During welding (especially in SMAW Process) of low alloy steel, there is more possibility of hydrogen entrapment
Which leads to severe defects.
To avoid such kind of defects dehydrogenation treatment i.e. after completion of welding before reaching the preheat
Temperature, the weld shall be heated to 320 – 350 deg Celsius for 2 hrs and the same shall be cooled slowly by closing any insulation after
Post heat treatment.
Note: The time 2 hrs is considered only after the weld metal temp. reaches 320 deg Celsius.
From: materials-welding@googlegroups.com [mailto:materials-welding@googlegroups.com] On Behalf Of kiran chavda
Sent: Wednesday, December 09, 2009 1:18 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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The views expressed/exchnaged in this group are members personel views and meant for educational purposes only, Users must take their own decisions w.r.t. applicable code/standard/contract documents.
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