Vessel Design for -95¦C Temperature 1

[magicking]

If I would like to avoid impact test of the vessel with MDMT = -95°C by using SA-516 Gr 70 material. What is the minimum wall thickness of the vessel to order to meet ASME code? The design pressure is only 50 kPa. Thanks for your help.

 

[SnTMan]

I'm not gonna do it....

 

[metengr]

If I would like to avoid impact test of the vessel with MDMT = -95°C by using SA-516 Gr 70 material.

Why????? I would suggest you review ASME B&PV Code, Section VIII, Div 1.

 

[StoneCold]

You might want to look at the cost difference between impact testing and switching to a stainless material that you can get an exemption on. Even though you are at a very low pressure that cold material can be dangerous and probably warrants testing or an alloy change.

Regards
StoneCold

 

[stanweld]

SA-516-70 is incapable of meeting Code mandated impact testing at -95 C. You should use 3 1/2% Ni alloy steel.

Thickness is based on pressure and diameter (and temperature); you've only provided pressure.

 

[magicking]

Thanks stanweld,

The diameter is 20"ID. I've read ASME B&PV Code Section 8 Div 2, it indicates that I can reduce the MDMT to -104°C, as long as the stress ratio is below 0.24 (3.11.2.5). There are 3 equations to calculate stress ratio, which one I should use?

 

[Guest102023]

At the risk of being blunt, I think you need to pay a welding engineer who knows his way around the Code for a couple of hours of consulting. This forum can be very helpful, but it is not the ideal way to design a PV.

 

[MachyDude]

CS at -95°C..!!! Not a good idea i guess. can u tell me where u gonna use it??

 

[MachyDude]

i dont think Sa-516 is suitable -95°C temp. better use stainless....

 

[stanweld]

magicking,
You must qualify your welding procedures with impact testing at -95 C in weld metal and the HAZ of the SA-516-70 material. While you can select a weld filler metal that will meet the impact test requirements at -95 C, the HAZ is incapable of meeting the Code mandated absorbed energy requirements.