[MW:8654] MW:8637- tempering of plates

Asad,

 

The plates are supplied with normalizing and tempering heat treatments, which is done in the mills with a great control. Since the head will be hot formed , forming temperature is typically > AC1 temperature (typically over 920 deg C for LAS), the effect of Mill-tempering would be lost.

 

Hence following hot forming the dished head has to be re-tempered (preferably at the tempering temperature used in the Mill).

 

How much is the variance in tempering temperature performed in the mill,i.e required as per code vs done at the mill(as indicated below). If the variance is minor, re-heat treatment of the plates would not be desirable. However tempering following forming (as mentioned above) would be needed.

 

To be on the  safe side and be assured of the plate quality, you may please ask for simulation test coupons (with multiple heat treatments as above) from the mill.

 

Thanks.

Pradip Goswami,P.Eng,IWE.

Welding & Metallurgical Specialist & Consultant

Email-pgoswami@sympatico.ca,

pgoswami@quickclic.net

 

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From: asad azmi <azmiasadayub@gmail.com>
To: materials-welding@googlegroups.com
Sent: Wed, 8 December, 2010 6:47:01 PM
Subject: [MW:8604] tempering of plates

Dear All,

 

Greetings.

 

A vessel is to be fabricated as per ASME SEC VIII DIV 1 for data as below- use  

 

Plate Material  -  SA 387 GR 12 CL2  ,   80 THK.

 

Plate is to be used for dished head. as per the  ASME SEC IIA  normalizing and tempering is required for the plate.

 

forming of Dished head will be  by hot forming.

 

during reveiw of MTC it was observed that Tempering temeprature was not meeting the requirement.therefore re - tempering is required for the plate.

 

My question is whether re - tempering is required for the plate OR it can be done after Hot Forming of dished head.

 

As per the requirment after hot forming, dished head will under go Normalizing and tempering.

 

Pls suggest.

 

Thanks in advance for your valuable suggestions.

 

Regards

 

Asad Azmi

 

 

 

 

 

 

 

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