Hardness Test Criteria after PWHT (A335 P11) 1

[newbeehere]

Good day to all!
Please help me regarding Hardness Test after PWHT.
Our company has already done PWHT for material A335 P11 using the temperature of 730 DEGREES CELSIUS.
As per ASME code B31.1 the temperature for this material is 650 to 700 Degrees Celsius only.
So, we exceed the required temperature.

Our client ask us to do a hardness test on HAZ on all 100 joints.

My questions are:
1. What is the Hardness criteria of A335 P11 after PWHT?
2. What code, or what reference should I use?
3. Aside from doing hardness test and cut-out of joint (re-pwht); is there any way/ procedure that I may use to present to my Client?

Thank you so much for your help.


-ALEX

 

[metengr]

The maximum hardness after PWHT for P-No 4 material per B31.3 Table 331.1.1 is 225 BHN. Regarding your PWHT temperature, you are within the range permitted for P-No 4 base material - 704 to 746 deg C at least for B31.3. B31.1 tends to be a bit more conservative with their stated PWHT temperature ranges. I would present your hardness data and see if the client agrees with your approach if below 225 BHN.

 

[newbeehere]

@metengr

Thank you so much for your response.

You are right that B31.3 has 225 BHN. yet, our team is still in doubt because our project is Power Plant and the code we used is B31.1.

B31.1 did not mention any hardness test criteria.

Is it advisable to refer B31.3 as our Hardness reference in lieu to our reference code B31.1?

Thank you so much sir,

regards
-alex

 

[metengr]

Yes, I have used a reference code like B31.3 to defend hardness results. Understand, each committee has a different take regarding PWHT temperature range based on experience. The bottom line is this, if you have not exceeded the lower critical transformation temperature, tempering has been achieved. The concern is maximum hardness not minimum hardness for Cr-Mo steels. Exceeding the upper PWHT is more of an administrative issue, which is why I like Section I and other construction codes which do not place an upper limit on PWHT unless the lower critical transformation temperature has been exceeded. In this case, you will know based on elevated hardness values.

 

[weldstan]

While B31.1 does not address hardness of welds in P11 material, hardness after PWHT as mandated in B31.3 is readily achievable.

If your client did not specify a min/max hardness, he is doing it for information. Any re-heat treatment that the client might require would be at his cost.