I have a test report for ASTM A516 Grade 60 plate that meets all the requirements of Grade 65, what would be required to upgrade this material to grade 65.
The only way I know that would cover you is the manufacturer issue a another MTR for your plate certifying that the plate meets the requirements for grade 65. Even this gets a little fuzzy at times if the plate wasn't capable of originally of being dual certified in one standard. Carbon steel plate is not normally dual certified even though it would be possible, based on the physicals, to one standard whereas SS is. Get with you jurisdictional authority and see if they will accept a recertification.
You have to be careful as this plate maybe on high side of values used in certifying this heat of material while the average of the values is lower. A material has to meet all values for a particular standard.
You maybe lucky in that someone ordered grade 60 and the mill had this plate capable of being certified as grade 65 but certified it as grade 60 to cover the order. This is being done quite often as material is increasingly hard to procedure. This is possible as tensile values are minimums unless otherwise specified.
Again I have to emphasize get everyone involved to concur if this is done. Make sure you have the papers to cover you.
Heed unclesyd's words. Proceed only if all parties, particularly the owner, are in agreement. ASME VIII and API-650 view the toughness of Grade 65 as somewhat lower than Grade 60. If material toughness is a criteria of the code you are using, you may need to look at this a bit closer.
