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Up Topic Welding Industry / Metallurgy / SA516 Gr 65 vs Gr 70
- - By Boon (**) Date 08-10-2008 09:28
In one of our project, the specification calls for SA516 Gr. 65 materials. We propose to use SA516 Gr. 70 materials as they are in stock.
Can anyone advise what is the main difference between the two specifications and is there any restriction in selecting one over the other.

Regards
Boon
Parent - - By G.S.Crisi (****) Date 08-11-2008 21:25
There's nothing wrong in using Gr 70 instead of Gr 65, for the simple reason that Gr 70 is a better material than Gr 65. Your client should be happy at the change that won't cost him any additional money.
Giovanni S. Crisi
Sao Paulo - Brazil  
Parent - - By Boon (**) Date 08-12-2008 04:07
What is the comparison for better material? Is it material strength, corrosion resistance or others?

Boon
Parent - - By ravi theCobra (**) Date 08-12-2008 15:59
What  is  the  application  ?
Parent - - By Boon (**) Date 08-12-2008 16:08
Flue gas at about 350 degrees C.

Boon
Parent - By ravi theCobra (**) Date 08-12-2008 19:28
anything   else   corrosive  or  sour  service   ?
Parent - - By G.S.Crisi (****) Date 08-12-2008 22:48
Minimum tensile strength of A 515 Gr. 65 is 65 ksi. Minimum tensile strength of A 515 Gr. 70 is 70 ksi.
Corrosion resistance is the same. None of them are suitable for corrosion service.
Be careful, 350 ºC is about the maximum temperature at which carbon steels can be used.
Giovanni S. Crisi
Parent - - By js55 (*****) Date 08-14-2008 19:03
With many manufacturers the 65 and 70 are the exact same stuff. Its economically efficient. They are poured from the same heats, run through the same heat treat, and tested with the same testing procedures. If the resulting mechanicals overlap both specs they will be dual certed.
In fact triple cert materials 60/65/70 are not that uncommon.
Parent - By jon20013 (*****) Date 08-15-2008 08:17
Dual or multi-cert materials are also wonderful when running PQR's! ;)  Get to take credit for both Group numbers, lol!
Parent - - By Quibo (*) Date 08-18-2008 21:46
Hi G.S.Crisi, What is the reason why the 350ºC is the maximun temperature in which carbon steels can be used?

Thanks a lot for your answer.
Parent - By G.S.Crisi (****) Date 08-18-2008 23:47
Because at about 370 ºC of continuous and long time service two phenomena start taking place in carbon steel: creep and graphitization.
Continuous service means 24 hours a day, not merely 8 hours. Long time means 6 months or more, not two weeks.
Giovanni S. Crisi 
Up Topic Welding Industry / Metallurgy / SA516 Gr 65 vs Gr 70

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