that would not stop me from making sure it was suitable for the service. I am a bit conservative...