American Welding Society Forum
Hello, I was searching in the code but I couldn´t find a table or and written description for the preheating temperature vs thickness. In QW-406 is about preheat but does not show someting like a table. Where I find preheat temperature vs Thickness in ASME?
Try Appendix R of ASME VIII Div 1
By Jovi Zhu
Section IX is about welding procedure and performance qualification. Preheating is a variables as required by Section IX to be qualified by the manufacture himself.
In other word, Section IX doesn't give you preheat temperature for your specific application but rules of how to qualify.
Section IX is not a CONSTRUCTION section. Take a look at the construction section governing your product you can find mandatory or recommended preheat temperature.
Non-mandatory appendix A-100 of Section I;
Non-mandatory appendix R of Section VIII;
Para. 131 of B31.1;
Para. 2.5.1 of NBIC Part 3
Note that all Code give minimum preheating requirement. From engineering judgement you may need to consider more than Code mimimum requirement.
As most Codes state:
"The need for and the temperature of preheat are dependent on a number of factors such as chemical analysis, degree of restraint of the items being joined, material thickness, and mechanical properties. The welding procedure specification for the material being welded shall specify the preheat temperature requirements."
That is to say, "you are on your own"~ LOL~
To establish a preheat temperature, in addition to meet MINIMUM Code requirement, you can refer to some pubilcation of material mill such as V&M for a specific material or handbook/guideline from a filler metal manufacturer such as Esab/Metrode for a specific filler metal. Also to some industry practice such as technical reports by EPRI......
degree of restraint is up to your product, so, again, you are on your own.
(Take a look at Annex I (Normative) Guideline on Alternative Methods for Determining Preheat of AWS D1.1-2010, you will know how much you need to consider to establish preheat temperature.)
Hope the above would be of help.
You have clear a lot everything!!! thank you very very much for your help.
ASME IX is always used with ASME Constructing Codes and *sometimes* is used with other Codes or other Standards.
Almost every ASME Constructing Code gives guidance or requirements for preheating.
You're not on your own, you just need to know where to look.
Yes if your purpose is nothing more than Code compliance and you are just looking for minimum preheat requirement of construction code, then you can always find it on papers. I already addressed some examples of where to find in my previous post.
However, if your purpose is to ensure satisfactory completion of the welded joint, then you need to consider more and that was why I said "you are on your own".
Read following words and you will see.
Foreword of ASME B&PVC:" The Code is not a handbook and cannot replace education, experience, and the use of engineering judgment."
ASME B&PVC Section I, Rules for Construction of Power Boilers
PW-38.1 The need for and the temperature of preheat are dependent upon a number of factors such as chemical analysis, degree of restraint of the parts being joined, elevated temperature mechanical properties, and material thicknesses. Some practices used for preheating are escribed in A-100 as a general guide for the materials listed by P‐Numbers of Section IX. It is cautioned that the preheating suggested in A-100 does not necessarily ensure satisfactory completion of the welded joint and that the requirements for individual materials within the P‐Number listing may have preheating more or less restrictive than this general guide. The welding procedure specification for the material being welded shall specify the minimum preheating requirements described in the welding procedure qualification requirements of Section IX."
Please allow me to understand your statement.
1. Yes if your purpose is nothing more than Code compliance and you are just looking for minimum preheat requirement of construction code,
2. However, if your purpose is to ensure satisfactory completion of the welded joint, then you need to consider more and that was why I said "you are on your own".
3. The welding procedure specification for the material being welded shall specify the minimum preheating requirements described in the welding procedure qualification requirements of Section IX."
Can you give example on the above item 2, which normally reflected to your WPS?
That is to say, "you are on your own"~ LOL~
Preheating Prior to Welding
Let me share some examples.
Suppose that you are working on Section I and your purpose is nothing more than Code compliance. Then you can even ignore A-100 since it is non-mandatory. As per PW-39 you may preheat just 300F for some Gr.22 (P5A) material and qualify your WPS by some small pieces of test coupons without the actual restraint of the actual product joints. And your AI would not say no to you since you are of Code compliance.
However, if you look at filler metal handbook by Metrode, you will see "Preheat and interpass temperature 250°C (480F) minimum, up to 300°C (570F) for thick sections" for Gr.22 filler metal of various processes.
Another example I can remember for now is about the dissimilar metal welds (DMW's) in power generation industry.
A new filler metal called EPRI P87 is now commercially available and if you have read the EPRI Technical Report #1019786 you will see a minimum of 350F preheat temperature was applied for a successful qualification test for T22-TP347.
And again, if your purpose is nothing more than Code compliance, you just need to apply 300F and you may have problem with the guide bend test since this the filler metal developed to join stainless steel and low alloy steel has a chemical composition "in between" (you can compare it with Gr.91).
Whenever you have quality problems and your client is questioning, you can never defend by explaining that "I have meet all the Code requirement". From this point, I would like to say again :"You are on your own". ASME B&PVC Committee will not pay the back charge to your client for you.
Very correct or should I say Bon Jovi!
You back on deck ?
Shane did u get it? Jovi/ Bon Jovi? Ha! Only a joke! What he writes is pretty good. I need some help to get instant posting on UK Welding Forum, I have spoken to Rodofgod and he wants me back and I am sure other sensible people do.This AWS Forum is really free world as they have the right people in place to moderate it but the UK Forum is so restrictive of free speech due to ignorance or should put it more politely the moderators lack of welding knowledge or understanding of what is free speech. This is the greatest thing (in my opinion) that Americans have and that is (free speech).
Most people who input on the AWS Welding Forum are CWI's and post technical questions on code requirements whereas the UK Welding Forum is predominantly posted by hands on welders. It is very different, maybe because the Americans developed "Quality, Deeming etc".
People who input generally do require help I think, why they do not inquire within their company I do not know but they do need help.
AWS Forum have a number of really good guys who answer questions (albeit, in my opinion with too much verbage!)
The UK Welding Forum is in dire need of direction. They really need to avoid the "job section" and concentrate about what welding is about, technical issues. I cannot post direct so if you want me to help others then let me know.
Bon Jovi is my favorite band.
....too much verbage!
like long-winded? i would prefer direct answer to the questions
Ask for the Cliff Notes sectgion.
You get what you pay for in here Bert and the last time I checked, It's all free!!!
You don't want too much wind??? Then empty you pockets and pay up!
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