PetroStreet

The hardness limit of carbon steel welds is usually kept at less than 200 HB.
At our locations, the hardness is coming out in the range of 210-220 HB. What are the main reasons and actions to be taken?
Can we go with these readings?

Are you talking about pressure vessel welds or piping?
What is the design code?

Piping. ASME B31.3

As per ASME B31.3, carbon steel weld joints are not mandatory to be checked for hardness after doing PWHT.
Is PWHT a service requirement in your case and project specifications ask for hardness check?

Yes the actual material is A-333 Gr. 6 requiring PWHT as per specifications.

arcpro,
Officially, by the book, you just have to follow the requirements laid down by the project specifications / piping owner.
Off-the-record, hardness of killed carbon steel can be acceptable to 210 HB.
Talk to your piping owner / client. He has to give the final decision on this.
Most likely you would be repeating PWHT on weld joints exceeding the value mentioned in specs.

Thanks Boss.