ASTM A203, Grade B for Propane Tanks 1

[Ossareh1352]

Dear Sir/Madam,
For your kind information in our Project (BID Boland II-Iran) , we have two Propane Storage Tanks (50,000 m3,each , Temp.-50c). The material for these Tanks in our Contract is ASTM A203 Grade B , but in our normal practice we have used ASTM A 573.I will be highly appreciated , If anyone could clarify for me, any advantages of ASTM A203 Grade B(If any) and Please let me know that do you recommend this Material for the said Propane Tanks or not? Thanks in advance. Best Regards

 

[metengr]

Ossareh1352;
ASTM A 203 is a nickel alloy steel plate for welded pressure vessels. Typically used for pressure vessels in moderate to low temperature service.

ASTM A 573 is only a structural quality grade carbon steel plates for improved toughness. There is no nickel addition which is used to improve notch toughness.

If you are using ASME Section VIII, Div 1 for construction of the storage tanks, use the A 203 pressure vessel quality steel.

 

[Ossareh1352]

Thank you. For your information our Design Code is API 620 and our Propane Tank is not a pressure vessel. With this information could you let me your new recommendation?

Thanks

 

[metengr]

Ossareh1352;
Well, thanks for the clarification. In my opinion, I have serious doubt about having sufficient notch toughness at -50 deg C (-58 deg F) as your MDMT. You will need to conduct impact testing per the requirements in Table 4-1 of API 620. ASTM A 573 is carbon steel plate with increased notch toughness. You have no nickel in this steel and you are relying on a fine grain practice to achieve suitable notch toughness at lower temperature service.

My recommendation still stands that I would go with A 203 plate for this storage tank to ensure adequate notch toughness at your stated MDMT.

 

[soozi]

When designing low-temperature equipment,notch toughness ranks high in importance, because a part or structure may be failed due to a notch or other stress concentration. Test results measure the steels capacity to absorb energy, and thus signify its ability to resist failure at points of local stress concentration.in this regard utilization of improved toughness materials (e.g. A203) as requested by your contract is highly recommended.