For Post heating after completion of welding (There should not be interruption during welding) with out cooling to room temperature i.e. from preheating temp. you require to heat the joint uniformly to 350-400C (Through heating) Soak for min 2hrs min (Soaking time depends upon Joint Thk) and after post heating let it cool in normal way but not fast cooling.
However you have to monitor temperature properly all over the joint during heating ./soaking .
This process is called DHT (Dehydogenation treatment ) This is to take care of Hydrogen Induced Cracking Generally require for P5 ,P4 material with higher thickness and Restrain joint
Handling of P5A (CrMo V ) steel is very critical require lot of discipline right from Cutting , Edge preparation, Consumable handling , Preheating , Interpass temp. Post heating , Weld joint welding of LS, CS, Shell to Nozzle joint,
Little negligence will cause cracks in weld and HAZ
Regards
Hegde p.B.
From: materials-welding@googlegroups.com [mailto:materials-welding@googlegroups.com] On Behalf Of kiran chavda
Sent: Wednesday, December 09, 2009 3:48 PM
To: materials-welding@googlegroups.com
Subject: Re: [MW:3811] Welding of P5A & P5B Material
| Thank for your quick replay, Yes, it is there in ASME B31.1, as per 131.4.5- Preheating & as per Table 132- Post weld heat treatment. But my question is related to post heating, means after complication of welding, immediately we have to do post heating for 2 hours @ 250˚C or 2.5 hors @ 200˚C ……( it is not a PWHT) Please give me some information for this P5A & P5B material, because we have to establish new procedure for those materials…… Regards K.C.Chavda
--- On Wed, 12/9/09, Devarajan Ramasamy <neo.devarajan@gmail.com> wrote:
From: Devarajan Ramasamy <neo.devarajan@gmail.com>
Subject: Re: [MW:3810] Welding of P5A & P5B Material
To: materials-welding@googlegroups.com
Date: Wednesday, December 9, 2009, 2:45 PM
Refer to ASME B31.1 page 83 and 84 for preheating and post heating requirement for P5A and P5B. Generally, the minimum thickness for preheating & post heating for P5A material is above 13mm and for P5B material is above 10mm. Heating temperature for P5B material is 740 ~ 780 deg C and for P5A material is 680 ~ 720 deg C. Heating time varies with the thickness of the material. P5B material & P5A material requires argon backing.
For the welding of SA 335 Gr. P91 (PNo-5B, Group No-2) Material………
1) What is the Preheating Temperature?
2) What is the Post heating Temperature & Time ?
3) PWHT is require or not ?
4) While welding (GTAW) Backing is require if yes, then Argon is OK ?
For the welding of SA 335 Gr. P22 (PNo-5A, Group No-1) Material………
1) What is the Preheating Temperature?
2) What is the Post heating Temperature & Time ?
3) PWHT is require or not ?
4) While welding (GTAW) Backing is require if yes, then Argon is OK ? On Wed, Dec 9, 2009 at 3:43 PM, KC <kc.chavda07@gmail.com> wrote: Can any body inform about the …..
For the welding of SA 335 Gr. P91 (PNo-5B, Group No-2) Material………
1) What is the Preheating Temperature?
2) What is the Post heating Temperature & Time ?
3) PWHT is require or not ?
4) While welding (GTAW) Backing is require if yes, then Argon is OK ?
For the welding of SA 335 Gr. P22 (PNo-5A, Group No-1) Material………
1) What is the Preheating Temperature?
2) What is the Post heating Temperature & Time ?
3) PWHT is require or not ?
4) While welding (GTAW) Backing is require if yes, then Argon is OK ?
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Regards,
~ DEVARAJAN RAMASAMY~
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