Induction Heating for PWHT

'....because will it affect the microstructure of pipe mtl or not?...'

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It depends on the temperature and duration in each part of the sequence.

Generally, yes, there will be an affect on the microstructure if the temperature is raised to a sufficient point.

our procedure is raise the temp from ambient to 400deg cel and from 400 to 720 as 200/hr and maintain 720 for 1 1/2hrs and cooldown from 720 to 400 as 200/hr. so totally 5hrs.

Well, if that's the procedure to be followed, then shortening the time, by whatever method of heating, counts as a change to the procedure regardless of the crystallography. The original question is now unanswerable.

I am by no means an expert but I do remember that the rate of temperature rise and the length of the temperature soak affect the type of micro sturcture that develops. A change in the temperature rise or a change in the soak time will affect this structure and needs to be carefully reviewed with people more knowledgable than me. And with the customers design team. They had some reason to specify the PWHT that you are trying to change.

sure there will be effect on the micro-structure of pipe but its been used in PWHT for oilfield pipeline .

they are using half circle heating coils to cover the pipe .it will take lesser then the half time then resistance heaters can be more faster (depend on your induction system )more kilowatt ,less the heating time.

kindly give me your personal e mail to send you system drawings (how it works)

thanks sohail..

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we are oil and gas products manufac company only.

There must be a reason that "we need to follow a particular procedure and it takes 5hrs to complete." Perhaps you are unaware of the reason the procedure was written the way it was.

You cannot alter the process without authorization from the process engineer or controlling entity.

for resistance heating we are following the procedure i mentioned before. but i heard the proce for induc method is totally different and we can reduce the time so much. no need to follow the existing proce, we can generate a new procedure.

Then the correct thing to do is to run and qualify the new procedure according to the results obtained, rather than wasting time on CR4.

You must abide by the specification regarding time to raise temperature, hold time , and cooling rate. Anything outside the specified procedure is NOT acceptable. If you are not aware of the rules, you should not be in your position!!

I know that... i need to follow my procedure and following. my question is, once we use induc can we reduce time r not?. because i heard the procedure for induc and resis are different. i think you dont know that.

I think you are not aware of this rules.........................................

If you know that you have to follow the set down procedure, as stipulated by ASME or whatever code, then follow the procedure and stop asking foolish questions. Surely you have some qualificationss and experience. If not get someone to do the job

I have enough qualification and experience, i know there is std for induc heating in ASME. but i am not very sure abt the spec number. i mentioned this matter in previous msg again you are asking foolishly.

I know there are good experienced people in CR4(NOT like you just discouraging people even dont know anything).

If u r well exp in this, i will give u job, and good pay to do this...

There is none so deaf as the individual that will not listen...

13 chrome schedule 80 pipe is a super martensitic stainless steel that has been extensively studied. Please see (publications.npl.co.uk/npl_web/pdf/matc108.pdf) for an excellent review of work done. Yes, it is normally heat treated after welding (PWHT) and the required heat treat parameters will depend on the service requirements of the pipe.