[MW:29099] Re: Hardness for SA516 Grade 70

The hardness of SA516 Gr 70 after welding (in the WM and the HAZ) can easily get above 200BHN depending on many factors such as

1. Using a low HI

2. Using single pass welds

3. In a weld joint welded from both side, the weld hardness of single pass welded after root gauging.

4. Using a alloyed filler wire

The above case based on AW condition although a PWHT will be beneficial in the hardness reduction. It is to be noted that actual base metal hardness will be in the range of 150-170 BHN. A good hardness control in the HAZ can be achieved by increasing the nos. of pass in the weld joints by increasing the travel speed which will give the effect of the TBW (temper bead weld).

Specific to your points, the hardness limit of 200BHN comes due to the use of the vessel in the sour service where it can lead to wet H2S cracking. For us this limit is defined in our engineering specification although this topic is not covered in the Section VIII. NACE MR0175 limit hardness upto 22HRC or 238BHN.

Regards

Sandeep Kumar

On Sunday, February 10, 2019 at 1:52:08 PM UTC+3, RKD wrote:

For a pressure vessel designed with stamped under ASME VIII Div.1, there is a requirement that: "Hardness values should not exceed 200 brinell for the welds / material of shell."

Shell material is specified as SA516 Grade 70.

I am concerned the requirements for hardness and material will automatically require stress relief for all pressure vessel parts.

Would SA516 Grade 70 have hardness lower than 200 Brinell?

Thank you.

Regards,

RKD

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