Holding Time PWHT of Carbon Steel Vessel

For such a thin plate PWHT is necessary?

Why customer is not accepting? have you not taken approval beforehand?

The WPS approval automatically takes care of this aspect. The temperature gradient of 150⁰C/Hr is a bit too high. This must be the cause of non-acceptance.

There are so many reasons why an owner might not accept the PWHT. Are you the manufacturer performing your own stress relief, or are you a specialty company? If you're the manufacturer, what stamp do you posess? What section of the code was this designed to? Did you get your PWHT parameters from the same section? Was PWHT performed in accordance with the requirements? Were recorders used, does the data collected correspond to requirement, were there suffiecient monitoring points...etc. You said the soak time was 75 Mts. that feels insuficient, and what was the soak temp.

These are the things the owners Quality Assurance program looks at carefully to satisfy their insurer.

We all want what we pay for.

Thank you for your reply

Code of Construction is ASME Sec VIII Div 1 UCS 56 Pwht cycle we have the seperate furnace and we done the same furnace. Soak Temp. 610 Deg. and time 75Mts. But we know as per code 1hour/ Inch and 15 Minutes Min. Already we done higher than the code. AfterPWHT Hardness test carrried out and found Less than 175 BHN.and weld and HAZ and Parrent material (Reqd.200BHN Max.)

has the procedure qualification done? Since the holding time is excessive, the customer might have some doubts abot reduction in notch toughness.

What we don't know is: 1. Did the buyer specify a more restrictive PWHT method? Note that the buyer or his engineer may specify requirements more restrictive than the Code. 2. Did your AI approve A) the WPS & PQR? B) the PWHT results? 3. What aspects of the PWHT did the buyer not accept? 4. Was there any NDE required after PWHT?

With this thickness of CS, PWHT would be required for service?

How many thermocouples did you use?

Did you have an approved PWHT procedure?

Did any thermocouples fail to reach temperature?

Did any thermocouples exceed the maximum temperature?

Was the calibration for the recorder up to date?

Was there flame impingement on the vessel?

hy not ask your client?

Was all welding complete?

Refer to the CR4 Thread PWHT Holding Time, and download the following file which demonstrates an example for how to construct the curve for PWHT as per ASME code, Section VIII, Div. 1: PWHT-Example.