PWHT required after Preheat for CS or LTCS

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thanh tung Nguyen

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Dec 16, 2020, 10:47:11 PM12/16/20
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Dear Experts,

Hope you all are well.

I have a question is about the weld of the base material of CS (or Low temp. CS) with wall thickness greater than 25mm, Do we still required PWHT if we applied a preheating process before, or PWHT is no longer mandatory?

And which reference can be found?

Thank you & best regards./.

Jamie Reyes

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Dec 16, 2020, 10:55:13 PM12/16/20
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What is the code of construction?
What is the type of service?
Is Lethal Services involved?
Need the above mentioned information.....

Regards,
Jamie Reyes
J.R. Machine Company, Inc.


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furkan topaloğlu

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Dec 17, 2020, 12:03:09 AM12/17/20
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In order to reduce the risk of cold cracks due to thickness and stress, PWHT can be applied to provide slow cooling after welding.

Jamie Reyes <jamiejrm...@gmail.com>, 17 Ara 2020 Per, 06:55 tarihinde şunu yazdı:


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Regards / Saygılarımla

 

Furkan TOPALOĞLU

Metallurgy and Material & Welding Engineer

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Kannayeram Gnanapandithan

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Dec 17, 2020, 3:07:57 AM12/17/20
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if code of construction is ASME sec1, it is required or if it is Sec8, preheat is enough upto 38mm

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thanh tung Nguyen

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Dec 17, 2020, 3:07:57 AM12/17/20
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Dear Mr. Jamie,

ASME B31.3 is applied.
Service for Ammonia Liquid Design Temp from -35 to 70 degree C. I am not sure about whether lethal but it's a dangerous service.

Thank you for your help.

Best regards

Vào Th 5, 17 thg 12, 2020 vào lúc 11:55 Jamie Reyes <jamiejrm...@gmail.com> đã viết:

Jamie Reyes

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Dec 17, 2020, 3:39:33 AM12/17/20
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 Based off the information that you have given, Post weld heat treatment is not mandatory if preheat of 200°F was applied to the welded joint, with the welded joint being greater than or equal to 1 inch in thickness. 
Cheers.....

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Ramin Kondori

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Dec 18, 2020, 11:39:57 PM12/18/20
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Dear Thanh,

Aside from code requirements, it depends on toughness requirements for the job (Impact test).
The welding procedure qualification for LTCS materials (e.g. A333) normally includes impact testing (e.g. at -48C); and without PWHT, it is not easy to pass this test and in the end, you have to perform PWHT to have your PQR approved. Most probably, you have to perform PWHT on all thicknesses. 

Regards  
Ramin  Kondori
Sr. QA/QC & Welding Engineer
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PG-Dip. in Welding Engineering (IWE  AT  0070)
BSc. in Civil Engineering (IUT)
BGAS Painting Inspector
ASNT Level I&II
                        
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José Juan Jiménez Alejandro

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Dec 20, 2020, 10:22:48 PM12/20/20
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I think it is extremely important that colleagues who ask a question in this forum structure it in the most complete way possible, because those of us who are here in the forum cannot be guessing many of the variables of the problem posed, many assume that some issues are taken for granted, but the truth is that we are not facing the problem you are presenting and therefore we cannot measure the magnitude of this problem, hence the importance of asking exact questions, giving all possible details, these They are: Exact material specifications, building code if any, customer specifications, type of service and a thousand other things that will serve us and will shed light on the nature of the problem and this will give us more data to help them in the most efficient way. possible, you see the problem live, we will have a more or less clear idea as you provide the largest and best amount of information ion, WE DON'T GUESS FOR MANY YEARS THAT WE HAVE EXPERIENCE.
Thanks for understanding.
Cheers!.



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Skype: jjjimeneza





Jamie Reyes

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Dec 21, 2020, 12:30:39 AM12/21/20
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Mr. Jose Juan Jimenez,
 I agree wholeheartedly, but you need to remember also that the people that are asking these questions are not in tuned with every aspect that is needed.  Now that you brought it to their attention, I’m sure they will understand now, and like I stated previously, I agree with everything you stated. It frustrates me a lot, but I always take a step back and remember what I just mentioned above. Out of all the forms that I belong to, I would have to say that this is the least structured but nonetheless, I am here to help where ever and whenever need be. Keep educating, and stay blessed......

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