PWHT Maximum Temperature

[DK44]

ASME Sec VIII Div 1 specifies minimum PWHT temperatures at Tables UCS-56.
1. What are the maximum limits for PWHT?
2. Are maximum limits specified in the Code?

 

[david339933]

For Simplicity, Max temp is the lower transformation temp., unless stated otherwise in Table UCS-56. B31.1 has a table of lower transformation temps.(129.3.1)

 

[DK44]

David, Thank you for the reference.
1. How much minimum difference is recommended between PWHT temperature and Lower critical temperature.
2. Is tempering temperature also to be less than lower critical temperature. Then what is the temperature difference
3. I understand that the descending order is
* Lower critical temperature
* Tempering Temperature
* PWHT Temperature.
But what minimum differences are to be maintained.

 

Higher temperature costs, and in the great majority of applications there is no technical need to go very much higher than the minimum holding temperature. Is there some unusual demand prompting this enquiry?

"Everyone is entitled to their own opinions, but they are not entitled to their own facts."

 

[DK44]

Thanks ironic.
Kindly advise on recommended minimum temperature differences at the scenario 3.

 

[david339933]

I have not responded for undoubtedly the same reason others have not chimed in.....this information can be found via a quick google search.

 

[DK44]

Thank you david.
If you come across any web info pl give me the link.

 

I think David meant that you do the search.

"Everyone is entitled to their own opinions, but they are not entitled to their own facts."

 

[r6155]

See PD 5500: the PWHT temperature shall be at least 30 °C below the maximum tempering temperature.
In table 4.4-1 is clearly defined PWHT temperature limits for material groups, i.e. 550ºC -600ºC

Regards
r6155

 

[DK44]

Thank you r6155.
1. I observe that
as per EN 13445 10.5.3, "generally maximum actual PWHT temperature
shall be at least 30°C below the minimum actual tempering temperature ...."

Where as as per PD 5500, 4.4.6.3, "the PWHT temperature shall be at
least 30 °C below the maximum tempering temperature,..."

There appears difference in the above codes and former one appears logical. Please correct me if I am wrong.

2. What about difference between Lower critical temperature and Tempering temperature. How much minimum difference is recommended.